The association between height-indexed skeletal muscle mass and cardiometabolic multimorbidity is largely accounted for by body mass index: findings from an older UK cohort.

Several studies suggest that higher skeletal muscle mass (SMM) may be associated with a lower risk of adverse cardiometabolic outcomes. However, the relationship between SMM and cardiometabolic multimorbidity (CMM) has not been evaluated. We investigated the prospective association between height-indexed SMM and CMM risk in an older population. Data were analyzed from 3348 participants (mean age 64 years; 45.1% men) in the English Longitudinal Study of Ageing who were free of hypertension, coronary heart disease, diabetes, and stroke at baseline (wave 4, 2008-2009). Height-indexed SMM was derived from body weight, height, age, and sex. CMM was defined at wave 10 (2021-2023) as the presence of two or more of the following conditions: hypertension, cardiovascular disease, diabetes, or stroke. Odds ratios (ORs) and 95% confidence intervals (CIs) for CMM were estimated. During 12-15 years of follow-up, 197 cases of CMM were recorded. Following adjustment for established and emerging cardiometabolic risk factors, higher height-indexed SMM was associated with an increased CMM risk (per 1 standard deviation increase: OR 1.38, 95% CI 1.12-1.68; highest versus lowest tertile: OR 1.87, 95% CI 1.07-3.27). However, this association was attenuated to null after further adjustment for body mass index (BMI), with similar attenuation observed when waist circumference (WC) was used as an alternative measure of adiposity. In this cohort of older adults from the UK, higher height-indexed SMM was associated with an increased CMM risk; however, the association was largely explained by adiposity, as reflected by both BMI and WC.