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.