University Track Graduate Writing
Research Proposal Assignment
For this assignment, you will create a 2-3 page research proposal on a topic related to your future
major/area of study that is of interest to you. In this proposal, you will be expected to discuss the
specific area of research you will be conducting for your future assignments in this class (annotated
bibliography and final paper). You cannot write your paper on a topic that has not been approved, so
this research proposal will allow you to discuss your topic in detail with your teacher, and this will also
help inform your stance on the topic.
Research proposals are a common aspect of graduate classes (and academic careers, if you choose to
continue in this area). This research proposal follows a very basic format that is shorter and much
simpler than research proposals you may have to do in the future, but this will allow you to get a good
start on the process now.
Please format this proposal using 12-point Times New Roman, double-spaced, with 1-inch margins. This
assignment will be due in the D2L Assignments folder before class on Monday, July 9.
Research Proposal Template
I.
II.
III.
IV.
Proposed research topic
a. Background on the topic
b. Current controversies or academic debates/differing viewpoints related to the topic
c. Why it interests you and is appropriate to your field of study
Research questions
a. Two to four research questions based on your current understanding of the topic; this
will inform your selection of articles
b. Questions should be focused, specific, and attainable (you should be able to find the
answers, or at least come close, through completing this assignment)
Research strategy
a. What assumptions do I have about this topic that are informing my stance and research
framework?
b. Where will you find your sources?
c. How will you determine which sources are appropriate?
d. How will you evaluate your sources once you find them?
Sources
a. What sources do you already have that are informing your opinion? (Aim to have at
least three for the proposal (you will need 5-7 for the final paper)
Example Research Proposal
1. Proposed research topic: Architecture and water conservation
a. Water conservation is a major issue in dry areas such as Tucson, and much of the water
that falls on this area is not collected appropriately. Within the new focus on sustainable
architecture, there have been advances in the building of homes and office buildings that
now collect rainwater more efficiently, leading to better water conservation (Campana et
al, 2017). In recent years, this type of architecture has moved from the fringe to the
mainstream, with modern office buildings now often being designed to not only save
energy but also to collect rainwater, which may be used for gardens, landscaping, or
industrial uses (Campisano et al, 2017; Xu, Xiao, & Wei, 2016).
b. The main controversies related to this topic surround not whether architecture should
strive to be more sustainable, but how architects can work sustainable plans into their
designs in a cost-effective way that will make sustainable architecture more attainable for
everyone, including people who are building homes or offices on a tight budget. The
considerations must include cost, efficiency, and sanitation.
c. This topic is very interesting to me because I care about protecting the environment, and
as an architect, I would like to incorporate this concern into my designs for my future
work. Sustainable architecture is becoming more and more popular in my field around the
world, and having a good understanding of ways to be sustainable in my designs will help
me adapt to potential client concerns as well as follow my dreams of protecting the
environment in a larger way.
2. Research questions
a. What forms of passive water collection (use of berms, swales, and other landscaping
features) are most effective and efficient in the environment of Southern Arizona?
b. What forms of active water collection (use of cisterns, etc.) are most effective for small to
medium homes in the environment of Southern Arizona, and how can these water
collection methods be incorporated into initial home design?
3. Research strategy
a. Assumptions: My initial assumption about this topic is regarding the fact that water
conservation is: 1) a possible and beneficial aspect of architecture; and 2) that potential
clients will be interested in learning more about how they can incorporate sustainable
facets such as passive and active water collection methods into their small to medium
homes or offices.
b. Sources: I plan to find most of my sources in online academic journals related to
architecture and sustainability, which are available through the University of Arizona
library website. I may also use one or two popular sources, such as articles from
reputable newspapers or magazines, to provide a popular insight into the topic.
c. For the academic articles, I will need to ensure that the articles address the research
questions I have listed above. If the articles do not address these questions directly, I will
only use them if they address some aspect of these questions that is immediately relevant
to my research topic. I will also need to evaluate each of these sources and provide
critiques of them, including critiques of their methodology, theoretical framework, or
basic assumptions. If I use any popular sources, I will need to check the reputation of the
sources and understand any bias that may be present in their writing.
4. Sources
Campana, P. E., Quan, S. J., Robbio, F. I., Lundblad, A., Zhang, Y., Ma, T., & ... Yan, J. (2017).
Optimization of a residential district with special consideration on energy and water
reliability. Applied Energy, 194751-764. doi:10.1016/j.apenergy.2016.10.005
Campisano, A., Butler, D., Ward, S., Burns, M. J., Friedler, E., DeBusk, K., & ... Han, M. (2017). Urban
rainwater harvesting systems: Research, implementation and future perspectives. Water
Research, 115195-209. doi:10.1016/j.watres.2017.02.056
Xu, J., Xiao, D., & Wei, C. (2016). Architecture Water-saving Design and Building Technique of Sponge
Yard. Journal Of Landscape Research, 8(6), 16-19. doi:10.16785/jissn1943-989x.2016.6.005
Nutrition, Metabolism & Cardiovascular Diseases (2013) 23, 122e129
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/nmcd
Impact of overweight and obesity on cardiac benefit
of antihypertensive treatment
E. Gerdts a,*, G. de Simone b, B.P. Lund a, P.M. Okin c, K. Wachtell d,
K. Boman e, M.S. Nieminen f, B. Dahlöf g, R.B. Devereux c
a
Institute of Medicine, University of Bergen, and Department of Heart Disease, Haukeland University Hospital, N-5021,
Bergen, Norway
b
Department of Clinical and Experimental Medicine, Federico II University Hospital, Naples, Italy
c
Division of Cardiology, Weill Medical College of Cornell University, NY, USA
d
Department of Cardiology, Gentofte University Hospital, Copenhagen, Denmark
e
Department of Medicine Skeleftaa Hospital, University of Umeaa Skelleftaa, Sweden
f
Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland
g
Department of Medicine, Sahlgrenska University Hospital e Östra Gothenburg, Sweden
Received 9 November 2010; received in revised form 6 February 2011; accepted 29 March 2011
Available online 19 July 2011
KEYWORDS
Body mass index;
Obesity;
Left ventricular
hypertrophy
Abstract Background and aims: Increased body mass index (BMI) has been associated with
increased cardiovascular morbidity and mortality in hypertension. Less is known about the
impact of BMI on improvement in left ventricular (LV) structure and function during antihypertensive treatment.
Methods and results: Annual BMI, echocardiograms and cardiovascular events were recorded in
875 hypertensive patients with LV hypertrophy during 4.8 years randomized treatment in the
Losartan Intervention For Endpoint reduction in hypertension (LIFE) echocardiography substudy. Patients were grouped by baseline BMI into normal (n Z 282), overweight (n Z 405), obese
(n Z 150) and severely obese groups (n Z 38) (BMI 24.9, 25.0e29.9, 30.0e34.9, and
35.0 kg/m2, respectively). At study end, residual LV hypertrophy was present in 54% of obese
and 79% of severely obese patients compared to 31% of normal weight patients (both p < 0.01).
In regression analyses, adjusting for initial LV mass/height2.7, higher BMI predicted less LV
hypertrophy reduction and more reduction in LV ejection fraction (both p < 0.05), independent of blood pressure reduction, diabetes and in-study weight change. During follow-up, 91
patients suffered cardiovascular death, myocardial infarction or stroke. In Cox regression analysis 1 kg/m2 higher baseline BMI predicted a 5% higher rate of cardiovascular events and 10%
higher cardiovascular mortality over 4.8 years (both p < 0.05).
* Corresponding author. Tel.: þ47 55972170; fax: þ47 55975150.
E-mail address: eva.gerdts@med.uib.no (E. Gerdts).
0939-4753/$ - see front matter ª 2011 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.numecd.2011.03.008
Cardiac benefit of BP reduction in obesity
123
Conclusions: In hypertensive patients in the LIFE study, increased BMI was associated with less
reduction of LV hypertrophy and less improvement in LV systolic function which may contribute
to the observed higher cardiovascular event rate of treated hypertensive patients.
ª 2011 Elsevier B.V. All rights reserved.
Introduction
The increased prevalence of hypertension and diabetes in
obese subjects has been suggested to at least partly explain
the increased cardiovascular risk observed in obesity [1,2].
In hypertensive populations obesity has been associated
with higher prevalence of left ventricular (LV) hypertrophy
as well as lower LV systolic function [3e5]. It is well known
that systematic antihypertensive treatment induces
regression of hypertensive LV hypertrophy [6]. However, as
documented from the Losartan Intervention For Endpoint
reduction in hypertension (LIFE) study that randomized
9193 hypertensive patients with signs of LV hypertrophy on
the electrocardiogram to 4.8 years blinded losartan- or
atenolol-based antihypertensive treatment, concomitant
obesity predicted increased cardiovascular mortality during
follow-up independent of other individual cardiovascular
risk factors and type of antihypertensive treatment [7].
Furthermore, clustering of metabolic abnormalities has
been associated with blunted reduction in hypertensive LV
hypertrophy assessed by electrocardiography [8].
