Effect of short-term exposure to air pollution on ischemic stroke incidence and mortality: a five-year time-series study in Jining, China.

BACKGROUND

Short-term exposure to air pollutants is associated with an increased risk of ischemic stroke incidence and mortality. However, there is a lack of research based on data from disease surveillance systems. This study used disease surveillance system data to quantitatively analyze the association between air pollution and ischemic stroke incidence and mortality in Jining, China.

METHODS

The stroke registration system of the Jining City Center for Disease Control and Prevention (CDC) includes information on confirmed stroke cases reported by all medical institutions in the jurisdiction, covering a population of 8.9 million. Generalized linear regression models combined with distributed lag nonlinear models (DLNM) were used to determine the association between air pollutants and ischemic stroke incidence and mortality. Stratified analyses by sex, age, and season were also conducted.

RESULTS

During the study period (January 1, 2018, to December 31, 2022), there were 209,949 ischemic stroke incidence cases and 23,565 ischemic stroke-related deaths. There were more ischemic stroke incidence and death cases in males compared to females. The number of incidence cases was higher in the warm season (52.6%) than in the cold season (47.4%), while this pattern was reversed for the number of deaths, with a higher number of deaths in the cold season (55.9%) than in the warm season (44.1%). This study showed that exposure to particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), and carbon monoxide (CO) was associated with ischemic stroke incidence, and exposure to PM2.5, PM10, sulfur dioxide (SO2), and CO was associated with ischemic stroke mortality. The relative risks (RRs, with 95% CIs) for ischemic stroke incidence at the maximum single-lag effect day for each interquartile range (IQR) increment for PM2.5, PM10, NO2, and CO were 1.007 (1.001-1.014), 1.004 (1.000-1.008); 1.031 (1.011-1.051), and 1.008 (1.001-1.015), respectively. The RRs (with 95% CIs) for mortality for PM2.5, PM10, SO2, and CO were 1.049 (1.025-1.073), 1.031 (1.014-1.048), 1.021 (1.001-1.041), and 1.044 (1.017-1.071), respectively. Furthermore, the association between air pollution and ischemic stroke incidence risk was modified by age and season. Individuals aged >75 years were more vulnerable to SO2-induced ischemic stroke incidence risk, and PM2.5 and CO were more harmful in the cold season.

CONCLUSION

These findings suggest that short-term exposure to PM2.5, PM10, SO2, NO2, and CO leads to increased ischemic stroke morbidity and mortality. The elderly population, as well as the general population, should be better protected during the cold season.