Cross‐Sectional Associations of Body Mass Index With Disability Across High‐ and Middle‐Income Countries in 2002–2006 and 2015–2018

Introduction We examined the cross‐sectional association of BMI with limitations in instrumental (IADL) and basic (ADL) activities of daily living in surveys from middle‐ and high‐income countries in 2015–2018; we also compared changes in these associations from 2002–2006 to 2015–2018. Methods Data at the 2015–2018 wave were available on 152,856 participants aged ≥ 50 years in seven nationally representative surveys from middle‐ (Mexico, India, and China) and high‐income (the United States, SHARE–European countries, Israel, the United Kingdom, and Korea) countries. BMI was measured or self‐reported, and disability in IADL and ADL was defined as limitations in at least one out of five items, respectively. Results The prevalence of underweight in men/women ranged from 0.5/1.5 (UK) to 23.4%/20.6% (India), and that of obesity from 0.7/1.5 (Korea) to 35.6%/37.6% (US), respectively. Meta‐analyses showed underweight to be associated with a higher odds ratio (95% CI) of IADL (men, 1.78[1.26, 2.52]; women 2.07[1.38, 3.10]) and ADL (men, 1.89[1.22, 2.91]; women 1.72[1.16, 2.53]) disability. Obesity was associated with lower IADL limitations among men (0.80 [0.67–0.96]) but not among women (1.18 [0.94–1.49]), and with higher ADL (men, 1.38 [1.14, 1.65]; women, 1.59 [1.37, 1.84]). Associations of underweight with IADL and ADL, and obesity with ADL were stronger in high‐income countries. The association of BMI categories with IADL/ADL was similar in the 2002–2006 data, although the prevalence of obesity was higher in 2015–2018. Conclusion Both underweight and obesity are associated with higher IADL and ADL disability; the stronger associations in high‐income countries require further research.