Psychological Medicine (2010), 40, 2059–2068. f Cambridge University Press 2010 doi:10.1017/S0033291710000176 O R I G I N A L AR T I C LE Functioning and disability levels in primary care out-patients with one or more anxiety disorders C. D. Sherbourne1*, G. Sullivan1,2,3, M. G. Craske4, P. Roy-Byrne5,6, D. Golinelli1, R. D. Rose4, D. A. Chavira7,8, A. Bystritsky9 and M. B. Stein7,10 1 Health Program, RAND Corporation, Santa Monica, CA, USA South Central VA Mental Illness Research Education and Clinical Center, Central Arkansas Veterans Healthcare System, North Little Rock, AR, USA 3 Department of Psychiatry, Division of Health Services Research, University of Arkansas for Medical Sciences, Little Rock, AR, USA 4 Department of Psychology, University of California, Los Angeles, CA, USA 5 Department of Psychiatry, University of Washington School of Medicine, Seattle, WA, USA 6 Harborview Center for Healthcare Improvement for Addictions, Mental Illness and Medically Vulnerable Populations, Seattle, WA, USA 7 Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA 8 Child and Adolescent Services Research Center, San Diego, CA, USA 9 Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA 10 Department of Family and Preventive Medicine, University of California, San Diego, La Jolla, CA, USA 2 Background. Anxiety disorders are the most prevalent mental health disorders and are associated with substantial disability and reduced well-being. It is unknown whether the relative impact of different anxiety disorders is due to the anxiety disorder itself or to the co-occurrence with other anxiety disorders. This study compared the functional impact of combinations of anxiety disorders in primary care out-patients. Method. A total of 1004 patients with panic disorder (PD), generalized anxiety disorder (GAD), social anxiety disorder (SAD) or post-traumatic stress disorder (PTSD) provided data on their mental and physical functioning, and disability. Multivariate regressions compared functional levels for patients with different numbers and combinations of disorders. Results. Of the patients, 42 % had one anxiety disorder only, 38 % two, 16 % three and 3 % all four. There were few relative differences in functioning among patients with only one anxiety disorder, although those with SAD were most restricted in their work, social and home activities and those with GAD were the least impaired. Functioning levels tended to deteriorate as co-morbidity increased. Conclusions. Of the four anxiety disorders examined, GAD appears to be the least disabling, although they all have more in common than in distinction when it comes to functional impairment. A focus on unique effects of specific anxiety disorders is inadequate, as it fails to address the more pervasive impairment associated with multiple anxiety disorders, which is the modal presentation in primary care. Received 1 September 2009 ; Revised 16 December 2009 ; Accepted 20 December 2009 ; First published online 11 February 2010 Key words : Disability, functioning, multiple anxiety disorders. Background Anxiety disorders are among the most prevalent mental health disorders in the United States. About 18 % of the US population will suffer from an anxiety disorder each year and almost 29 % will experience an anxiety disorder at some point in their lives (Kessler et al. 2005a). Prior studies of patients with specific anxiety disorders show that they have large decrements * Address for correspondence : C. D. Sherbourne, Ph.D., RAND Corporation, 1776 Main Street, PO Box 2138, Santa Monica, CA 90407-2138, USA. (Email : Cathy_Sherbourne@rand.org) in functioning and well-being and increases in disability compared with those without anxiety disorders (Blazer et al. 1991 ; Massion et al. 1993 ; Schneier et al. 1994 ; Katon et al. 1995 ; Sherbourne et al. 1996 ; Hollifield et al. 1997 ; Schonfeld et al. 1997 ; Zatzick et al. 1997 ; Malik et al. 1999). These disabilities manifest themselves in the absence of desire to perform activities, interference in level of performance, and avoidance of activities. While the negative impact of anxiety is fairly well established relative to that in persons without anxiety, few studies have compared differences in functioning and disability between the anxiety disorders themselves. In addition, while individuals with more than one anxiety diagnosis appear 2060 C. D. Sherbourne et al. to have increased symptom severity (Kessler et al. 2005b), less is known about whether or not comorbidity affects levels of functioning and disability (Norberg et al. 2008), although some studies have found lower levels of quality of life in anxiety patients with co-morbid depression compared with those with anxiety alone (Stein & Kean, 2000 ; Lochner et al. 2003). A recent meta-analysis found that, compared with control samples, no particular anxiety disorder diagnosis was associated with significantly poorer overall quality of life than was any other anxiety disorder diagnosis (Olatunji et al. 2007). However, there was difficulty in comparing across studies due to the use of different clinical settings, small sample sizes for many of the specific anxiety disorders, and different measures of quality of life assessed. This paper uses a large sample of primary care patients diagnosed with one or more of four common anxiety disorders [generalized anxiety disorder (GAD), panic disorder (PD), social anxiety disorder (SAD) and post-traumatic stress disorder (PTSD)] to address these issues. Specifically, we estimate whether the