The Relationship Between Sarcopenia and Vitamin D Levels in Adults of Different Ethnicities: Findings From the West China Health and Aging Trend Study 

Abstract

Objective: 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. The present study was designed to identify risk factors associated with sarcopenia incidence in various ethnic groups in Western China based upon the Asian Working Group on Sarcopenia 2019 (AWGS2019) criteria in various ethnic groups in Western China and to explore the relationship between sarcopenia and vitamin D levels. Study design: A cross-sectional study of individuals that were 50 years of age or older (n = 4236) from the West China Health and Aging Trend (WCHAT) study. Primary outcome and measures: 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 incidence 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.