Adiposity and Hot Flashes in Midlife Women: A Modifying Role of Age

Abstract

The nature of the relationship between adiposity and hot flashes has been debated, but it has not been examined using physiological measures of hot flashes. We examined associations between body size/composition and physiologically assessed hot flashes among women with hot flashes. A subcohort of women in the Study of Women's Health Across the Nation (n = 52; 25 African-American and 27 non-Hispanic Caucasian; ages, 54 to 63 yr) who reported hot flashes, had their uterus and ovaries, and were not taking medications impacting hot flashes were recruited in 2008-2009. Women completed anthropometric measures [bioimpedance analysis of total percentage of body fat, body mass index (BMI), waist circumference], a blood draw (estradiol, SHBG, FSH, dehydroepiandrosterone sulfate), and 4 d of ambulatory sternal skin conductance monitoring with diary (physiological and reported hot flashes, respectively). Associations between anthropometrics and hot flashes were estimated with generalized estimating equations with covariates age, race, and anxiety. Higher BMI (odds ratio, 0.97; 95% confidence interval, 0.94-0.99; P < 0.05) and waist circumference (odds ratio, 0.98; 95% confidence interval, 0.97-0.99; P < 0.01) were associated with fewer physiological hot flashes. Interactions by age (P < 0.05) indicated that inverse associations of body fat, BMI, and waist circumference with hot flashes were most apparent among the oldest women in the sample. Estradiol and SHBG reduced but did not eliminate age-related variations in relations between body size/composition and hot flashes. Higher adiposity was associated with fewer physiological hot flashes among older women with hot flashes. A modifying role of age must be considered in understanding the role of adiposity in hot flashes.