relative impact of anxiety on functioning and disability is due to the principal anxiety disorder or to the co-occurrence with other anxiety disorders. In addition, we estimate the relative contribution to reduced functioning and increased disability of different combinations of anxiety disorders, controlling for the presence of co-morbid depression. We control for comorbid depression since it is one of the most burdensome disorders worldwide (Murray & Lopez, 1996). Less is known about the comparative impact of the anxiety disorders themselves. Method Sample Subjects include 1004 primary care patients with PD, SAD, GAD or PTSD enrolled between June 2006 and April 2008 in the Coordinated Anxiety Learning and Management (CALM) study. CALM is the largest randomized trial of collaborative care for anxiety disorders conducted to date (for details about the study, see Sullivan et al. 2007). It is a flexible delivery model for primary care anxiety treatment that simultaneously targets any of these four common anxiety disorders in primary care ; provides strategies to enhance patient engagement in treatment, including allowing choice of either cognitive behavioural therapy (CBT), medication, or both ; and provides the option for additional treatment over the course of 1 year in 3-month ‘ steps ’. It utilizes a web-based outcomes system to optimize treatment decisions and a computer-assisted program to allow CBT-inexperienced care managers to optimize delivery of CBT. Medication is prescribed by primary care physicians, with care manager assistance in promoting adherence, dose optimization, and medication switches/augmentation. Patient recruitment was coordinated at four sites : University of Washington at Seattle, University of California at San Diego and Los Angeles, and the University of Arkansas at Little Rock, Arkansas. Each of the four sites selected clinics in their geographic area to participate. Candidate clinics were evaluated and 17 were purposively selected based on a number of considerations, including provider interest, space availability, size and diversity of the patient population, and insurance mix (public and private). A ‘ facilitated referral ’ approach used multiple strategies to recruit subjects. Primary care providers and clinic nursing staff directly referred potential subjects, and sites actively publicized the study within each clinic, allowing for self-referral. In addition, at some sites, a simple five-question anxiety screener (Means-Christensen et al. 2006) was used to identify patients who had potential anxiety disorders. Referred subjects met with a study clinical anxiety specialist to determine eligibility for CALM. An eligible subject had to be a patient at one of the participating clinics, be aged at least 18 years old, DSM-IV criteria for GAD, PD, SAD or PTSD [based on the Mini International Neuropsychiatric Interview (MINI ; Lecrubier et al. 1997) administered by a nurse or social worker after formal training and diagnostic reliability testing], score at least 8 (moderate but clinically significant anxiety symptoms on a scale ranging from 0 to 20) on the Overall Anxiety Severity and Impairment Scale (OASIS) (Campbell-Sills et al. 2009), be willing to participate in CALM, and be able to provide written, informed consent. The MINI has been shown to have high inter-rater and test–retest reliability and good concordance with the Structured Clinical Interview for DSM Disorders (SCID) and Composite International Diagnostic Interview (CIDI) (Lecrubier et al. 1997 ; Sheehan et al. 1998). Exclusion criteria were minimal and were intended to exclude persons who would not likely benefit from the intervention or for whom the intervention could be risky. They included serious alcohol or drug use (specifically, alcohol or marijuana dependence or any other drug abuse or dependence, including methadone – 4 % were excluded for this reason), unstable medical conditions, marked cognitive impairment, active suicidal intent or plan, psychosis, or bipolar I disorder. Subjects already receiving ongoing CBT were excluded. Finally, persons without routine access to a telephone, or who could not speak English or Spanish were excluded. Of 1620 patients referred and interviewed for eligibility, 1062 were eligible and 1036 consented for the Functional impact of co-morbid anxiety disorders study. Data for the analyses in this paper are from the 1004 subjects who completed a baseline telephone questionnaire conducted by a centralized data collection facility at the RAND Corporation in Santa Monica, CA. Measures To measure functioning and disability status, we used five widely used self-report measures. Mental and physical health-related quality of life was measured using the global physical (PCS12) and mental (MCS12) health scales of the short-form 12-item Health Survey (SF-12) (Ware et al. 2002). The SF-12 summary scores have internal consistency reliability estimates of 0.89 and 0.86, exceeding the minimum standard for grouplevel comparisons and have demonstrated good validity for discriminating between groups differing in physical or mental health status (Ware et al. 2002). Norm-based scoring is used to achieve a mean of 50 (S.D.