Less is known about the impact of obesity on cardiac
benefit, including regression of LV hypertrophy and
improvement of LV systolic function measured by serial
echocardiograms during systematic long-term antihypertensive treatment. Thus, the aim of the present analysis
was to assess whether obesity itself attenuates the known
beneficial effects of aggressive antihypertensive treatment
on LV structure and systolic function.
echocardiogram before a primary study endpoint and thus
were eligible for the present analysis. From these, 2
patients were excluded who did not have body mass index
(BMI) measured at baseline. The study population was
grouped by baseline BMI into underweight (n Z 4, BMI
3.5 and 35 mg/mmol, respectively [14]. All patients gave informed consent to participate in the LIFE echocardiography substudy, which was
approved by regional ethics committees in all participating
countries.
Methods
Echocardiography
Patient population
The present analysis was added to the LIFE echocardiography analysis plan before unblinding of data. The LIFE
echocardiography study, a prospectively planned substudy
of the main LIFE study, enrolled 960 of the 9193 participants in the parent trial for annual echocardiographic
follow-up [9]. Results from the main LIFE study that
randomized patients aged 55e80 years with essential
hypertension
(baseline
blood
pressure
160e200/
95e115 mm Hg) and electrocardiographic (ECG) LV hypertrophy (according to Cornell voltage-duration or SokolowLyon voltage criteria) from Norway, Sweden, Denmark,
Finland, Iceland, the United Kingdom and the United States
of America to a mean of 4.8 years double-blind treatment
with losartan compared to atenolol demonstrated the
superiority of losartan-based treatment in reduction of
cardiovascular events and signs of LV hypertrophy on ECG
[10,11]. Of the 960 patients enrolled in the LIFE echocardiographic substudy, 881 patients had LV dimensions
measured at enrollment and on at least one follow-up
Organization, patient recruitment, protocol, and echocardiographic methods used in the LIFE echocardiographic
substudy have been previously published [9,15]. All
echocardiograms were sent to the Cornell Echocardiography Reading Center for blinded interpretation.
Measurements of LV diameter and wall thicknesses were
made on two-dimensional parasternal long-axis views
according to American Society of Echocardiography standards and used for calculation of endocardial fractional
shortening, LV ejection fraction by the Teichholz method
and LV mass using an autopsy-validated equation [16]. LV
mass showed excellent inter-study reliability in a separate study of 183 patients from the Reading Center [17].
LV hypertrophy was considered present if LV mass
indexed to height2.7 exceeded 49.2 g/m2.7 in men or
46.7 g/m2.7 in women [18]. Diastolic relative wall thickness was calculated as posterior wall thickness/internal
radius and considered increased if 0.43 [19]. Individual
LV geometry was assessed from LV mass/height2.7 and
relative wall thickness in combination and patients
124
E. Gerdts et al.
grouped in the 4 following LV geometric patterns: In
patients without LV hypertrophy, LV geometry was
considered normal if relative wall thickness also was
normal and characterized as concentric remodeling if
relative wall thickness was increased. In patients with
increased LV mass, hypertrophy was classified as eccentric or concentric based on the presence of normal
or increased relative wall thickness, respectively [20].
Midwall shortening and its relation to circumferential
end-systolic stress at the level of the LV minor axis
(stress-corrected midwall shortening) were calculated
using a previously validated formula [21,22]. Mitral and
aortic regurgitation were assessed by color Doppler using
a previously described 4-category grading system [23,24].
Supine blood pressure measured by arm cuff sphygmomanometer at the end of the echocardiogram was used in
calculation of hemodynamic variables. Heart rate was
measured from the echocardiographic recordings.
Endpoints
The primary composite endpoint in the LIFE trial included
cardiovascular death and fatal and nonfatal myocardial
infarction and stroke. The components of the primary
endpoint were also prespecified secondary endpoints. All
endpoints were validated by an independent endpoint
classification committee [11].
Statistical analyses
Data management and analysis were performed using SPSS
17.0 (SPSS, Chicago, IL) software. Data are presented as
Table 1
mean (standard deviation) for continuous variables and as
percentages for categorical variables. Between-BMI class
comparisons were made by ANOVA with Scheffe’s post-hoc
test or chi-square statistics, as appropriate. LV dimensions, mass and systolic functional variables were compared
between BMI classes using a general linear model including
gender and African American ethnicity as covariates. Intreatment changes in variables were taken as the difference between the value at baseline visit and the value at
the final study visit or the last study visit before occurrence
of a primary composite endpoint and calculated in each
individual patient. Impact of obesity on in-treatment
reduction in LV mass/height2.7 was assessed by multiple
linear regression analysis using an enter procedure with
colinearity diagnostics controlling for baseline LV mass/
height2.7, age, gender, race, smoking, history of myocardial
infarction, in-treatment systolic blood pressure and albuminuria and randomized study treatment. A similar model
was used for assessing the impact of obesity on intreatment improvement in LV systolic function (LV ejection fraction, midwall shortening and stress-corrected
midwall shortening) adding in-treatment reduction in LV
mass/height2.7 to the covariates. In subsequent models an
indicator variable for prevalent and incident diabetes
mellitus and in-treatment change in body weight as
a continuous variable were added as covariates.
The associations of baseline BMI with the primary
composite endpoint and with cardiovascular death,
myocardial infarction, and stroke as separate endpoints
were evaluated in Cox regression models including systolic
blood pressure and LV mass as time-varying covariates,
updated at each annual visit, and baseline Framingham risk
Baseline characteristics in normal, overweight, obese and severely obese groups of patients.
Variable
Baseline
Age (years)
Women (%)
Diabetes (%)
AfricaneAmerican (%)
Weight (kg)
Body mass index (kg/m2)
Systolic BP (mmHg)
Diastolic BP (mmHg)
Mean BP (mmHg)
Pulse pressure (mmHg)
Heart rate (bpm)
Albuminuria (%)
Last study visit
Weight (kg)
Body mass index (kg/m2)
Systolic BP (mmHg)
Diastolic BP (mmHg)
Mean BP (mmHg)
Pulse pressure (mmHg)
Heart rate (bpm)
Albuminuria (%)
New-onset diabetes (%)
Normal weight (n Z 282)
Overweight (n Z 405)
Obese (n Z 150)
Severely obese (n Z 38)
67 7
40
6
11
67.0 8.5
23.0 1.5
174 14
97 9
123 8
77 16
71 11
26
66 7
34*
11*
10
79.0 9.0**
27.3 1.4
173 14
99 8**
124 8
73 15**
72 12
26
65 6*
55*
15*
15
89.7 11.0**
31.9 1.5
175 14
99 9
124 8
76 15
73 11
30
62 6**
71*
21*
45*
105.3 16.9**
39.4 4.9
174 15
97 9
123 8
76 17
71 8
50
68.2 10.5
23.6 2.8
146 17
80 9
102 10
65 16
67 12
23
3
80.3 10.6**
27.6 2.4**
144 16
83 10*
104 10
61 15*
67 11
23
6**
89.6 12.0**
31.7 3.0**
145 16
83 9**
104 10
62 15
70 12
25
9*
104.9 20.0**
38.8 5.0**
143 16
80 11
101 10
62 16
63 10
32
11*
Abbreviations: LV Z left ventricular; BP Z blood pressure.
*p < 0.05; **p < 0.01 vs normal weight group.
Cardiac benefit of BP reduction in obesity
125
Table 2 Baseline LV dimensions, wall thicknesses and systolic function in normal weight, overweight, obese and severely
obese groups of patients.
Variable
Baseline
LV diastolic diameter (cm)
LV systolic diameter (cm)
Septal thickness (cm)
Posterior wall thickness (cm)
Relative wall thickness
LV ejection fraction (%)
Midwall shortening (%)
Stress-corrected midwall shortening (%)
LV mass/height2.7 (g/m2.7)
LV hypertrophy (%)
Aortic regurgitation (%)
Mitral regurgitation (%)
Final echocardiogram
LV diastolic diameter (cm)
LV systolic diameter (cm)
Septal thickness (cm)
Posterior wall thickness (cm)
LV ejection fraction (%)
Relative wall thickness
Midwall shortening (%)
Stress-corrected midwall shortening (%)
LV mass/height2.7 (g/m2.7)
LV hypertrophy (%)
Aortic regurgitation (%)
Mitral regurgitation (%)
Normal weight
(n Z 282)
Overweight
(n Z 405)
Obese
(n Z 150)
Severely obese
(n Z 38)
5.18
3.43
1.15
1.06
0.41
62 9
15.5
97.3
52.8
67
18
26
5.31
3.56
1.16
1.07
0.41
61 8
15.5
97.1
55.7
73*
12
23
5.34
3.61
1.16
1.08
0.41
60 8
15.2
95.8
59.3
85*
11
20
5.63
3.86
1.22
1.13
0.41
59 9
15.0
95.6
74.5
97*
11
37
0.54
0.61
0.16
0.13
0.06
2.2
12.9
10.9
5.28 0.54
3.61 0.64
0.98 0.16
0.87 0.12
59 9
0.33 0.05
16.7 2.5
105.5 13.7
44.1 11.8
31
23
46
0.57*
0.61*
0.14
0.12
0.07
2.0
12.6
11.7*
5.47 0.51**
3.75 0.54**
0.99 0.13
0.89 0.11
59 7
0.33 0.06
16.7 2.0
106.3 11.5
46.5 9.3*
41*
17*
38*
0.56*
0.61*
0.16
0.13
0.07
2.1
13.8
11.3**
5.51 0.53**
3.82 0.57**
1.00 0.14
0.89 0.13
58 8
0.33 0.06
16.4 2.3
104.9 13.6
49.5 10.7**
54*
14*
23**
0.67**
0.69**
0.21*
0.16**
0.07
2.1
12.5
20.2**
5.68 0.59**
3.97 0.64**
1.04 0.18*
0.95 0.18**
57 8
0.34 0.07
15.9 2.0
100.9 11.5
60.2 19.7**
79*
8*
45
Abbreviations: LV Z left ventricular.
