Abstract Number: Esoc2026a65 Differential Effects of Temperature on Ischemic, Hemorrhagic, and Subarachnoid Hemorrhage Stroke Mortality in Brazil

Background and aims Stroke subtypes exhibit pathophysiological mechanisms that may confer differential vulnerability to environmental stressors. While temperature associations with overall stroke incidence are well-established in temperate regions, evidence from tropical-subtropical settings remains scarce. We investigated whether ischemic stroke (IS), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH) demonstrate heterogeneous temperature-mortality relationships in Brazil. Methods We conducted a time-series analysis linking monthly nationwide stroke mortality data (ICD-10: I60, I61-I62, I63) from Brazil's Unified Health System with meteorological data from the National Institute of Meteorology (2020-2024). Pearson correlations between minimum temperature (TMIN) and subtype-specific mortality were stratified by season (Southern Hemisphere). Mann-Whitney U tests compared winter versus summer mortality rates. Results 1,720 stroke deaths (194 IS, 975 ICH, 551 SAH), overall temperature-mortality correlations differed by subtype: SAH (r=-0.255, p=0.049), IS (r=-0.164, p=0.209), and ICH (r=+0.101, p=0.444). Seasonal stratification revealed heterogeneity: IS demonstrated strong inverse correlation during winter (r=-0.663, p=0.007); ICH showed inverse correlation during spring (r=-0.584, p=0.022); SAH exhibited consistent inverse trends across autumn (r=-0.437) and winter (r=-0.395), though not reaching statistical significance. Winter-to-summer mortality comparisons showed opposing patterns: SAH increased 12.5% (8.5→9.6 deaths/month), IS increased 5.7%, while ICH decreased 5.0% during colder months. Conclusions Stroke subtypes demonstrate divergent temperature-mortality associations in tropical-subtropical Brazil, with SAH and IS showing cold-season vulnerability while ICH exhibits paradoxical warm-season peaks. These findings suggest subtype-specific physiological responses to thermal stress and the importance of disaggregated analyses in climate-stroke research for tailored prevention strategies in climatically diverse regions. Conflict of interest None of the authors: nothing to disclose Figure 1 - belongs to Results