[Study on the association between compound hot extremes and fall death risk in three provinces of southern China]

Objective: To explore the risk fall death associated with compound hot extremes. Methods: This study collected data on fall deaths in Guangdong, Hunan, and Zhejiang Provinces from 2013 to 2018 and matched their exposure to meteorological data. Based on a time-stratified case-crossover design, a conditional logistic regression model embedded with a cross-basis function of the distributed lag nonlinear model was applied to estimate the risk of fall to death due to compound hot extremes. Results: Compared with regular days, compound hot extremes significantly increased the risk of death from falls (OR=1.19, 95%CI: 1.09-1.30), and women (OR=1.27, 95%CI: 1.11-1.45) and the elderly age 65 and above (OR=1.24, 95%CI: 1.12-1.39) were more sensitive to compound hot extremes. The maximum duration of compound hot extremes was 7 days, and the maximum intensity was 6.2 ℃, and the duration and intensity were proportional to the risk of death from falls. The risk of death from falls increased by 12% (OR=1.12, 95%CI: 1.06-1.18) each day, increasing in duration after linearization. The risk of death from falls increased by 16% (OR=1.16, 95%CI: 1.10-1.22) for each 1 ℃ increase in linearized intensity. Conclusion: Compound hot extremes increase the risk of death cases from falls.