Associations of muscle mass, strength, and quality with all-cause mortality in China: a population-based cohort study

Abstract

Background: It remains unclear about the association of muscle mass, strength, and quality with death in the general Chinese population of diverse economical and geographical backgrounds. The present study aimed to comprehensively examine such associations across different regions in China.

Methods: Based on the China Kadoorie Biobank study, the present study included 23,290 participants who were aged 38 to 88 years and had no prevalent cardiovascular diseases or cancer. Muscle mass and grip strength were measured using calibrated instruments. Arm muscle quality was defined as the ratio of grip strength to arm muscle mass. Low muscle mass, grip strength, and arm muscle quality were defined as the sex-specific lowest quintiles of muscle mass index, grip strength, and arm muscle quality, respectively. Cox proportional hazards models yielded hazard ratios (HRs) and 95% confidence intervals (CIs) for risks of all-cause mortality in relation to muscle mass, strength, and quality.

Results: During a median follow-up of 3.98 years, 739 participants died. The HR (95% CI) of all-cause mortality risk was 1.28 (1.08-1.51) for low appendicular muscle mass index, 1.38 (1.16-1.62) for low total muscle mass index, 1.68 (1.41-2.00) for low grip strength, and 1.41 (1.20-1.66) for low arm muscle quality in models adjusted for sociodemographic characteristics, lifestyle factors, and medical histories.

Conclusion: Low muscle mass, grip strength, and arm muscle quality are all associated with short-term increased risks of mortality, indicating the importance of maintaining normal muscle mass, strength, and quality for general Chinese adults.

Figure 1

Restricted cubic splines for associations between muscle mass indices and all-cause mortality. The four knots for restricted cubic splines were set at the 5th, 35th, 65th, and 95th percentages of muscle mass indices, and the median values of muscle mass indices were the reference points. Solid lines represent HRs and dashed lines represent 95% CIs. Likelihood ratio tests were used to test for non-linearity (appendicular muscle mass index: P = 0.103; total muscle mass index: P = 0.107; arm muscle mass index: P = 0.071; leg muscle mass index: P = 0.126; trunk muscle mass index: P = 0.009). Models were adjusted for variables in model 3 of Table 2. CIs: Confidence intervals; HRs: Hazard ratios.