Differential Susceptibility in Ambient Particle-Related First-Ever Stroke Onset Risk: Findings From a National Case-Crossover Study

Abstract

Different populations may respond differently to ambient fine particulate (PM_2.5) exposure; however, less is known about the distribution of susceptible individuals among the entire population. We conducted a time-stratified case-crossover design to assess associations between stroke risk and PM_2.5. During 2013–2015, 1,356 first-ever stroke onset events were derived from a large representative sample, the China National Stroke Screening Survey (CNSSS) database; daily PM_2.5 averages with a spatial resolution of 0.1° were estimated using a data assimilation approach combining satellite measurements, air model simulations and monitoring values. The distribution of susceptibility was derived according to individual-specific effects of PM_2.5 modified by different combinations of individual-level characteristics and their joint frequencies among all the CNSSS participants (n = 1,292,010). We found that the first-ever stroke onset was statistically significant associated with PM_2.5 (odds ratio = 1.049 (95% confidence interval: 1.038, 1.061) per 10-μg/m³). This association was modified by demographic (e.g., sex), lifestyle (e.g., overweight/obesity) and medical history variables (e.g., diabetes). The combined effects of PM_2.5 varied from 0.966 (0.920, 1.013) to 1.145 (1.080, 1.215) per 10-μg/m³ increment in different subpopulations. We found that most of the CNSSS participants were at increased risk of PM_2.5-related stroke, while only a small proportion were highly susceptible.