=10) in the general US population for each measure. The three-item Sheehan Disability Index was used to measure the extent to which work/school, social life and home life or family responsibilities were impaired by the patient’s symptoms (Sheehan, 1983). The internal consistency of the measure has been shown to be high (0.83) in primary care patients and it has been shown to be a sensitive tool for identifying primary care patients with mental health-related functional impairment (Leon et al. 1997). A more direct activity limitation measure was the Centers for Disease Control and Prevention Healthy Days measure (HD3-Day), a single-item estimate of restricted activity days or days (in the past 30 days) in which poor physical or mental health kept the subject from doing usual activities (Centers for Disease Control and Prevention, 2000). A number of studies have demonstrated the construct and known-groups validity of this measure in various populations (Moriarty et al. 2003). Finally, the five-item EuroQol preference-based measure that evaluates health-related quality of life in the areas of mobility, self-care, usual activities, pain/ discomfort and anxiety/depression (EQ-5D ; Rabin & de Charro, 2001) was used to describe the patient’s health status and preference for that health state on a scale of 0 to 1. A high score on this measure indicates greater preference for one’s own current health state across the domains of physical, mental and social functioning. A wide range of studies has reported on the reliability and validity of the EQ-5D in countries around the world (Brooks et al. 2003). While the five measures are moderately correlated in our sample (e.g. the highest correlation is x0.64 between MCS12 and the Sheehan Disability Index), each provides unique information. MCS12 and PCS12 indicate 2061 more subjective reports of functioning or well-being, while the Sheehan Disability Index and HD3-Day measures (correlation=0.54) indicate disability more directly. To test whether the effect of having one or more anxiety disorders was due to increased avoidance behavior or frequency/severity of anxiety, we included three OASIS items in our analyses : How often did you avoid situations, places, objects, or activities because of anxiety or fear ? (avoidance item) ; How often have you felt anxiety ? (frequency item) ; How intense or severe was your anxiety ? (severity item) (CampbellSills et al. 2009). All multivariate analyses controlled for demographics (age, gender, education, ethnicity), number of self-report chronic medical conditions (asthma, high blood sugar or diabetes, hypertension or high blood pressure, arthritis or rheumatism, cancer, neurological condition, stroke or major paralysis, heart attack, back problems, stomach ulcer, chronic inflamed bowel, thyroid disease, kidney failure, migraine headaches, trouble seeing even with glasses, chronic lung disease, a physical disability), co-morbid depression, and study site. Statistical approach Linear multivariate regression models were run to evaluate whether levels of functioning and disability were significantly different in subjects with one or more anxiety disorders (e.g. subjects with one, two or three or more disorders), controlling for demographics, number of chronic medical conditions, co-morbid depression, and study site. To examine whether avoidance or increased frequency and severity of anxiety explained these results, we conducted additional analyses adding the avoidance item singly to the multivariate regression models and then repeated the analyses with all three OASIS items in the model simultaneously. Similarly, linear multivariate regression models were run to evaluate the unique effect of PD, SAD and PTSD, entered simultaneously, compared with GAD also controlling for the other covariates. GAD was selected as the comparator because it was the most frequent anxiety disorder. Evidence of an independent burden of disability for each anxiety disorder, after adjusting for other disorders simultaneously, provides additional support for increased burden due to co-morbidity. To determine the relative contribution to reduced functioning and well-being of different combinations of anxiety disorders, regression models were subset to patients with one anxiety disorder only ; two disorders ; and three disorders. Indicators for type of disorder or combinations of disorders were included as independent variables in the relevant 2062 C. D. Sherbourne et al. subset models, again controlling for covariates described above. Results are standardized predictions generated from parameter estimates in each regression model. Results The baseline sample of 1004 subjects was 71 % female, 20 % Hispanic, 12 % black, 57 % white, and 12 % other ethnicity. A proportion of 22 % of the sample had not completed high school. The mean age was 43 years. Of the sample, 42 % had one anxiety disorder only ; 38 % had two ; 16 % had three ; and 3 % had all four anxiety disorders. On average, the baseline sample reported 2.3 (out of 17) co-morbid chronic medical conditions. A proportion of 63 % were currently taking a prescribed psychotropic medication. Table 1 describes the sample in terms of associated co-morbid depression. As number of anxiety disorders increased, so did the percentage with co-morbid depression. For example, 56 % of those patients with only one anxiety disorder had co-morbid depression compared with 88 % of those patients with four anxiety disorders. Co-morbid depression varied from 64 % in subjects with PD to 85 % in subjects with PTSD (with or without another anxiety disorder). Table 2 shows baseline levels of functioning and well-being for all CALM subjects combined. For comparison purposes, the last column indicates general population means based on published literature. On all but physical health, CALM subjects showed reduced