Two-wave status patterns of handgrip strength asymmetry and low handgrip strength in relation to all-cause mortality in middle-aged and older Chinese adults.

Handgrip strength asymmetry (HGSA) and low handgrip strength (LHGS) reflect distinct aspects of muscle health, but their changes over time have been less studied. We examined whether two-wave status patterns of HGSA and LHGS were associated with all-cause mortality in middle-aged and older Chinese adults. We analyzed 8924 participants aged ≥ 45 years from the China Health and Retirement Longitudinal Study. HGSA and LHGS were assessed in 2011 and 2013 and classified as normal at both waves, newly abnormal at Wave 2, normalized at Wave 2, or abnormal at both waves. The 2013 assessment served as the landmark baseline, and mortality follow-up continued through 2018. Cox models estimated hazard ratios (HRs) and 95% confidence intervals (CIs). During a median follow-up of 5.38 years, 647 deaths occurred. For HGSA, only abnormal status at both waves was associated with higher mortality (HR 1.32, 95% CI 1.07-1.61). For LHGS, newly abnormal status at Wave 2 (HR 1.91, 95% CI 1.54-2.37), normalized status at Wave 2 (HR 1.54, 95% CI 1.21-1.97), and abnormal status at both waves (HR 2.35, 95% CI 1.88-2.94) were each associated with higher mortality. Participants with both HGSA and LHGS at Wave 2 also had higher mortality (HR 2.30, 95% CI 1.84-2.87). Increasing asymmetry and loss of relative grip strength were also associated with mortality. Two-wave status patterns of HGSA and LHGS showed distinct mortality associations, with more consistent associations for LHGS. Assessing bilateral imbalance together with absolute weakness may help characterize muscle-health risk in aging populations.