Post-Discharge Ambient Sulfur Dioxide Exposure and Stroke Recurrence After Acute Ischemic Stroke

초록

Background and Purpose Ambient air pollution is an established risk factor for incident stroke, but whether post-discharge pollutant exposure influences stroke recurrence remains unclear. We investigated the association between post-discharge exposure to six ambient air pollutants and stroke recurrence after acute ischemic stroke. Methods We analyzed 27,340 patients in the Clinical Research Collaboration for Stroke in Korea– National Institutes of Health nationwide multicenter registry (2014–2021). The 3-month post-discharge district-level mean concentrations of particulate matter ≤10 μm (PM10), ≤2.5 μm (PM2.5), nitrogen dioxide, sulfur dioxide (SO2), carbon monoxide, and ozone were estimated by inversedistance-weighted interpolation. The primary outcome was stroke recurrence from 3 to 15 months post-discharge. Cause-specific Cox models with cluster-robust standard errors were used, treating death as a competing risk; non-linear dose-response was assessed by restricted cubic splines. Results During follow-up (median 364.8 days), 764 patients had recurrence and 542 died. Only SO2 showed a significant association with recurrence (P for overall association in the spline model=0.024), with a graded dose-response; the non-linear (J-shaped) pattern did not reach significance (P for non-linearity=0.095), and quartile contrasts were individually non-significant (Q4 vs. Q1: hazard ratio 1.19, 95% confidence interval 0.94–1.50). The association was numerically stronger among older adults (≥75 years; P for interaction=0.051) and women (P for interaction=0.062). The highest SO2 concentrations were observed in harbor cities (Incheon, Ulsan, Busan). No significant associations were observed for the other five pollutants. Conclusions Elevated post-discharge SO2 exposure was associated with increased stroke recurrence, with a graded dose-response, supporting consideration of ambient air quality in secondary stroke prevention. © 2026 Korean Stroke Society an Open Access.

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