Grip strength indicators and successful aging among middle-aged and older adults: evidence from the CHARLS cohort.

Successful aging is a multidimensional core concept encompassing physical, psychological, and social adaptability. Its non-achievement not only significantly reduces the quality of life of older adults but also increases the care and economic burden on families and society. This study aimed to systematically explore the association between multidimensional grip strength indicators and successful aging among middle-aged and older adults in China, and to clarify the strength of association of different indicators. Using prospective cohort data from four waves (2011-2018) of the China Health and Retirement Longitudinal Study (CHARLS), successful aging was defined based on the internationally accepted five-dimensional Rowe-Kahn criteria. Multivariate logistic regression models and Latent Class Growth Model (LCGM) were used to analyze the associations of successful aging with baseline grip strength, three-time average grip strength, longitudinal grip strength variability indicators, and long-term grip strength trajectories, respectively. Results showed that among 1,892 participants, 52 (2.76%) achieved successful aging during follow-up. Three-time average grip strength was significantly and robustly positively associated with successful aging - after full covariate adjustment, each 1-unit increase was associated with a 7.8% higher probability of achieving successful aging (OR = 1.078, 95% CI: 1.023-1.137, P = 0.005), and its model discriminative power was significantly superior to single baseline grip strength measurement. Variability Independent of the Mean (VIM) was significantly negatively associated with successful aging - after full covariate adjustment, each 1-unit increase was associated with a 35.2% lower probability of achieving successful aging (OR = 0.648, 95% CI: 0.417-0.962, P = 0.042). Additionally, compared with the high-baseline slight decline trajectory, middle-aged and older adults with the moderate-baseline gentle decline trajectory had a 61% significantly lower probability of achieving successful aging (OR = 0.390, 95% CI: 0.161-0.944, P = 0.035). These findings indicate that multidimensional grip strength indicators are significantly associated with successful aging among middle-aged and older adults in China, with three-time average grip strength and VIM showing the strongest associations. The results can provide evidence-based reference for health risk stratification in older adults.