[Study on the effect and burden of precipitation on road traffic injuries in Zhejiang Province]

Objective: To analyze the effect of precipitation on road traffic injuries (RTI) in Zhejiang Province. Methods: The RTI surveillance and meteorological data from 2009 to 2022 in Zhejiang Province were collected. Based on the time-stratified case-crossover design, the precipitation of case day and control day was compared, and the distributed lag nonlinear model was applied to analyze the correlation of precipitation and RTI. Stratified analyses were conducted to analyze the effect modification of gender, age, injury location, and temperature. An attributable fraction was used to assess the burden of RTI caused by precipitation. Results: A total of 239 970 RTIs were monitored in Zhejiang Province from 2009 to 2022, averaging 46 daily cases. The distributed lag nonlinear model showed that compared with no rain, the risk of RTI increased first and then decreased with the increase of precipitation. The risk of RTI was the highest when the precipitation was 30.99 mm (OR=1.08, 95%CI: 1.05-1.11). The adverse effects on RTI mainly occurred on the day of precipitation, and it showed insignificant or protective effects with the extension of lag days. 1.34%(95%CI: 1.31%-1.36%) of RTI could be attributed to precipitation. Stratified analysis showed that gender, age, injury location, and temperature may modify the effect of precipitation on RTI. Precipitation caused a heavier burden on RTI in subgroups aged 18-64, females, and occurring on roads and in low temperatures. Conclusions: Precipitation can increase the risk of RTI. People aged 18-64 or females are the key groups for RTI prevention, and prevention and control efforts of precipitation-related RTI should be increased in road and low-temperature environments.