Short-term effect of PM2.5 on stroke in susceptible populations: A case-crossover study

Abstract

Background: Fine particulate matter (PM2.5) is a risk factor for stroke, and patients with pre-existing diseases appear to be particularly susceptible. We conducted a case-crossover study to examine the association between short-term exposure to fine particulate matter (PM2.5) and hospital admission for stroke in individuals with atrial fibrillation (AF), hypertension, diabetes, or hyperlipidemia. Methods: Patients diagnosed with acute ischemic stroke (AIS) were recruited from 2015 to 2017 in Chinese Stroke Center Alliances. We estimated daily PM2.5 average exposures with a spatial resolution of 0.1° using a data assimilation approach combining satellite measurements, air model simulations, and monitoring values. Conditional logistic regression was used to assess PM2.5-related stroke risk in patients with pre-existing medical co-morbidities. Results: A total of 155,616 patients diagnosed with AIS were admitted. Patients with a history of AF ( n = 15,430), hypertension ( n = 138,220), diabetes ( n = 43,737), or hyperlipidemia ( n = 16,855) were assessed separately. A 10 µg/m3 increase in daily PM2.5 was associated with a significant increase in AIS for individuals with AF at lag 4 (odds ratio (OR), 1.008; 95% confidence interval (CI), 1.002–1.014), and with hypertension (OR, 1.008; 95% CI, 1.006–1.010), diabetes (OR, 1.006; 95% CI, 1.003–1.010), and hyperlipidemia (OR, 1.007; 95% CI, 1.001–1.012) at lags 0–7. Elderly (⩾ 65 years old) and female patients with AF had significantly higher associations at lag 5 (OR, 1.009; 95% CI, 1.002–1.015) and lag 5 (OR, 1.010; 95% CI, 1.002–1.018), respectively. Conclusion: Short-term exposure to PM2.5 is significantly associated with hospital admission for stroke in individuals with pre-existing medical histories, especially in older or female patients with AF. Preventive measures to reduce PM2.5 concentrations are particularly important in individuals with other medical co-morbidities.