Risk and attributable fraction estimation for the impact of exposure to compound drought and hot events on daily stroke admissions.

Background: The projection indicates that compound drought and hot events (CDHEs) will intensify, posing risks to cardiovascular health by potentially increasing stroke incidents. However, epidemiological evidence on this topic remains scarce. This study investigates the association between exposure to CDHEs and the risk of daily stroke admissions, specifically examining the effects on various stroke categories such as Subarachnoid Hemorrhage (SAH), Intracerebral Hemorrhage (ICH), Ischemic Stroke (IS), Transient Ischemic Attack (TIA), and other types of stroke.

Methods: Data on daily stroke admissions from 2010 to 2015 were obtained from the Urban Employee Basic Medical Insurance (UEBMI) and Urban Resident Basic Medical Insurance (URBMI) claims databases in Guangzhou, China. Hot events were identified as days when the daily mean temperature exceeded the 75th percentile during the warm season (May to October) over the study period. The Standardized Precipitation Evapotranspiration Index (SPEI) was utilized to identify drought conditions, with thresholds set at -1 and -1.5 for low-severity and high-severity drought events, respectively. Through a generalized additive model (GAM), we analyzed the cumulative effects of CDHE exposure on daily stroke admissions and calculated the Attributable Fraction (AF) related to CDHEs.

Results: The analysis included 179,963 stroke admission records. We observed a significant increase in stroke admission risks due to exposure to hot events coupled with high-severity drought conditions (RR = 1.18, 95%CI: 1.01-1.38), with IS being the most affected category (RR = 1.20, 95%CI: 1.03-1.40). The AF of total stroke admission attributed to hot events in conjunction with high-severity drought conditions was 24.40% (95%CI: 1.86%-50.20%).

Conclusion: The combination of hot events with high-severity drought conditions is likely linked to an increased risk of stroke and IS admissions, which providing new insights into the impact of temperature and climate-related hazards on cardiovascular health.