*p < 0.05; **p < 0.01 vs normal weight group.
70
63
60
54
49
50
41
30
34
30
40
26
23
20
24
18
10
11
9
5
10
3 0
Results
0
Normal
Overweight
Normal
80
Obese
Conc remod
E-LVH
Severely obese
C-LVH
71
68
70
58
49
60
50
44
38
28
40
30
18
8
20
10
1
3
1
3
2
5
3
0
Normal
score (based on age, gender, diabetes, total and high
density lipoprotein, and baseline systolic blood pressure
and electrocardiographic LV hypertrophy) [25], race and
treatment allocation as fixed covariates [26]. Two-tailed
P < 0.05 was considered significant both in univariate and
multivariate analyses.
Overweight
Obese
Severely obese
Figure. 1 The prevalence of eccentric LV hypertrophy was
greater in higher BMI classes at baseline (upper panel) and the
increase in its prevalence across BMI categories became
steeper at final study visit (lower panel) (all p < 0.05).
At baseline, obese patients groups were younger, and
included more women and patients with diabetes and of
African American ethnicity (all p < 0.01), while blood
pressure was comparable between groups (Table 1). Baseline LV dimensions and wall thicknesses increased progressively with increasing BMI class, and prevalence of LV
hypertrophy was significantly higher in overweight and
obese groups than in the normal weight group (Table 2,
Fig. 1).
During antihypertensive treatment, BMI and body weight
on average increased by 0.2 2.4 kg/m2 and 0.6 kg,
respectively, in the total study population, the normal and
overweight groups had slight increases in body weight and
BMI, while the obese and severely obese groups had slight
decreases in weight and BMI during study follow-up (Table
2). In-treatment blood pressure was comparably reduced
126
E. Gerdts et al.
Table 3 Changes in LV geometric patterns in obese (upper panel) and severely obese (lower pane) patients during antihypertensive treatment.
A. Obese patients
(n Z 150)
Baseline LV geometry
Normal
geometry
(n Z 16)
Concentric
remodeling
(n Z 7)
Eccentric LV
hypertrophy
(n Z 82)
Concentric LV
hypertrophy (Z45)
Final LV
geometry
Normal (n)
Concentric remodeling (n)
Eccentric LV hypertrophy (n)
Concentric LV hypertrophy (n)
12
0
4
0
4
1
2
0
31
0
39
2
19
2
18
6
66
3
73
8
B. Severely obese patients
(n Z 38)
Baseline LV geometry
Concentric
remodeling
(n Z 0)
Eccentric LV
hypertrophy
(n Z 24)
Concentric LV
hypertrophy
(n Z 13)
Final LV
geometry
0
0
0
0
4
0
20
0
Normal
geometry
(n Z 1)
Normal (n)
Concentric remodeling (n)
Eccentric LV hypertrophy (n)
Concentric LV hypertrophy (n)
1
0
0
0
2
1
7
3
7
1
27
3
Abbreviations: LV Z left ventricular.
in all BMI classes while absolute reduction in LV mass/
height2.7 was higher in overweight and obese groups (all
p < 0.01 vs. normal weight group). However, compared to
the normal weight group, the prevalence of LV hypertrophy,
predominantly of eccentric type, was 1.7 and 2.5 times
higher in the obese and morbid obese groups on final study
echocardiogram (Fig. 1). Of note, a considerable reduction
in prevalence of concentric LV hypertrophy, the prognostically most unfavorable LV geometric pattern, was also
demonstrated in the obese groups (Table 3). In multiple
regression analyses, higher baseline BMI predicted less intreatment reduction of LV mass/height2.7 (b Z 0.08),
more in-treatment reduction in LV ejection fraction
(b Z 0.07) and less improvement in midwall shortening
Table 4 Impact of BMI on in-treatment changes of LV mass/height2.7 and LV systolic function measured as ejection fraction,
midwall shortening and stress-corrected midwall shortening in multiple linear regression analyses.
Variable
In-treatment reduction in LV
mass/height2.7
In-treatment
reduction in EF
In-treatment
increase in MWS
In-treatment
increase in scMWS
Multiple R2 of model
Baseline dependent variable
BMI (kg/m2)
Age (years)
AfricaneAmerican ethnicity
Previous myocardial infarction
In-treatment decrease in LV
mass/height2.7 (g/m2.7)
In-treatment decrease in body
weight (kg)
In-treatment albuminuria
(mg/mmol)
Diabetes mellitus
Female gender
Atenolol-based treatment
0.30**
0.56**
0.10**
0.10**
0.32**
0.56**
0.08*
0.31**
0.52**
0.06*
0.07*
0.40**
0.58**
0.10**
0.07*
0.07*
0.09**
0.16**
0.06*
0.10**
0.10**
0.14**
0.07*
0.12**
0.07*
0.06*
0.13**
0.09**
0.08**
0.09**
0.07*
Abbreviations: BMI Z body mass index; EF Z ejection fraction; LV Z left ventricular; MWS Z midwall shortening; scMWS Z stresscorrected midwall shortening.
*p < 0.05; **p < 0.01.
Data are presented as Multiple R2 for individual models, and b coefficients and level of significance for independent predictors and
covariates. Additional variables that did not enter any of the models: In-treatment change in systolic blood pressure and smoking.
Cardiac benefit of BP reduction in obesity
Table 5
stroke.
127
Association between baseline BMI and rates of combined and individual cardiovascular death, myocardial infarct and
Variable
Primary composite
endpoint
(n Z 91)
Cardiovascular
death
(n Z 22)
Myocardial
infarction
(n Z 36)
Stroke
(n Z 53)
BMI (kg/m2)
In-treatment systolic blood
pressure (mmHg)
In-treatment LV mass (g)
Framingham risk score
1.05 (1.01e1.10)*
0.98 (0.97e0.99)**
1.10 (1.01e1.20)*
1.00 (0.97e1.03)
1.02 (0.95e1.10)
0.97 (0.95e0.99)**
1.04 (0.98e1.10)
0.99 (0.98e1.01)
1.00 (1.00e1.01)*
1.05 (1.03e1.07)*
1.01 (1.00e1.01)*
1.09 (1.04e1.14)**
1.01 (1.00e1.02)**
1.02 (0.98e1.05)
1.00 (0.99e1.01)
1.04 (1.01e1.07)**
Abbreviations: LV Z left ventricular; BMI Z body mass index.
*p < 0.05; **p < 0.01.
Data are presented as hazard ratio (95% confidence intervals) and significance from Cox regression analyses. Additional covariates that
did not enter any of the models: African American ethnicity and study treatment allocation.
(b Z 0.08), all (p < 0.05) independent of other covariates
including baseline LV mass/height2.7 (Table 4). Of note,
these associations remained significant also with intreatment change in body weight and prevalent and incident diabetes added to the models.
During 4.8 years follow-up, a total of 91 primary
endpoints occurred within the study population. In Cox
regression analysis, higher baseline BMI was independently
associated with a higher incidence of combined cardiovascular mortality, myocardial infarction and stroke [HR 1.05
per 1 kg/m2 higher BMI (95% CI 1.01e1.10), p Z 0.032]
which was primarily driven by higher incidence of cardiovascular mortality [HR 1.10 per 1 kg/m2 higher BMI (95% CI
1.01e1.20), p Z 0.028] (Table 5).
Discussion
The purpose of this study was to evaluate the impact of
obesity on cardiac benefit including regression of LV
hypertrophy and improvement of LV systolic function,
during systematic long-term antihypertensive treatment.
As expected from previous publications, obese patient
groups had higher prevalence of LV hypertrophy before
starting antihypertensive treatment [3e5]. However, our
findings add to previous knowledge by demonstrating that
regression of LV hypertrophy and improvement in LV
systolic function measured by echocardiography were
attenuated in obese patients in spite of comparable blood
pressure reduction induced by systematic, aggressive antihypertensive treatment. Of note, higher baseline BMI predicted less LV hypertrophy regression independent of
effects of the higher prevalence of diabetes and African
American ethnicity in the obese patient groups.
As demonstrated by our results, prevalence of residual
LV hypertrophy on the final study echocardiogram was 1.7
and 2.5 times higher in the obese and severely obese
groups, respectively, approximating the 2.7 fold higher
prevalence of LV hypertrophy associated with obesity
recently published from the observational Multi-Ethnic
Study of Atherosclerosis cohort using magnetic resonance
imaging [27]. However, a significant shift from the prognostically more severe concentric LV hypertrophy pattern
to eccentric LV hypertrophy pattern was seen during
treatment in both obese and non-obese patient groups,
consistent with a beneficial impact of antihypertensive
treatment on pressure-overload [28], while volumeoverload remained relatively unchanged as a consequence
of the small change in BMI and weight observed during
follow-up in the present study population. Of note, higher
baseline BMI predicted less LV hypertrophy regression
independent of effects of the higher prevalence of diabetes
and African American ethnicity in the obese patient
groups [29].
