Short-term environmental triggers of hemorrhagic stroke

Hemorrhagic stroke (HS) is associated with severe morbidity and high mortality. Identifying the trigger factors for HS is critical for disease prevention. This study aimed to assess the associations between short-term environmental triggers (STETs) and HS risk. We systematically searched six databases for articles published up to September 9, 2022. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using random-effect models to evaluate the associations between STETs and the risk of HS. Heterogeneity was assessed using Cochran Q and I² tests. A total of 63 studies were included for analysis. Of these, 40 focused on air pollutants and 23 on meteorological factors. Pooling results showed that exposure to particulate matter 2.5 (PM_2.5; OR, 1.003 per 10 μg/m³; 95% CI, 1.001-1.007), sulfur dioxide (SO_2; OR, 1.022 per 10 ppb; 95% CI, 1.005-1.040), and nitrogen dioxide (NO_2; OR, 1.026 per 10 ppb; 95% CI, 1.004-1.047) was associated with an increase in HS risk. Moreover, exposure to PM_2.5 (OR, 1.018 per 10 μg/m³; 95% CI, 1.009-1.027) and SO₂ (OR, 1.102 per 10 ppb; 95% CI, 1.010-1.204) was positively associated with the risk of intracerebral hemorrhage. In addition, extreme temperature, high pressures, high and low relative humidity were potentially associated with HS risk. Targeted preventive measures to limit the effect of these air pollutants and extreme meteorological factors should be taken to reduce the HS disease burden. Further studies are warranted to verify these findings.