The weight-adjusted waist index predicts sarcopenia in community-dwelling older adults in a nationwide multicenter prospective study

The weight-adjusted waist index (WWI) is recognized as an indicator of age-related changes in body composition. This study aimed to investigate the impact of WWI on the development of sarcopenia in community-dwelling older adults. A total of 1,724 individuals aged 70-84 years without sarcopenia at baseline (defined by AWGS 2019 criteria) from the Korean Frailty and Aging Cohort Study were followed for two years. WWI was calculated as waist circumference (cm) divided by the square root of body weight (kg). Muscle mass was assessed using appendicular skeletal muscle mass adjusted for body mass index (ASM/BMI), and muscle strength was measured by handgrip strength (HGS). WWI was negatively associated with ASM/BMI (r = -0.354, P < 0.001) and HGS (r = -0.075, P = 0.002), as determined by Spearman partial correlation analysis adjusted for age and sex. During the two-year follow-up, 167 participants (9.7%) developed sarcopenia. Participants in the highest quartile of baseline WWI had a significantly higher risk of developing sarcopenia compared to those in the lowest quartile (OR 2.03, 95% CI [1.24, 3.32]), after adjusting for age, sex, current smoking, regular drinking, low physical activity, low income, hypertension, diabetes, dyslipidemia, and chronic kidney disease, HOMA-IR, hs-CRP, and 25(OH)-vitamin D. A higher baseline WWI was found to be an independent risk factor for the development of sarcopenia in older adults. WWI may serve as a simple and clinically useful tool for early identification of older adults at risk for sarcopenia.