It is well known that obesity may promote LV systolic
dysfunction by a number of mechanisms, including comorbidities like hypertension, diabetes, coronary artery
disease or LV hypertrophy. Although LV systolic function did
not differ significantly among BMI classes in the present
study, obesity predicted less increase in midwall shortening
and more decrease in LV ejection fraction during follow-up,
independent of concomitant diabetes, history of previous myocardial infarction, African American ethnicity,
in-treatment LV mass and study treatment allocation. Our
findings add to previous epidemiologic reports from the
Olmsted County study, finding central obesity to be associated with lower LV ejection fraction and a higher risk of
development of clinical heart failure, and from a Belgian
community study finding subclinical systolic dysfunction in
obesity demonstrated by lower longitudinal strain with
higher waist-hip ratio, and lower radial strain with greater
body weight [30,31]. In the present study population, waisthip ratio and body fat distribution was not measured, thus
central obesity could not be directly studied. However,
others have demonstrated that severe obesity, corresponding to BMI 35 kg/m2, mostly is of the central type [32].
The increased morbidity and mortality observed in
obesity has often been attributed to the clustering of other
cardiovascular risk factors in obese subjects, in particular
increased prevalences of insulin resistance and type-2
diabetes [33]. As proof of concept, the Swedish Obesity
Study, which prospectively followed 2010 obese subjects
who underwent bariatric surgery to reduce weight and 2037
matched controls for 10 years, demonstrated that intentional, persistent weight reduction in obesity was not only
associated with a substantial reduction in obesityassociated cardiovascular risk factors like diabetes,
hypertriglyceridemia and hyperuricemia [34], but also with
reduced total mortality, including reduced cardiovascular
death and death from cancer [35].
128
However, others have found an independent association
between higher BMI and increased rate of cardiovascular
events, as also demonstrated by the present study results.
This was first reported more than 25 years ago from the
Framingham Heart Study [36], and more recently from
a prospective cohort study including observations from
184,697 persons in Austria [37]. In this epidemiologic study,
severe obesity was associated with a 2-fold higher risk of
cardiovascular mortality, independent of other covariates
[37]. The complex relation between body weight and
morbidity and mortality was reflected in a recent publication from the US National Center for Health Statistics [38].
In this report, obesity was particularly associated with
increased cardiovascular mortality, as well as death from
diabetes and kidney disease [38]. Findings in the present
analysis from the LIFE echocardiography substudy extend
previous LIFE publications by showing that the 11% higher
rate of cardiovascular mortality per 1 kg/m2 higher BMI was
observed despite beneficial treatment effects on echocardiographic LV mass and systolic blood pressure.
E. Gerdts et al.
[5]
[6]
[7]
[8]
[9]
Conclusions
In hypertensive patients, obesity is associated with less
regression of echocardiographic LV hypertrophy as well as
less improvement of LV systolic function during antihypertensive treatment independent of concomitant diabetes.
These findings may help explain the increased rate of
cardiovascular events observed among obese hypertensive
patients participating in the LIFE study despite a beneficial
shift from concentric to eccentric LV hypertrophy pattern.
[10]
Disclosures
[12]
E.G., K.W., K.B. and M.S.N. have all received grant support
from Merck & Co, the sponsor of the LIFE study. R.B.D. and
B.D. have received grant support and served as consultants
for Merck & Co. B.P.L. and G.d.S. have no disclosures
relating to this manuscript.
Acknowledgment
The LIFE echocardiography substudy was supported in part
by grant COZ-368 from Merck & Co, Inc., West Point, PA,
USA (the sponsor of the parent LIFE study).
[11]
[13]
[14]
[15]
[16]
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diabetes research and clinical practice 107 (2015) 37–45
Contents available at ScienceDirect
Diabetes Research
and Clinical Practice
journ al h ome pa ge : www .elsevier.co m/lo cate/diabres
Active life expectancy of Americans with diabetes:
Risks of heart disease, obesity, and inactivity
Sarah B. Laditka b,*, James N. Laditka a,1
a
Department of Public Health Sciences, and Associate Professor of Public Policy, University of North Carolina at
Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, United States of America
b
Department of Public Health Sciences, and Associate Professor of Public Policy, University of North Carolina at
Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, United States of America
article info
abstract
Article history:
Aims: Few researchers have studied whether diabetes itself is responsible for high rates of
Received 29 April 2014
disability or mortality, or if factors associated with diabetes contribute importantly. We
Received in revised form
estimated associations of diabetes, heart disease, obesity, and physical inactivity with life
23 September 2014
expectancy (LE), the proportion of life with disability (DLE), and disability in the last year of life.
Accepted 17 October 2014
Methods: Data were from the Panel Study of Income Dynamics (1999-2011 and 1986, African
Available online 23 October 2014
American and white women and men ages 55+, n = 1,980, 17,352 person-years). Activities of
daily living defined disability. Multinomial logistic Markov models estimated disability
Keywords:
transition probabilities adjusted for age, sex, race/ethnicity, education, and the health
African Americans
factors. Microsimulation measured outcomes.
Aging
Results: White women and men exemplify results. LE was, for women: 3.5 years less with
Diabetes
diabetes than without (95% confidence interval, 3.1–4.0), 11.1 less (10.3–12.0) adding heart
Disability
disease, 21.9 less with all factors (15.3–28.5), all p < 0.001. Corresponding results for men: 1.7
Mortality
years (0.9–2.3, not significant), 8.2 (6.8–9.5) and 18.1 (15.6–20.6), both p < 0.001. DLE was, for
Physical activity
women: 23.5% (21.7–25.4) with no risk factors, 27.1% (25.7–28.6) with diabetes alone, 34.6%
(33.1–36.1) adding heart disease, 52.9% (38.9–66.8) with all factors, all p < 0.001; for men:
13.2% (11.7–14.6), 16.3% (14.8-17.8, p < 0.01); and 22.1% (20.5–23.7), 36.4% (25.0–47.8), both
p < .001. Among people with diabetes, those with other conditions were much less likely to
have no disability in the final year of life.
Conclusions: Much of the disability and mortality with diabetes was due to heart disease,
obesity, and inactivity, risks that can be modified by health behaviors and medical care.
# 2014 Elsevier Ireland Ltd. All rights reserved.
1.
Introduction
About 26 million people in the United States have diabetes, a
common cause of disability and death [1]. Lifetime risk of
having diabetes is over 33% for men and 39% for women [2].
Diabetes often causes difficulty with activities of daily living
(ADLs) such as walking and dressing [3,4]. Many people with
diabetes also have heart disease, or are obese or physically
inactive. Each of those health factors reduces life expectancy
and increases the risk of disability. Those factors may
confound the association of diabetes with disability and life
* Corresponding author. Tel.: +1 704 687 5390; fax: +1 704 687 1644.
E-mail addresses: sladitka@uncc.edu (S.B. Laditka), jladitka@uncc.edu (J.N. Laditka).
1
Tel.: +1 704 687 8742; fax: +1 704 687 1644.
http://dx.doi.org/10.1016/j.diabres.2014.10.008
0168-8227/# 2014 Elsevier Ireland Ltd. All rights reserved.
38
diabetes research and clinical practice 107 (2015) 37–45
expectancy, yet no study has examined that association after
controlling for them. This study adds to knowledge about
diabetes by estimating the association of diabetes with
disability and life expectancy with and without heart disease,
obesity, and inactivity.
Heart disease is one of the most prevalent diseases in the
United States [5–7]. Diabetes causes vascular damage that
substantially increases the risk of developing heart disease,
and doubles the risk of dying from it [6–9]. It is nonetheless
useful to consider the health risks of diabetes that are
independent of heart disease because people can control
diabetes and reduce heart disease risk by avoiding smoking,
maintaining healthy weight, eating a heart healthy diet,
controlling blood pressure and low-density lipoprotein
cholesterol, and following the treatments recommended
by their physicians [6–9]. One study has examined associations of both diabetes and heart disease with life expectancy
[9]. The researchers found that although diabetes increased
heart disease risk, the substantial reduction in life
expectancy associated with diabetes was not significantly
different for those with and without heart disease [9].
However, that study represented a limited population in a
small area, measured diabetes and heart disease only every
12 years, and did not consider effects of disability on
mortality [9].
The growing prevalence of overweight and obesity is
contributing to a dramatic increase in type 2 diabetes [10–
13]. Obesity is also linked with a greater risk of disability
[3,4,14]. Results of research associating obesity with mortality
among people with diabetes are not consistent. There is
evidence suggesting an ‘‘obesity paradox,’’ higher mortality
with normal weight than with overweight or obesity for people
with diabetes [15], although a recent study did not support this
theory [16]. Some studies have found greater mortality risk
only with severe obesity [17,18]. Other researchers have found
that being physically inactive, which is common among
people who are obese, increases mortality with diabetes
[11,12,19]. No related research has measured activity and
obesity with adequate time before measuring disability to
limit the possibility that disability caused the inactivity or
obesity, rather than being caused by them. We address that
substantial research gap.
Measuring active life expectancy is a useful way to
understand effects of diabetes on health. This central measure
of population health estimates the proportions of remaining
life from a given age with and without disability, as well as life
expectancy [20,21]. Relevant studies have found that diabetes
reduces life expectancy and increases disability [22–26].
