Heatwave exposure and sarcopenia progression among middle-aged and older adults: the longitudinal evidence from CHARLS.

BACKGROUND

With global climate change, heatwaves are intensifying in frequency and duration, adversely affecting human health. How heatwaves (HW) exposure contribute to the decline in muscle strength and sarcopenia progression among middle-aged and older adults remains unclear.

METHODS

Utilizing data from the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2015, low muscle strength and sarcopenia were defined according to the Asian Working Group for Sarcopenia 2019 consensus. HW exposure were defined based on temperature thresholds and durations, quantified by event and day counts. HW exposure was measured over 12 months prior to sarcopenia assessments at baseline (2011) and follow-up (2015). A difference-in-differences (DiD) approach was applied to examine the association between HW exposure and changes in muscle strength and sarcopenia status.

RESULTS

This study included 3,554 middle-aged and older adults, with an average age of 58.7 years, and 47.0% were male. Based on a specific HW definition (HW12: 97.5 percentile, duration ≥ 4 days), DiD analysis showed that each additional HW day exposure was associated with a decrease in muscle strength of 0.097 kg (95%CI: -0.124, -0.069, p < 0.001, in model 3) and each additional HW event was associated with a decrease in muscle strength of 0.66 kg (95%CI: -0.933, -0.386, p < 0.001, in model 3); each additional HW day exposure was associated with a 2.1% risk of sarcopenia status deterioration (OR: 1.021, 95%CI: 1.01, 1.031, p < 0.001, in model 3) and each additional HW event was associated with an 18.7% risk of sarcopenia status deterioration (OR: 1.187, 95%CI: 1.07, 1.316, p = 0.001, in model 3). Subgroup analysis indicated that urban residents and individuals with higher levels of education were particularly susceptible to sarcopenia status deterioration related to HW exposure.

CONCLUSIONS

HW exposure increases the risk of Sarcopenia Progression among middle-aged and older adults.