Contribution of low skeletal muscle mass in predicting cardiovascular events: A prospective cohort study

Background: We aimed to explore the association between skeletal muscle mass and cardiovascular events, and its additional value on the assessment of cardiovascular diseases (CVD) over traditional risk scores. Methods: The study included 1365 community-based participants aged over 50 years and free of CVDs at base-line. Participants completed detailed assessments at baseline and received a follow-up assessment in 2021-2022 via phone calls or electronic medical records. Skeletal muscle mass was measured using an automatic bioelectric analyzer. Predicted probabilities of 10-year atherosclerotic cardiovascular disease (ASCVD) risk were estimated individually with the China-PAR equation. Results: After a mean follow-up of 7.6 years, 144 cardiovascular events were identified. The fully-adjusted hazard ratios (HRs) of cardiovascular events were 0.93 (0.88-0.98) and 1.08 (1.04-1.12) for skeletal muscle mass and predicted 10-year risk, respectively. Among participants over 60 years and with two or more risk factors, car-diovascular events risk increased progressively with each decreasing skeletal muscle tertile. Receiver operating characteristic curves showed that the C-statistic of predicting cardiovascular events for a 10-year risk assessment was slightly increased after adding skeletal muscle mass. The categorical net reclassification improvement (NRI) showed a 56.7% increase in the reclassification. The continuous NRI and integrated discrimination improvement increased as well. Conclusion: Participants with low skeletal muscle mass were more likely to have cardiovascular events. Low muscle mass improved the predictive power of CVD incidence over the original risk score, indicating that muscle mass could be a valuable parameter and a declining value needed early detection in the population.