Abstract
OBJECTIVES: Sarcopenia is a condition associated with progressive loss of skeletal muscle mass and function resulting in substantial negative health outcomes and disability in older adults. It is thus important that sarcopenia-related risk factors be explored. The present study was based upon the Asian Working Group on Sarcopenia 2019 (AWGS2019) criteria to assess whether vitamin D levels are a risk factor associated with sarcopenia in various ethnic groups in western China. DESIGN: Cross-sectional study. SETTING: Communities in Yunnan, Guizhou, Sichuan, and Xinjiang provinces. PARTICIPANTS: We included 4236 individuals that were 50 years of age or older from the West China Health and Aging Trend (WCHAT) study. MEASUREMENTS: An InBody 770 instrument was used for bioimpedance-based analyses of muscle mass, while a digital grip strength dynamometer was used for handgrip strength-based measurements of muscle strength. Physical performance was assessed based upon gait speed over 4 m. Other secondary variables were additionally analyzed as potentially relevant risk factors. RESULTS: Sarcopenia affected an estimated 22.45% of studied individuals who were 50 years of age or older, with respective prevalence rates in the < 60, 60-64, 65-79, and ≥80 age groups of 11.78%,19.44%, 32.65%, and 67.97%. Rates in males and females were 26.66% and 20.05%, respectively. In males, a significant difference in vitamin D levels was detected when comparing individuals with and without sarcopenia, although no such relationship was detected in females. Following adjustment for confounding variables, binary logistic regression analyses revealed that inadequate vitamin D was able to independently predict sarcopenia risk only in males (OR=1.875,95%CI: 1.109-3.169, P=0.019). CONCLUSIONS: Among middle-aged and older adults of multiple ethnicities in western China, we found that inadequate vitamin D was an independent predictor of sarcopenia risk specifically in males.