However, given substantial evidence that heart disease,
obesity, and inactivity are associated with both diabetes and
active life expectancy, we addressed two hypotheses. The first
was that people with diabetes and one or more of those health
factors would have a larger proportion of older life with
disability and shorter life expectancy than people with
diabetes alone. Thus, we hypothesized that the impact of
diabetes on disability and life expectancy would be less than
previously estimated because researchers have not controlled
for those factors. Our second hypothesis was that these
associations would last to the end of life, resulting in a
markedly smaller percentage of those with diabetes and one
or more of the other health conditions having no month of
disability in the last year of life, compared with those with
diabetes without the other factors. Researchers call this
outcome successful aging to the end of life [27].
2.
Subjects, materials and methods
2.1.
Data source and study sample
We used data from the Panel Study of Income Dynamics (PSID)
[28]. We followed a nationally representative sample ages 55
and over who identified themselves as African American or
non-Hispanic white (hereafter white) from 1999 through 2011
(n = 1,980). We excluded races/ethnicities with samples too
small for analysis (n = 78).
2.2.
Dependent variables
We identified disability from participants’ reports of having
‘‘any difficulty. . .because of a health or physical problem,’’
doing any ADL by themselves and without special equipment:
bathing, eating, dressing, getting into or out of a bed or chair,
walking, getting around outside, and getting to and using the
toilet. Death was another measured outcome. The dependent
variable indicated one of several transitions: remaining nondisabled, becoming disabled, recovering from disability,
remaining disabled, dying when non-disabled, or dying when
disabled. Each transition was defined by a participant’s
responses about each of the ADLs in a pair of successive
survey waves, or in one wave followed by death. With
responses in up to seven survey waves plus death, each
individual could have up to seven measured transitions. The
PSID identified death dates using the National Death Index,
compiled by the National Center for Health Statistics from
state vital records. The analytic data represented 9039
transitions occurring through 17,352 person-years.
2.3.
Measuring diabetes and heart disease
In all seven waves interviewers asked, ‘‘Has a doctor ever told
you that you have or had [diabetes/heart disease]?’’ Interviewers were instructed: ‘‘Do not accept self-diagnosed or
diagnosed by a person who is not a doctor or other health
professional.’’ We updated the data with each new diagnosis,
but assumed that diagnosed individuals did not recover from
the disease. We examined the consistency of disease reports
across survey waves.
2.4.
Measuring obesity
We calculated body mass index (BMI, kg/m2) using height
and weight reported by participants in 1986. We used 1986
data for BMI both to examine effects of earlier-life weight
status and to limit the likelihood that disability measured by
the outcome variable contributed to the person’s BMI. We
defined obesity as BMI 35.0, using a World Health Organization threshold. This definition identified individuals
whose BMIs were most likely to affect health, disability,
and mortality, excluding those with lower levels of obesity
diabetes research and clinical practice 107 (2015) 37–45
that may not be associated with poor health outcomes in
older populations [17,18]. We examined the sensitivity of the
results to defining obesity as BMI 30.0.
2.5.
Measuring physical inactivity
In 1986 the PSID asked, ‘‘Do you get any regular exercise, such
as doing hard physical work, or walking a mile or more
without stopping, or playing an active sport?’’ We considered
those responding negatively to be inactive. Disability reported
in 1999 would rarely cause inactivity in 1986, although
permanent disability might do so for a small number of
participants. For the few participants (n = 39) who did not
provide BMI or activity measures in 1986, we used equivalent
self-reports from 1999. We examined correlations among the
1986 obesity and activity measures with reports from that year
of having only fair or poor health, and with a measure of
disability defined by health conditions that ‘‘keep you from
doing some types of work’’ (‘‘somewhat,’’ ‘‘a lot,’’ or
completely).
2.6.
Controlling for education
We controlled for six education levels [29]: less than 8 years,
completion of grade 8, completion of grades 9 through 12
without a high school diploma, high school graduation, some
education after high school, and at least a 4-year college
degree.
2.7.
The model associating diabetes and related health
factors with disability and death
Our regression model represented increasing risks of disability
and death with age, and allowed for an accelerating increase,
including controls for: age, age-squared, age85plus, and (age85plus age), where age85plus indicated that age level (yes/no).
The latter two terms defined a spline function that allowed a
shift in disability and death risks beginning at age 85 [30]. The
model included sex, race/ethnicity (African American or
white), education, and the health factors. To provide specific
probabilities for each population, the model included all 2-way
interactions of sex and race/ethnicity with the health factors,
and all 3-way interactions of those variables. Likelihood ratio
tests indicated the interactions were significant ( p < 0.001).
2.8.
Discrete-time Markov chains
The regression model applied maximum likelihood methods
to the measured interval of each disability transition to
identify Markov chains in the observed data, estimating
disability and death transition probabilities for each month
of life conditional on all measures in the previous month.
Researchers who study active life expectancy often use this
approach [22,24–26,30–37].
2.9.
Variance-adjusted standard errors
Repeated measures for individuals in longitudinal studies
produce underestimated standard errors [30,34,38]. To account for repeated measures, we re-estimated the model with
39
a subject-specific random effect [30,34]. There is no accepted
method for adding random effects to microsimulations [39].
We therefore used the estimates from the standard regression model described in sections 2.7 and 2.8 for the
microsimulations, to which we turn in Section 2.10. However,
for covariates with larger variance in the random effect
model, we adjusted the corresponding standard errors of the
regression results to reflect that greater variance. This
procedure was analogous to standard error adjustments for
survey design effects [30,34]. It did not alter the point
estimates from the microsimulations, but did provide
considerably more conservative standard errors for those
results. Of the 80 covariates, 77 were statistically significant
(p < 0.001).
2.10.
Microsimulation
Microsimulation helps researchers understand complex phenomena that cannot be studied with more common statistical
methods. Microsimulation used the transition probabilities to
create large populations in which each individual had a
complete record of monthly disability measures from age 55
until death. The expected age at death was the average age at
death in the microsimulated population. We provide summary
results for that measure, the proportion of remaining life with
disability, and successful aging. We also exemplify the life
course successful aging results with a detailed figure for one
population, for which we used the Wilcoxon-Mann-Whitney
test to compare the distributions. We held education constant
at the high school level in the microsimulations, the most
common educational attainment of the sampled population.
Details of the methods are published [20,26,30,33–37].
2.11.
Estimating variation in the microsimulation results
We used bootstrapping to estimate variation in the microsimulation results, accounting for parameter uncertainty
(represented by 95% confidence intervals for the estimated
parameters) and the Monte Carlo variation that affects most
simulation research [30,34,35]. Bootstrapping repeated the
microsimulation for each population 500 times. For each
repetition we made a random selection for each parameter
from its variance-adjusted 95% confidence interval (CI). The
final CIs we report are the 2.5th and 97.5th percentiles of the
500 results [30,34,35]. We conducted the analyses using SAS
IML (Cary, North Carolina). The Institutional Review Board
(IRB) at the University of North Carolina at Charlotte
determined that this research, which used de-identified
secondary data, did not require IRB review.
3.
Results
3.1.
Sample characteristics
The mean age in the analytic sample was 78.3 (weighted for
national representativeness, 78.5). Women were 60.5% (59.1%).
The PSID over-sampled African Americans, who were 20.1%
(9.0%). The percentages with diabetes, heart disease, obesity,
and physical inactivity, respectively, were: 24.2% (22.5%),
40
diabetes research and clinical practice 107 (2015) 37–45
21.5% (22.4%), 7.8% (6.2%), and 8.8% (8.2%) (results not shown
in tables).
There was little evidence of correlation in the 1986
measures between inactivity and either obesity (r = 0.03,
p = 0.07), fair/poor health (r = 0.03, p = 0.12), or work disability
(r = 0.01, p = 0.39). Obesity was weakly correlated with fair/
poor health (r = 0.04, p < 0.05) and work disability (r = 0.04,
p < 0.05). Of participants with diabetes, 16% reported in a
later survey response that they did not have diabetes. These
participants confirmed the diabetes diagnosis with an average
of 3.4 survey responses, and 54% had responded that they had
the disease for more than two years. Of those reporting heart
disease, 21% reported in a later survey that they did not have
heart disease. They confirmed the diagnosis with an average
of 3.5 diagnosis reports, and 76% said that they had the disease
for more than two years.
3.2.
Patterns of active life expectancy
Table 1 shows the average age at death from age 55, and the
percentage of remaining life with disability, together with the
CIs. The estimate for people without diabetes is for those
without heart disease or earlier-life obesity or inactivity.