levels of functioning and well-being and/or increased levels of disability from those normally found in general populations. Table 3 shows baseline levels of functioning and well-being by number of co-morbid anxiety disorders. Functioning and preferences for health states decrease while activity limitations and disability increase as number of anxiety co-morbidities increase. Almost all comparisons are significantly different from one another except that patients with between two and four anxiety disorders have similarly low levels of mental well-being, and patients with one or two anxiety disorders have similarly high levels of physical functioning. The number of co-morbid anxiety disorders correlated 0.13 with the OASIS frequency item, 0.19 with the OASIS severity item, and 0.24 with the OASIS avoidance item. When the OASIS avoidance item was included in the models, nine out of the 12 significant comparisons shown in Table 3 remained significant. The differences between patients with two anxiety disorders and those with three or four disorders were reduced for the two disability measures (Sheehan Disability Index and HD3-Day), while the difference Table 1. Co-morbid depression by number and type of anxiety disorder n ( %) Proportion with MDD ( %) No. of anxiety disorders One Two Three Four 421 (42) 387 (38) 162 (16) 34 (03) 56 64 81 88 Type of anxiety disorder PD GAD SAD PTSD 475 (47) 756 (75) 405 (40) 181 (18) 64 68 69 85 MDD, Major depressive disorder ; PD, panic disorder ; GAD, generalized anxiety disorder ; SAD, social anxiety disorder ; PTSD, post-traumatic stress disorder. between patients with one disorder only and those with two disorders was also reduced for the HD3-Day disability measure. When the OASIS frequency and severity items were included along with avoidance, two more comparisons became non-significant : the difference between patients with one and two disorders on the EQ-5D and the difference between patients with one and three or four disorders on the MCS12. Table 4 shows parameter estimates from regression models where PD, SAD and PTSD were entered simultaneously with GAD, the most prevalent disorder, as the comparator. Patients with SAD had significantly lower mental functioning relative to GAD, controlling for the other anxiety disorders, depression, chronic medical conditions and demographics. Patients with either PD or PTSD had significantly lower physical functioning relative to GAD. Disability was significantly less in GAD compared with each of the other anxiety disorders, while preference for current health state was significantly higher/better in GAD compared with each of the other anxiety disorders. Table 5 shows baseline levels of functioning and well-being among patients with only one anxiety disorder, with two disorders or with three disorders. There were few large differences among these patients. Among patients with only one disorder, those with PD reported the highest level of mental well-being but the lowest level of physical functioning. Patients with SAD had the highest disability levels and, along with patients with PTSD, the most days of activity limitation due to health. Among patients with two anxiety disorders, those with PD co-morbid with SAD appeared worse off on Functional impact of co-morbid anxiety disorders 2063 Table 2. Baseline levels of functioning and well-being for CALM subjects (n=1004) Measurea Range Mean for CALM subjects (S.D.) General population mean Mental Health SF-12 composite (+)b Physical Health SF-12 composite (+)b Sheehan Disability Index (x)c Days of Activity Limitation (x)d EuroQol EQ-5D (+)e 0–100 0–100 0–30 0–30 0–1 31.8 (10.0) 49.2 (11.5) 17.0 (7.3) 11.3 (9.8) 0.67 (0.20) 50 50a 5–6 2.2 0.87 CALM, Coordinated Anxiety Learning and Management ; S.D., standard deviation ; SF, short-form. a The x or + indicates the direction of good health. b The Mental and Physical Health composite scores reflect norm-based scoring where the mean of the general population is 50 with a standard deviation of 10. c Primary care population norms (Leon et al. 1997 ; Olfson et al. 1997). d 2008 Nationwide mean days of activity limitation (confidence interval 2.1–2.3) are available on the Centers for Disease Control and Prevention (2009) website. e US general population mean (Luo et al. 2005). Table 3. Functioning and well-being levels by number of anxiety disordersa Number of anxiety disorders Measureb One Two Three or four Mental Health SF-12 composite (+) Physical Health SF-12 composite (+) Sheehan Disability Index (x) Days of Activity Limitation (x) EuroQol EQ-5D (+) 33.1 (0.4)c 50.3 (0.5)d 15.5 (0.3) 10.1 (0.4) 0.699 (0.009)i 31.3 (0.4) 49.0 (0.5) 17.5 (0.3)e 11.4 (0.5)g 0.664 (0.009)j 30.1 (0.6) 47.3 (0.7) 19 (0.5)e,f 13.6 (0.7)h 0.605 (0.014) SF, Short-form. Values are given as mean (standard error). a Analyses controlled for age, gender, education, ethnicity, number of self-report chronic medical conditions, co-morbid depression and study site. b The x or + indicates the direction of good health. c Significantly higher than subjects with two (p=0.004) or three or four (p=0.002) anxiety disorders. d Significantly higher than subjects with three or four (p=0.001) anxiety disorders. e Significantly higher than subjects with one (p=0.00001) anxiety disorder. f Significantly higher than subjects with two (p=0.0103) anxiety disorders. g Significantly higher than subjects with one (p=0.0428) anxiety disorder. h Significantly higher than subjects with one (p
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