Primary care research can encompass not only a broad range of topics, but also a variety of methodologies, one being secondary data analysis. Secondary data analysis involves the analysis of existing data to evaluate questions not addressed by the original study, and can be used by primary care researchers to conduct clinical, epidemiological, and health services research. The use of secondary data analysis can have several advantages, as it can provide access to large sample sizes in a quick and inexpensive manner. However, the data available is often limited by the measures included in the original study. A variety of sources for secondary data are available, such as the Women’s Health Initiative. The Women’s Health Initiative is an ongoing study of a multiethnic cohort of postmenopausal women from 40 centers in the United States. This study is in its second extension and has over 15 years of cumulative data. Its present focus is on healthy aging, natural history of multiple chronic diseases, symptoms, and functional status. It is thus an ideal cohort for primary care researchers interested in these outcomes. One of the distinguished papers presented at the 40th NAPCRG Annual Meeting in the fall of 2012, reported successfully performed secondary data analysis of the Women’s Health Initiative. The distinguished paper, entitled Social Support and Physical Activity as Moderators of Life Stress in Predicting Baseline Depression and Change in Depression Over Time in the Women’s Health Initiative, was presented by primary care researcher Lisa Uebelacker, PhD, from Brown University.
Uebelacker’s research expands on previous research that has shown negative life events, acute stressors and chronic stressors increase risk for onset, persistence, or worsening of depression. Different types of stressors may increase risk for depression. These include interpersonal stressors, such as verbal abuse, physical abuse, social strain, care giving, or negative interpersonal life events; financial stressors such as low income or self-report of financial stress; and medical stressors such as chronic medical conditions or pain. In contrast, social support and physical activity may decrease the risk of depression. The purpose of this analysis was to determine whether social support and/or physical activity actually buffer the association between stressors and increased risk of depression symptoms at a single time point and after a 3-year follow-up period.
Uebelacker and colleagues conducted a secondary analysis of data from the Women’s Health Initiative Observational Study. This prospective cohort includes 92,063 community-dwelling post-menopausal women who participated in the study. Depression symptoms were measured at baseline and 3 years later; social support, physical activity, and stressors were measured at baseline. For baseline analyses, the investigators used the entire sample; in order to look at new-onset depression at 3-year follow-up, they used data only from the 68,368 women who were not depressed at baseline and provided follow-up data. They conducted adjusted logistic regressions, with depression status as the dependent variable.
Stressors at baseline, including verbal abuse, physical abuse, care giving, social strain, negative life events, financial stress, low income, acute pain, and a greater number of chronic conditions, were all associated with higher levels of depression symptoms at baseline and new onset elevated symptoms at 3-year follow-up. Social support and physical activity were associated with lower levels of depressive symptoms at baseline and at 3-year follow-up. Social support at baseline attenuated the association between concurrent depression and physical abuse, number of medical conditions, financial stress, social strain, and low income. Social support also attenuated the association between financial stress and low income on new-onset depression 3 years later. Physical activity was not a significant effect moderator.
These results highlight the important role that social support can play in reducing risk of depression in older women, particularly in times of stress. Although physical activity did not buffer the effects of stress on depression, investigators did find a main effect for physical activity, such that those women with increased physical activity were less likely to develop high levels of depression symptoms 3 years later.
Data from the Women’s Health Initiative (WHI) is available for review at the WHI website: http://www.whi.org. Ancillary study proposals, joining working groups, writing groups, and new paper proposals are actively supported by principal investigators at most of the 40 sites. Dr. Charles B. Eaton, senior author on the above paper, is the Principal Investigator at the Brown University, Pawtucket WHI site, and is glad to support any NAPCRG affiliated investigator interested in the WHI datasets. E-mail: charles_eaton{at}mhri.org.
- © 2013 Annals of Family Medicine, Inc.