Compared with people without diabetes, those with diabetes
but none of the other risk factors had shorter lives and a
greater proportion of remaining life with disability. For white
women, compared to those without diabetes, the average age
at death for those with diabetes but none of the other factors
was 3.5 years less (CI 3.1–4.0, p < 0.001, difference in years not
shown in table). In the comparable result for disability, white
women without diabetes were disabled 23.5% of remaining
life (CI 21.7–25.4), those with diabetes 27.1% (CI 25.7–28.6,
p < 0.01). Among African American women the analogous life
Table 1 – Diabetes, associated factors, life expectancy and percentage of remaining life disableda
White Women
No Diabetes
Diabetes
Diabetes, Heart Disease
Diabetes, Obese
Diabetes, Inactive
Diabetes, Heart Disease, Obese
Diabetes, Heart Disease, Inactive
Diabetes, Obese, Inactive
Diabetes, Heart Disease, Obese, Inactive
African American women
No Diabetes
Diabetes
Diabetes, Heart Disease
Diabetes, Obese
Diabetes, Inactive
Diabetes, Heart Disease, Obese
Diabetes, Heart Disease, Inactive
Diabetes, Obese, Inactive
Diabetes, Heart Disease, Obese, Inactive
White Men
No Diabetes
Diabetes
Diabetes, Heart Disease
Diabetes, Obese
Diabetes, Inactive
Diabetes, Heart Disease, Obese
Diabetes, Heart Disease, Inactive
Diabetes, Obese, Inactive
Diabetes, Heart Disease, Obese, Inactive
African American Men
No Diabetes
Diabetes
Diabetes, Heart Disease
Diabetes, Obese
Diabetes, Inactive
Diabetes, Heart Disease, Obese
Diabetes, Heart Disease, Inactive
Diabetes, Obese, Inactive
Diabetes, Heart Disease, Obese, Inactive
a
Life Expectancy
(Average Age at Death)
Percent of Remaining Life
Disabled
Mean
(95% CI)
Mean
(95% CI)
88.6
85.1
77.5
84.1
69.4
76.6
65.8
70.9
66.7
(86.7–90.5)
(83.6–86.5)
(76.4–78.5)
(82.7–85.4)
(63.2–75.7)
(75.4–77.8)
(60.3–71.2)
(61.3–80.6)
(58.2–75.2)
23.5
27.1
34.6
42.1
28.4
50.8
34.6
45.9
52.9
(21.7–25.4)
(25.7–28.6)
(33.1–36.1)
(39.0–45.1)
(21.7–35.1)
(47.9–53.6)
(25.5–43.6)
(33.6–58.1)
(38.9–66.8)
85.2
82.7
75.7
83.6
66.8
76.4
64.4
70.3
67.1
(82.5–87.9)
(80.8–84.6)
(74.3–77.1)
(82.2–84.9)
(61.1–72.5)
(75.3–77.5)
(59.3–69.6)
(61.0–79.7)
(58.4–75.8)
22.5
27.0
38.3
43.6
27.3
53.6
34.8
46.3
54.5
(20.3–24.7)
(25.2–28.8)
(36.5–40.1)
(40.3–46.9)
(21.7–33.0)
(50.3–56.9)
(26.3–43.2)
(35.5–57.2)
(41.8–67.2)
83.2
81.5
75.0
82.4
64.7
75.1
62.7
68.1
65.1
(79.9–86.4)
(79.0–84.1)
(73.1–76.9)
(80.5–84.2)
(60.8–68.6)
(73.5–76.6)
(59.5–66.0)
(61.8–74.3)
(59.3–70.8)
13.2
16.3
22.1
29.2
15.0
37.4
19.7
29.4
36.4
(11.7–14.6)
(14.8–17.8)
(20.5–23.7)
(26.5–32.0)
(11.6–18.5)
(34.2–40.6)
(14.1–25.2)
(20.7–38.2)
(25.0–47.8)
77.1
76.7
71.4
79.9
61.7
73.4
60.6
65.5
63.5
(73.2–81.1)
(73.7–79.8)
(69.2–73.6)
(77.8–82.1)
(58.8–64.6)
(72.0–74.8)
(57.8–63.4)
(59.7–71.3)
(58.1–68.9)
13.5
17.4
25.1
31.6
18.7
41.8
24.7
33.1
41.7
(11.9–15.0)
(15.5–19.3)
(23.0–27.2)
(28.3–34.8)
(16.7–20.7)
(38.2–45.4)
(20.2–29.1)
(26.4–39.7)
(32.5–50.9)
Data Source: Panel Study of Income Dynamics, 1999–2011; 1986 for obesity and physical activity. CI = Confidence Interval.
41
diabetes research and clinical practice 107 (2015) 37–45
expectancy result was not statistically significant; the
analogous disability results were 22.5% (CI 20.3–24.7) and
27.0% (CI 25.2–28.8, p < 0.01). Comparing life expectancy
without diabetes to life expectancy with diabetes but no
additional risks, confidence intervals overlapped for both
African American and white men, indicating that the
comparison did not identify statistically significant differences. In the result for disability for white men, those without
diabetes were disabled 13.2% of remaining life (CI 11.7–14.6),
those with diabetes 16.3% (CI 14.8–17.8, p < 0.01). Among
African American men, those with diabetes but no other
measured risk were disabled for a greater percentage of
remaining life (17.4%, 15.5–19.3) than those without diabetes
(13.5%, 11.9–15.0, p < 0.01).
Individuals with both diabetes and either heart disease or
earlier-life inactivity had a lower average age at death than
those with only diabetes. Among white women, compared to
those with diabetes but none of the other risks, those with
diabetes and heart disease lived 7.6 fewer years (CI 7.2–8.0,
p < 0.001). Among white women with diabetes, those with
heart disease had a significantly higher percentage of
remaining life with disability (34.6%, 33.1–36.1) than those
with none of the other risks (27.1% 25.7–28.6, p < 0.001).
Analogous results for African American women for disability
also indicated additional risk with heart disease, with
disability in 38.3% of remaining life with diabetes and heart
disease (36.5–40.1) compared with 27.0% (25.2–28.8, p < 0.001)
with diabetes alone. The corresponding reductions in life
expectancy for white and African American men were also
significant, respectively 6.5 (5.9–7.2, p < 0.001) and 5.3 (4.5–6.2,
p < 0.05) years. Among white men with diabetes, those with
heart disease had a significantly higher percentage of
remaining life with disability (22.1%, 20.5–23.7) than those
with none of the other risks (16.3%, 14.8–17.8, p < 0.001);
corresponding results for African American men were: 25.1%
(23.0–27.2) and 17.4% (15.5–19.3, p < 0.001). Those with diabetes and all three risk factors had the lowest average age at
death in all populations, 21.9 fewer years (15.3–28.5) comparing white women with this combination to white women with
none of the other factors ( p < 0.001). Corresponding results
were 18.1 fewer years for African American women, 18.1 years
for white men, 13.6 for African American men (all p < .001).
There was little evidence that earlier-life obesity by itself
reduced life expectancy for those with diabetes. The confidence intervals for having diabetes and obesity overlapped
with those for having only diabetes for all populations,
indicating a lack of statistically significant differences.
However, in all populations the percentage of remaining life
with disability was significantly greater for those with diabetes
and earlier-life obesity than for those with diabetes alone.
White women who were obese in 1986 and had diabetes
during the study period were disabled 42.1% of remaining life
(CI 39.0–45.1), compared to the 27.1% reported above for those
with diabetes only (CI 25.7–28.6, p < 0.001). Corresponding
results were: for African American women, 43.6% (40.3–46.9)
versus 27.0% (25.2–28.8, p < 0.001); for white men, 29.2% (26.5–
32.0) versus 16.3% (14.8–17.8, p < 0.001); for African American
men, 31.6% (28.3–34.8) versus 17.4% (15.5–19.3, p < 0.001).
In all populations, compared to those with diabetes alone,
those with diabetes and all of the other health risks had more
disability. White women with diabetes but none of the other
risks lived 27.1% (25.7–28.6) of remaining life with disability, as
Table 2 – Successful Aging to the End of Life: Percentage of Individuals Dying at ages 84 through 86 with No Months of
Disability in the Year Preceding Death, Associations with Diabetes and Associated Factorsa
White Women
No Diabetes
Diabetes
Diabetes, Heart Disease
Diabetes, Obese
Diabetes, Inactive
Diabetes, Heart Disease, Obese
Diabetes, Heart Disease, Inactive
Diabetes, Obese, Inactive
Diabetes, Heart Disease, Obese, Inactive
Mean
(95% CI)
Mean
(95% CI)
25.1
13.9
6.3
4.3
15.6
1.6
7.3
3.9
1.3
(19.0–31.5)
(9.5–18.0)
(4.9–7.9)
(3.2–6.1)
(10.0–23.4)
(0.9–2.5)
(4.3–10.7)
(1.6–7.1)
(0.1–2.5)
32.7
18.6
8.1
5.7
17.5
2.1
1.2
0.5
1.5
(26.5–38.8)
(14.1–23.1)
(5.8–10.4)
(3.7–7.7)
(8.6–26.5)
(1.1–3.1)
(0.1–2.9)
(0.1–1.5)
(0.1–3.7)
White Men
No Diabetes
Diabetes
Diabetes, Heart Disease
Diabetes, Obese
Diabetes, Inactive
Diabetes, Heart Disease, Obese
Diabetes, Heart Disease, Inactive
Diabetes, Obese, Inactive
Diabetes, Heart Disease, Obese, Inactive
a
African American Women
African American Men
Mean
(95% CI)
Mean
(95% CI)
47.9
30.9
16.4
11.3
32.7
4.6
17.8
11.1
4.5
(39.9–54.8)
(23.7–37.3)
(12.8–20.1)
(8.0–16.3)
(25.3–42.6)
(2.9–6.7)
(11.7–25.4)
(5.2–18.4)
(2.1–7.7)
56.4
28.0
20.0
14.8
33.5
5.8
19.1
12.1
4.1
(48.9–63.8)
(17.4–38.7)
(15.1–24.9)
(9.4–20.2)
(22.8–44.1)
(3.6–8.0)
(0.1–66.7)
(3.2–21.0)
(0.1–9.9)
Data Source: Panel Study of Income Dynamics, 1999–2011; 1986 for obesity and physical activity. CI = Confidence Interval.
