ABSTRACT NUMBER: ESOC2026A615 AMBIENT TEMPERATURE AND STROKE SUBTYPE: ISCHAEMIC VS HAEMORRHAGIC STROKE

Abstract Background and aims Ambient temperature has been linked to stroke incidence, but its relationship with stroke subtype remains unclear. We examined the association between short-term ambient temperature exposure and stroke subtype, comparing ischaemic stroke with intracerebral haemorrhage. Methods We retrospectively analysed 1,198 patients with radiologically confirmed stroke and documented symptom onset over four years. Daily mean ambient temperatures were obtained from high-resolution meteorological data. A lagged exposure window was defined from the day of symptom onset (day 0) to the preceding three days (days −1 to −3). The primary exposure was the mean temperature across these four days (Mean 0-3). Unadjusted associations between temperature quartiles and stroke subtype were assessed using cross-tabulation. Multivariable binary logistic regression was used to estimate the association between mean temperature (per 1°C increase) and stroke subtype, adjusting for age, sex, and baseline National Institutes of Health Stroke Scale score. Results Haemorrhagic stroke constituted a higher proportion of cases in the lowest temperature quartile compared with the highest quartile (26% vs 19%; p = 0.040). In adjusted analyses, higher ambient temperatures were associated with lower odds of haemorrhagic stroke. Each 1°C increase in mean temperature was associated with a 4.3% reduction in the odds of haemorrhagic versus ischaemic stroke (adjusted OR 0.957, 95% CI 0.938-0.977; p < 0.001). Conclusions Short-term ambient temperature exposure was independently associated with stroke subtype. Lower temperatures were linked to a higher relative proportion of haemorrhagic stroke, whereas higher temperatures favoured ischaemic events, suggesting that ambient thermal conditions may influence stroke phenotype. Conflict of interest Ahmed Abdalla: nothing to disclose, Nermin Hamdy: nothing to disclose,