Factors Associated with 10-Year Declines in Physical Health and Function among Women during Midlife

Importance: Women in midlife often develop chronic conditions and experience declines in physical health and function. Identifying factors associated with declines in physical health and function among these women may allow for targeted interventions. Objective: To examine the factors associated with clinically important 10-year declines in the physical component summary score (PCS) of the Short Form 36 (SF-36), a widely used patient-reported outcome measure, in women in midlife. Design, Setting, and Participants: This longitudinal cohort study collected data from geographically dispersed sites in the US. Participants were part of the Study of Women's Health Across the Nation (SWAN), a racially and ethnically diverse cohort of women enrolled at or immediately before the menopause transition. Women have been followed for up to 21 years, between 1996 and 2016, with annual visits. Data were analyzed from October 2020 to March 2021. Exposures: Demographic indicators, health status measures, and laboratory and imaging assessments. Main Outcomes and Measures: The main outcome was a clinically important decline (≥8 points) on the PCS, based on the 10-year difference in scores between ages 55 and 65 years. Results: From the SWAN cohort of 3302 women, 1091 women (median [IQR] age, 54.8 [54.3-55.4] years; 264 [24.2%] Black women; 126 [11.6%] Chinese women; 135 [12.4%] Japanese women; 566 [51.9%] White women) were eligible for analyses based on duration of follow-up and availability of SF-36 data. At age 55, women had a median (IQR) body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) of 27.0 (23.2-32.6), a median (IQR) baseline PCS of 53.1 (46.8-56.7), 108 women (9.9%) were current smokers, and 938 women (86.3%) had at least 1 comorbidity. Between ages 55 and 65 years, the median (IQR) change in PCS was-1.02 (-6.11 to 2.53) points with 206 women (18.9%) experiencing declines of 8 points or more. In multivariable models, factors associated with clinically important decline included higher baseline PCS (odds ratio [OR], 1.08; 95% CI, 1.06-1.11), greater BMI (OR, 1.06; 95% CI, 1.03-1.09), less educational attainment (OR, 1.87; 95% CI, 1.32-2.65), current smoking (OR, 1.93; 95% CI, 1.14-3.26), osteoarthritis (OR, 1.46; 95% CI, 1.01-2.09), clinically significant depressive symptoms (OR, 2.03; 95% CI, 1.34-3.09), and cardiovascular disease (OR, 2.06; 95% CI, 1.26-3.36). Conclusions and Relevance: In this cohort study, clinically important declines in women's physical health and function were relatively common between ages 55 and 65 years. Several variables associated with these declines were identified as potentially useful components in a clinical score identifying women at increased risk of physical health and functional declines.