Neurology. 2026 May 12;106(9):e214879. doi: 10.1212/WNL.0000000000214879. Epub 2026 Apr 10.
ABSTRACT
BACKGROUND AND OBJECTIVES: Ambient particulate matter <2.5 μm (PM2.5) has been extensively associated with morbidity and mortality of stroke. However, most previous findings were derived from separate clinical phase analyses and have not focused on the specific components of PM2.5. Using a national cohort study based on multistate analysis, we aimed to evaluate the associations of PM2.5 and its specific components with several different clinical progression phases of stroke.
METHODS: We analyzed data from first-ever stroke patients in the Third China National Stroke Registry, and follow-up was conducted through March 2023. Ambient PM2.5 and its components were assessed using one-year average concentrations before the end point or the latest follow-up, obtained from Tracking Air Pollution in China. Outcomes were verified through hospital records and official registries. We used multistate models to estimate the associations and applied P-splines to assess potential nonlinear associations of PM2.5 and its components. We also conducted subgroup analyses to explore potential effect modification.
RESULTS: We included a total of 11,491 participants with a mean age of 61.5 ± 11.5 years, of whom 7,821 (68.1%) were male. We observed positive associations of PM2.5 mass concentrations and all 5 chemical components with each stage of ischemic stroke progression. For PM2.5 mass concentration, the adjusted hazard ratios per 12.5 μg/m3 increase were as follows: 2.82 (95% CI 2.69-2.94) for the transition from first stroke to recurrence, 2.85 (95% CI 2.40-3.37) from first stroke to poststroke cardiovascular diseases (PCVDs), 2.50 (95% CI 2.28-2.73) from first stroke to death, 2.23 (95% CI 1.97-2.53) from stroke recurrence to death, and 1.93 (95% CI 1.33-2.80) from PCVDs to death. All 5 chemical components also showed strong associations across each transition stage. The exposure-response relationships followed J-shaped curves (p for nonlinearity <0.001). Of interest, patients with good functional outcomes (modified Rankin Scale score ≤3) or mild strokes (NIH Stroke Scale score <5) had a higher risk of recurrence or death, possibly because of increased exposure to outdoor air pollution.
DISCUSSION: Long-term exposure to PM2.5 and its specific components was positively associated with the risk of recurrent stroke, and secondary morbidity and mortality. Exposure assessment relied on residential addresses rather than personal measurements, which should be noted as a limitation.
PMID:41962117 | DOI:10.1212/WNL.0000000000214879