Objective  To investigate the potential association between multimorbidity and the handgrip strength of middle-aged and older adults.

  Methods  The baseline (2011) and second-round follow-up (2015) data of China Health and Retirement Longitudinal Study (CHARLS) were used. Adults≥40 were selected as the subjects of the study. Variables incorporated in the study included handgrip strength, chronic disease prevalence, demographic variables, and health behavior variables. Generalized estimating equations were used to analyze the longitudinal association between handgrip strength and multimorbidity.

  Results  A total of 28 368 middle-aged and older adults were included in the baseline and follow-up samples, with an average age of (59.1±9.7) years old, the oldest being 96 while the youngest being 40. Among them, 6 239 were male, accounting for 47.3%. In the second-round follow-up, 9 186 baseline respondents and 5 994 new respondents were covered, reaching a total of 15 180 respondents. Compared with the baseline, a higher proportion of the second-round follow-up respondents were female (P=0.033) and were older (P<0.001). From the baseline to the second-round follow-up, Q1, the lowest grip strength category, increased from 23.4% to 26.6%, while Q4, the highest grip strength category, decreased from 26.5% to 21.2%. The prevalence of having more than three chronic diseases increased from 18.2% to 24.2% and the prevalence of having more than five chronic diseases increased from 3.3% to 6.2%. After adjusting for confounding variables, the interaction items of handgrip strength and time showed statistical significance. After stratification by gender, the interaction items of male handgrip strength and follow-up time were statistically significant in both models (P<0.05). The marginal effect graph of the interactive item showed that the multimorbidity prevalence of respondents with lower handgrip levels grew faster with age. Individual effect analysis showed that the correlation between handgrip strength and multimorbidity was not statistically significant at baseline, but the follow-up done four years afterwards showed statistical significant correlation between handgrip strength and multimorbidity.

  Conclusion  Respondents with lower baseline handgrip strength are associated with increasingly higher risk of multimorbidity over time. Handgrip strength can be used as an effective screening tool for middle-aged and older adults in China to identify those at higher risks of multimorbidity of chronic diseases.