Changes in Body Mass Index and Obesity Risk in Married Couples Over 25 Years: The ARIC Cohort Study

Abstract

Married couples might be an appropriate target for obesity prevention interventions. In the present study, we aimed to evaluate whether an individual's risk of obesity is associated with spousal risk of obesity and whether an individual's change in body mass index (BMI; weight in kilograms divided by height in meters squared) is associated with spousal BMI change. We analyzed data from 3,889 spouse pairs in the Atherosclerosis Risk in Communities Study cohort who were sampled at ages 45-65 years from 1986 to 1989 and followed for up to 25 years. We estimated hazard ratios for incident obesity by whether spouses remained nonobese, became obese, remained obese, or became nonobese. We estimated the association of participants' BMI changes with concurrent spousal BMI changes using linear mixed models. Analyses were stratified by sex. At baseline, 22.6% of men and 24.7% of women were obese. Nonobese participants whose spouses became obese were more likely to become obese themselves (for men, hazard ratio = 1.78, 95% confidence interval: 1.30, 2.43; for women, hazard ratio = 1.89, 95% confidence interval: 1.39, 2.57). With each 1-unit increase in spousal BMI change, women's BMI change increased by 0.15 (95% confidence interval: 0.13, 0.18) and men's BMI change increased by 0.10 (95% confidence interval: 0.09, 0.12). Having a spouse become obese nearly doubles one's risk of becoming obese. Future research should consider exploring the efficacy of obesity prevention interventions in couples.

Keywords: change; cohort study; obesity; spouses.

Figure 1.

Linear associations between changes in participants’ body mass indices and concurrent changes in spousal body mass indices, Atherosclerosis Risk in Communities Study, 1987–2013. Analyses are shown for men (A) and women (B), overall and by subgroup. β coefficients represent the change in body mass index associated with a 1-unit increase in a spouse's body mass index change. P values are for the interaction between each baseline characteristic and change in spousal body mass index. Models were adjusted for the following time-varying individual characteristics and spousal behaviors: age, time between visits, race, study site, employment, educational level, smoking status, calorie intake, cardiovascular diet score, alcohol intake, leisure and sport physical activity level, coronary heart disease, hypertension, diabetes, cancer, and lung disease. The models were not adjusted for the stratification variables.