Association between weight-adjusted waist index and cardiometabolic multimorbidity in older adults: Findings from the English Longitudinal Study of Ageing.

Abstract

The weight-adjusted waist index (WWI) is a novel anthropometric measure designed to better reflect central obesity than traditional indices such as body mass index and waist circumference (WC). This study examined the prospective association between WWI and cardiometabolic multimorbidity (CMM) and evaluated its predictive utility. We included 3,348 participants (mean age 63 years; 45.1% male) from the English Longitudinal Study of Ageing who were free from hypertension, coronary heart disease, diabetes, and stroke at baseline (wave 4: 2008-2009). WWI was calculated as WC (cm) divided by the square root of body weight (kg). CMM was defined as the presence of ≥ 2 of the following conditions at wave 10 (2021-2023): hypertension, cardiovascular disease, diabetes, or stroke. Multivariable logistic regression and measures of discrimination were used to assess associations and predictive value. Over 15 years, 197 participants developed CMM. Restricted cubic spline analysis indicated a linear dose-response relationship between WWI and CMM risk (p for nonlinearity = .44). Each 1 SD increase in WWI was associated with higher odds of CMM (odds ratio, OR = 1.30; 95% CI: 1.12-1.51), persisting after adjustment for physical activity (OR = 1.28; 95% CI: 1.10-1.49). Similar associations were observed across WWI tertiles. Adding WWI to conventional risk models slightly improved discrimination (ΔC-index = 0.0065; p = .29), with a significant improvement in model fit (-2 log likelihood, p = .001). Higher WWI levels were independently and linearly associated with increased CMM risk in older adults. WWI also improved CMM risk prediction beyond conventional risk factors.