42
diabetes research and clinical practice 107 (2015) 37–45
Figure 1 – Diabetes, associated factors, and successful aging to the end of life. Percentage of deaths with no disability in the
last year of life, non-Hispanic whites.
reported above, compared with 52.9% (CI 38.9–66.8, p < 0.001)
for those with diabetes and all three risks. Analogous results
were: for African American women, 27.0% (25.2–28.8) versus
54.5% (41.8–67.2, p < 0.001); for white men, 16.3% (14.8–17.8)
versus 36.4% (25.0–47.8, p < 0.001); for African American men,
17.4% (15.5–19.3) versus 41.7% (32.5–50.9, p < 0.001).
3.3.
Successful aging to the end of life
Table 2 shows results for successful aging, the percentage of
individuals who died at ages 84-86 without disability in the
last year of life, and the CIs. To clarify comparisons among
groups, we describe the results from Table 2 using relative
risks, the ratio of the rate for people with diabetes to the rate
for people without diabetes. Comparing white women with
diabetes to those without diabetes, the relative risk of
having no disability in the last year of life was 0.55 (13.9/
25.1, p < 0.001, relative risks not shown in table). Thus, the
‘‘risk’’ or likelihood that women with diabetes would have
no disability in the last year of life was 45% lower than that
likelihood for women without diabetes. Corresponding risk
ratios were: 0.57 for African American women; 0.65 for
white men, and 0.50 for African American men (all
p < 0.001). The risk of disability in the last year of life was
also greater for those with diabetes and one or more of the
other risks. For all groups, among those with diabetes and
all of the other risks only a small percentage were not
disabled in the last year of life: 1.3% of white women (CI 0.1–
2.5), 1.5% of African American women (CI 0.1–3.7), 4.5%
of white men (CI 2.1–7.7), 4.1% of African American men
(CI 0.1–9.9).
Fig. 1 shows analogous percentages for white women who
died at ages 75 to 95. Having diabetes with most combinations
of the other risks substantially limited the proportion of
people without disability in the final year of life. The results at
age 75 illustrate that finding, where 43% of women without
diabetes or any of the other risks had no disability in their last
year of life, and 27% of those with only diabetes did so, both
compared to only 3% of those with diabetes and all other risks
(all p < 0.001). Women with diabetes alone were considerably
more likely to avoid disability in their last year of life than
women with diabetes and most combinations of the other
risks, an advantage that persisted throughout older life.
Results for white men and African Americans were similar
(not shown).
3.4.
Sensitivity of results to the definition of obesity
There was little evidence that obesity was associated with life
expectancy for people with diabetes (Table 1). Using BMI 30.0
to define obesity instead of BMI 35.0 did not result in
statistically significantly different estimates (results not
shown in tables). Using BMI 30.0 increased the proportion
of life with disability by 34.5% for women and 14% for men;
however, these comparisons were not statistically significant
different from those using BMI 35.0.
4.
Discussion
We studied the association of diabetes with active life
expectancy and measured the individual and combined
additional risks for people with diabetes of heart disease
and earlier-life obesity and inactivity. Consistent with previous studies, participants with diabetes had shorter lives than
others, with more disability [22–26]. Consistent with our first
hypothesis, being obese or inactive earlier in life, or having
heart disease, greatly reduced both active life and life
expectancy for people with diabetes. One of the largest
negative associations for active life and life expectancy was
diabetes research and clinical practice 107 (2015) 37–45
the combination of diabetes with having been physically
inactive 13 years before the study baseline, a result that is
consistent with previous research [11,12,19]. Also consistent
with previous studies, we found little evidence that earlier-life
obesity reduced life expectancy for those with diabetes if they
had none of the other health risks [17,18]. Considerable
evidence suggests that obesity may have limited effects on
mortality among people who maintain cardiorespiratory
fitness through regular physical activity [40]. However, among
people with diabetes those who were obese earlier in life were
disabled for a significantly greater proportion of life than those
who were not obese. Consistent with our second hypothesis,
people with diabetes were much more likely than others to be
disabled at the end of life. With any of the additional risks few
people with diabetes avoided ADL disability in their last year.
With diabetes and none of the additional risks, on the other
hand, the likelihood of being disabled in the last year of life
was considerably lower.
It is likely that diabetes was responsible for some of the
additional risks associated with heart disease because diabetes is a cause of heart disease. We examined the independent
risks of diabetes for disability and death because controlling
diabetes can limit its impact on heart disease [6–8]. It is
therefore useful to better understand disability and mortality
for people who can control their diabetes. Our finding that
having heart disease greatly reduced life expectancy for
people with diabetes was not consistent with the only
previous related study [9]. Participants in that study were
primarily non-Hispanic whites in Framingham, Massachusetts [9]. Diagnoses of diabetes and heart disease were updated
about every 12 years in that study, which may have resulted in
an underestimation of the associations between these
diseases and mortality [9]. Also the research method in that
study did not account for effects of disability on life
expectancy. Thus, differences between the two studies may
be due to substantial differences in data and methods.
4.1.
Limitations
The PSID’s diabetes question did not distinguish between type
1 and type 2. About 5% of adults with diabetes have type 1 [41].
Survival with type 1 has increased in recent decades but did
not greatly exceed age 50 in the cohort we studied [41]. Most
people with type 1 are diagnosed before age 18 [41]; 1.2% in our
sample with diabetes reported diagnoses before age 18. Thus,
few participants were likely to have had type 1. Given that the
PSID is nationally representative its distribution of diabetes
types may represent the United States population.
Diabetes and heart disease were self-reported but based on
physician diagnoses. Responses to questions about conditions
diagnosed by physicians tend to be highly correlated with
disease and physician records [3,42,43]. However, reports of
diagnoses are related to health care access and symptom
severity [42]. Health care access is related to socioeconomic
status and race/ethnicity. It is likely that controls for education
and race/ethnicity limited bias associated with socioeconomic
status, access to care, and symptom severity [29]. Our
approach assumed that people diagnosed with diabetes or
heart disease did not recover. There is evidence that these
diseases may be reversible; however, few people achieve the
43
substantial and sustained behavioral changes that are
required [44,45]. The limited number of participants with
inconsistent reporting of these diseases repeatedly said that
they had the disease. This suggests that most ‘‘recoveries’’
represented reporting error.
Height and weight were self-reported. Although many
people who are obese do not recognize that fact, self-reported
height and weight bias is limited, particularly during in-person
interviews as in the 1986 PSID [46]. The PSID is recognized for
establishing trust among participants, who report sensitive
data with item-response rates over 99% [47]. Using the 1986
BMI measure greatly increased the likelihood that it would not
be affected by disability reported in 1999. The small correlation
of this measure with work disability in 1986 suggested that
earlier functional limitation was not a notable cause of
obesity.
Individuals who said they were inactive in 1986 could
have become active before 1999, although it is more common
for people to reduce activity as they age. The small
correlation of this measure with both general health and
work disability in 1986 suggested that earlier health status
or functional limitation were not important causes of
inactivity. The activity question provided several examples
of regular exercise including ‘‘doing hard physical work,’’
and ‘‘walking a mile or more without stopping.’’ Some
participants who were active at more moderate levels may
have responded negatively to this question. The PSID did
not ask about the frequency, intensity, or duration of
activity, which are needed for precise measurements. The
existence and direction of any bias is uncertain because
of the lack of measurement specificity.
Another consideration is that African Americans may have
died at a higher rate before age 55 than whites, as African
Americans may have higher mortality until about age 70
[20,48]. This limitation affects most related studies. Our
sample included participants beginning at age 55. Related
studies typically begin at 65 or older. Our younger starting age
may have provided more valid outcome comparisons for
African Americans and whites than related studies with
older starting ages. If African Americans died at a higher rate
before age 55 than whites, and if that was due to diabetes, the
results may underestimate the effect of diabetes on mortality
for African Americans. In another area, although we used
‘‘successful aging’’ to describe having no disability in the
final year of life, we emphasize that people with disabilities
can also age successfully in many ways.
4.2.
Conclusions
We found that diabetes was associated with more disability
and shorter lives. However, much of the greater disability
and mortality among people with diabetes was attributable
to risk factors that are often associated with diabetes,
particularly heart disease and earlier-life inactivity, and,
specifically with regard to disability, obesity earlier in life.
People with diabetes who did not also have the other risks
were much more likely to age successfully to the end of life,
underscoring the positive message that healthy behaviors
and medical care may greatly improve both the length and
the quality of life for people with diabetes.
44
diabetes research and clinical practice 107 (2015) 37–45
Conflicts of Interest
The authors declare that they have no conflict of interest with
the article.
Acknowledgments
We are grateful to two anonymous reviewers for valuable
comments about this research.
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JACC VOL. 67, NO. 19, 2016
Letters
MAY 17, 2016:2310–9
endothelium of the aorta, an observation that could
support a developmental effect (5).
