Description
To review and analyze a research study on Factors Associated with Early Mortality Among Patients with De Novo Metastatic Breast Cancer: A Population-Based Study. Please see the attached files for the research study and the instructions.
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Running head: CRITICAL REVIEW AND ANALYSIS
CRITICAL REVIEW AND ANALYSIS
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Running head: CRITICAL REVIEW AND ANALYSIS
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Critical Review and Analysis
Part I: Study Summary
Study Objective
Some patients with metastatic breast cancer experience early death after diagnosis despite
the enhanced improvements in survival for these patients. The researchers postulate that breast
cancer is one of the leading causes of death for women in the United States. Annually, there are
approximately 40,000 breast cancer deaths reported. The objective of this population-based study
was to examine the factors associated with the early deaths of patients diagnosed with metastatic
breast cancer. Therefore, the study’s purpose is to shed more light on the rates of early breast
cancer death as well as the factors associated with early death in the metastatic setting, especially
for individuals treated outside of the clinical trial setting.
Primary Exposure and Outcome of Interest
The primary exposure of interest was all the women who were diagnosed with metastatic
breast cancer between January 1, 2000 and June 30, 2011, about 26,538 women. The end date
was selected in order to have at least 6 months of substantial follow-up for all the patients,
because death was ascertained through the end of 2011. The group was then narrowed down to
4167 women who were diagnosed between January 1, 2010 and June 30, 2011. The primary
outcome of interest was early, all-cause death. The vast majority of deaths were from breast
cancer even though the interest was on the overall outcomes. For the purposes of clarity, early
death was described as any death that occurred within the first month after the respective
diagnosis.
Study Design
Running head: CRITICAL REVIEW AND ANALYSIS
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The study used Surveillance, Epidemiology, and End Results (SEER) data to identified
26,538 patients with de novo metastatic breast cancer diagnosed between January 1, 2000 and
June 30, 2011. The time trends for deaths was evaluated at 1 and 6 months after the diagnosis.
The group was then restricted to 3,317 patients diagnosed between 2010 and 2011 during which
the human epidermal growth factor receptor 2 was routinely collected. The factors associated
with early death were then examined.
Statistical Analysis
All the statistical analyses were conducted using SAS version 9.4. In examining the
proportion of women who experienced early death within 1 month and 6 months of diagnosis by
year of diagnosis during 2000–2011, the Cochran-Armitage trend test was applied, where it
tested for the changes in death rates over time. In examining the factors associated with early
death, the chi-square test was used to establish the proportion of early deaths by the independent
variables. Generalized estimating equations was used in separate logistic regression models to
account for clustering within the SEER registry. Time to events models were used in calculating
the proportion of women experiencing early death by tumor subtype and the insurance status
combined in order to demonstrate the range of proportion early death in the first month as well as
within 6 months.
The potential confounders included performance status, comorbidities, socioeconomic
environments, and granular information on patients’ burden of disease, as well as crucial
information on the treatments received, treatment decisions, the respective health care facilities,
and provider characteristics. Matching was the technique used to minimize their affects. The
potential effect modifiers include the lead time bias, which mainly relate to the aspect the timing
for the diagnosis because the diagnosis time influences the tumor burden on the patient.
Running head: CRITICAL REVIEW AND ANALYSIS
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Summary of Major Study Results
It was established that 15.9 percent of the patients died within 1 month of diagnosis and
33.2 percent died within 6 months in 2000. In 2011, the proportion of those patients dying within
1 month reduced to 13.4 percent and 26.3 percent within 6 months. The uninsured status as well
as older age were associated with early death. In addition, in some subgroups such as those that
had no insurance and the ones with triple negative disease, more than half of patients passed on
within 6 months. It was established that region was also associated with the early death of
patients.
Part II: Critical Analysis
Discussion of Random Error
In essence, random error may be described as the divergence due to chance alone, of an
observation on the sample from the true pop...