Heatwave exposure and respiratory sarcopenia incidence in a Chinese cohort

Heatwaves are increasingly frequent due to climate change, yet their association with respiratory sarcopenia remains underexplored. We aimed to examine the association between heatwave exposure and incident respiratory sarcopenia in a Chinese cohort, identify potentially susceptible subpopulations, and evaluate the robustness of the findings across alternative exposure definitions. In a prospective cohort study of Chinese adults from 2011 to 2015, heatwave exposure was assessed at the city level as the difference in heatwave frequency and days between 2011 and 2015 across 12 definitions (HW01-HW12). Participants free of respiratory sarcopenia at baseline were followed to identify incident cases. Logistic regression estimated odds ratios and 95% confidence intervals for the association between heatwave exposure and respiratory sarcopenia. Subgroup analyses were stratified by age, sex, BMI, geographic region, and chronic lung disease status, and sensitivity analyses evaluated the robustness of the results. Among 1984 participants, 15.7% developed respiratory sarcopenia by 2015. Greater heatwave frequency was associated with higher odds of respiratory sarcopenia in five definitions, and more heatwave days were associated with higher odds across eleven definitions. Associations appeared stronger among participants with BMI < 23 and those with chronic lung disease, while no clear effect modification was observed by age, sex, or region. Sensitivity analyses yielded broadly consistent results. Heatwave exposure was associated with higher odds of incident PEFR-based respiratory sarcopenia in Chinese adults, particularly among those with low BMI or chronic lung disease. These findings support further research on environmental heat exposure and respiratory muscle-related health, while limitations related to exposure misclassification, residual environmental confounding, and indirect outcome measurement should be considered.