The effect of muscle quality index on risk of adverse health outcomes: a prospective cohort study of 355,209 adults.

BACKGROUND

Muscle quality index (MQI), a new metric for assessing sarcopenia, reflects the functional capacity of muscle. However, the associations between MQI and adverse health outcomes and the corresponding mechanisms are not well understood.

OBJECTIVES

We aimed to prospectively evaluate the associations of MQI with risk of 9 adverse health outcomes [i.e., osteoarthritis, cardiovascular disease (CVD), type 2 diabetes mellitus (T2DM), respiratory disease, chronic kidney disease (CKD), liver disease, dementia, depression, and all-cause mortality], as well as the mediating role of metabolomics in these associations.

METHODS

This study included 355,209 adults from the UK Biobank. MQI was defined as the ratio of dominant hand grip strength to the corresponding arm fat-free mass and was subsequently categorized into sex-specific quintiles. The endpoints were 9 incident adverse health outcomes. Cox models were used to assess the associations. The mediating effect of the "metabolomic risk score" (MRS), derived from 249 plasma metabolites through Least Absolute Shrinkage and Selection Operator (LASSO) regression, was then assessed to understand its role in the above associations.

RESULTS

In the Cox analysis, compared with participants in MQI Q1, those in Q2-Q5 showed reduced risk of adverse health outcomes (all P for trend < 0.001). For instance, for participants in MQI Q5, the multivariable-adjusted hazard ratios were 0.57 [95% confidence interval (CI): 0.55, 0.58] for osteoarthritis, 0.70 (95% CI: 0.68, 0.73) for CVD, and 0.36 (95% CI: 0.34, 0.39) for T2DM, 0.72 (95% CI: 0.68, 0.76) for respiratory disease, 0.58 (95% CI: 0.54, 0.61) for CKD, 0.53 (95% CI: 0.49, 0.56) for liver disease, 0.69 (95% CI: 0.64, 0.76) for dementia, 0.53 (95% CI: 0.50, 0.57) for depression, and 0.69 (95% CI: 0.66, 0.72) for all-cause mortality (all P < 0.001). Mediation analysis showed MRS partially mediated these associations, with mediation proportions of 9.98%-42.86%.

CONCLUSIONS

Our findings highlight the importance of enhancing muscle quality to prevent chronic diseases and unveil underlying mechanisms.