In conclusion, we here report on multiple families
harboring HCN4 mutations, who show significant
dilation of the aorta ascendens, besides the recently
Obesity Cardiovascular
Disease and the Failure of
Public Health Education
established combined phenotype of bradycardia,
NCCM, and mitral valve disease. These results have
The authors of the VIRGO (Variation in Recovery:
important implications for patient care and for the
Role of Gender on Outcomes of Young AMI Patients)
fundamental understanding of the role of the HCN4
study (1) deserve congratulations for their impressive
channel in health and disease.
work. The paper covers a lot of ground, but perhaps
the most important finding is the notably high prev-
Alexa M.C. Vermeer, MD
*Elisabeth M. Lodder, PhD
Dierk Thomas, MD
Floor A.M. Duijkers, MD, PhD
Carlo Marcelis, MD, PhD
Edwin O.F. van Gorselen, MD
Philipp Fortner, MD
Sebastian J. Buss, MD
Derliz Mereles, MD
Hugo A. Katus, MD
Arthur A.M. Wilde, MD, PhD
Connie R. Bezzina, PhD
S. Matthijs Boekholdt, MD, PhD
Patrick A. Schweizer, MD
Imke Christiaans, MD, PhD
*Department of Experimental Cardiology
Academic Medical Center, University of Amsterdam
Meibergdreef 15, Room K2-110
PO Box 22660
1100DD Amsterdam
the Netherlands
E-mail: E.M.Lodder@amc.uva.nl
http://dx.doi.org/10.1016/j.jacc.2016.01.086
Please note: The authors acknowledge support from the Netherlands CardioVascular Research Initiative (CVON-PREDICT project) and the German Centre
for Cardiovascular Research. Dr. Schweizer has received support from the MaxPlanck-Society (TANDEM project) and the Heidelberg Research Center for
Molecular Medicine (Senior Career Fellowship). Dr. Thomas has received support from the German Cardiac Society and the Hengstberger Foundation (KlausGeorg and Sigrid Hengstberger Scholarship) and the Joachim Siebeneicher
Foundation. The authors have reported that they have no relationships relevant
to the contents of this paper to disclose. The authors thank Dr. van SpaendonckZwarts, Dr. van Haelst, and Dr. Caliskan for additional medical information and
constructive discussions concerning this work.
REFERENCES
1. Milanesi R, Baruscotti M, Gnecchi-Ruscone T, DiFrancesco D. Familial sinus
bradycardia associated with a mutation in the cardiac pacemaker channel.
N Engl J Med 2006;354:151–7.
alence of obesity, particularly in young women.
“Obesity” is an imprecise term that reflects body
mass index, but not necessarily the deposition and
distribution of fat in metabolically sensitive body
compartments, such as the abdomen. This may
explain the confusion in the scientific community and
lay press regarding the cardiovascular risks of obesity
in women. In 1997, Barrett-Connor (2) used the term
“female pattern obesity” to describe non-visceral
adiposity. Superficial reading of this terminology
might lead some to believe that obesity is not a risk
factor for women. In fact Barrett-Connor (2) specifically hypothesized that visceral obesity is the causative factor for cardiovascular disease (CVD) and that
women with visceral adiposity are at higher risk than
men. This hypothesis has been conclusively proven.
Specific measures of visceral adiposity have been
shown to be powerful predictors of CVD in women.
What about the young women in the VIRGO study?
Did they have visceral or peripheral adiposity? Data
on waist circumference would be helpful if available.
However, we know that in young women, but not
older women, body mass index is a good predictor of
visceral adiposity (3). In the absence of any other
data, we can safely surmise that the young women
experienced visceral obesity as an important risk
factor for early CVD.
The VIRGO study also evaluated perceived risk and
health care provider discussion of risk, and it found
both wanting.
The VIRGO study reports that only 53% of the
young patients believed that they were at risk for CVD
and that obese women were significantly less likely
than obese men to recognize this risk. This represents
2. Milano A, Vermeer AMC, Lodder EM, et al. HCN4 mutations in multiple
families with bradycardia and left ventricular noncompaction cardiomyopathy.
a compelling failure of public health education. In our
J Am Coll Cardiol 2014;64:745–56.
unaware of the CVD risks of tobacco. It is shameful
3. Schweizer PA, Schröter J, Greiner S, et al. The symptom complex of familial
sinus node dysfunction and myocardial noncompaction is associated with
mutations in the HCN4 channel. J Am Coll Cardiol 2014;64:757–67.
current era, it is unlikely that there are any smokers
that the same efforts have not been put into obesity
education.
4. Campens L, Demulier L, De Groote K, et al. Reference values for echocar-
The sociological stigma of obesity may also play
diographic assessment of the diameter of the aortic root and ascending aorta
spanning all age categories. Am J Cardiol 2014;114:914–20.
a role. An obese woman is more likely to delay health
5. Liang X, Wang G, Lin L, et al. HCN4 dynamically marks the first heart field
and conduction system precursors. Circ Res 2013;113:399–407.
care if she feels that her provider holds a bias against
her weight. Similarly, physicians are less likely to
2315
2316
JACC VOL. 67, NO. 19, 2016
Letters
MAY 17, 2016:2310–9
perform diagnostic tests in obese patients based on
the assumption that symptoms are due primarily to
obesity (4). These factors are only exacerbated when
mixed messages are received regarding the CVD risks
of obesity.
This muddle of confusion and stigma leads to
denial of risk, denial of care, and ultimately, delayed
diagnosis. At Southlake Regional Health Center, we
Comparing the
ATRIA, CHADS2, and
CHA2DS2-VASc Scores
for Stroke Prediction
in Atrial Fibrillation
studied the angiographic results in 616 young women
from 2012 through 2014. In nonobese patients, the
Van den Ham et al. (1) recently compared the ATRIA
prevalence of normal coronary arteries was 22%,
(Anticoagulation and Risk Factors in Atrial Fibrilla-
whereas in obese young women, the prevalence of
tion), CHADS 2 (congestive heart failure, hyperten-
normal coronary arteries was only 14% (p ¼ 0.01).
sion, age $75 years, diabetes mellitus, prior stroke or
Similarly, 3-vessel disease was seen in 8.7% of non-
transient
obese young women compared with 16% of obese
(congestive heart failure, hypertension, age $75
young women (p ¼ 0.005). Although these data have
years, diabetes mellitus, prior stroke or transient
limitations,
relatively
ischemic attack, vascular disease, age 65 to 74 years,
delayed testing due to either health care avoidance or
female) stroke risk scores in a primary care commu-
underestimation of patient risk.
nity cohort of patients with first-diagnosed atrial
they
are
consistent
with
On the basis of the totality of evidence, the chief
ischemic
attack),
and
CHA 2DS2-VASc
fibrillation (AF) not using oral anticoagulation (OAC)
medical officer of the United Kingdom has declared
for undefined reasons. They concluded that improved
obesity to be a “national risk” (5). As a community, we
risk prediction using the ATRIA score can reduce OAC
have a duty to our patients to honestly recognize and
overuse in low-risk patients.
inform them of the risks of obesity. The VIRGO study
However, the study raises major concerns. To put
shows us that we are failing badly. Now is the time to
their findings of a 2.99% annualized rate of stroke
have an honest discussion.
(excluding transient ischemic attack and systemic
embolism) in appropriate context requires a better
*Steven E.S. Miner, MD
Lynne E. Nield, MD
characterization of the cohort (e.g., a description of on-
*Southlake Regional Health Center
dian follow-up was only 0.74 years over a 15-year study
University of Toronto
period and patients were censored if given OAC, the
596 Davis Drive
OAC prescription rate should have been shown.
Newmarket, Ontario L3Y 2P9
OAC patients from the dataset). Also, because the me-
The contemporary threshold for OAC use with non-
Canada
OACs can reasonably be decreased to an annual stroke
E-mail: sminer@southlakeregional.org
risk of approximately 1% (2). Using ATRIA in the
http://dx.doi.org/10.1016/j.jacc.2016.01.084
aforementioned study, 40% of patients were catego-
Please note: Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
rized as low-risk (i.e., an ATRIA score #5, with
REFERENCES
1. Leifheit-Limson EC, D’Onofrio G, Daneshvar M, et al. Sex differences
in cardiac risk factors, perceived risk, and health care provider
discussion of risk and risk modification among young patients with acute
myocardial infarction: the VIRGO study. J Am Coll Cardiol 2015;66:
1949–57.
2. Barrett-Connor E. Sex differences in coronary heart disease. Why are
women so superior? The 1995 Ancel Keys Lecture. Circulation 1997;95:
252–64.
3. Rankinen T, Kim SY, Perusse L, Despres JP, Bouchard C. The prediction of
abdominal visceral fat level from body composition and anthropometry: ROC
analysis. Int J Obes Relat Metab Disord 1999;23:801–9.
4. Drury CA, Louis M. Exploring the association between body weight, stigma of
obesity, and health care avoidance. J Am Acad Nurse Pract 2002;14:554–60.
annualized stroke rates of 0.40% to 1.99%), meaning
that, for example, even a 74-year-old female with
diabetes mellitus (i.e., 5 points) would not need OAC,
nor would a 64-year-old male with hypertension and
heart failure (2 points). However, a large body of evidence shows a positive net clinical benefit from OAC
in such AF patients with $1 stroke risk factors (3).
Their sensitivity analysis excluding renal dysfunction shows an unchanged performance of ATRIA, thus
suggesting that the improvement in discriminatory
ability over CHA2DS2 -VASc might be driven solely by
the inclusion of more age categories. However, if the
ATRIA “low-risk” category is restricted to stroke rates
of
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