Methods: Cardiovascular risk factor data were obtained from the SUrvey of Risk Factors (SURF) for coronary heart disease (CHD) patients. Annual average PM2.5 concentrations were estimated using recent global WHO PM2.5 maps combining satellite and surface monitoring data for the location of the 71 participating centers. Associations of PM2.5 with risk factors were assessed by mixed-effect generalized estimation equation models adjusted by sex, age, exercise, and smoking. We assessed whether additional adjustment for country affected associations.
Results: 8392 patients (30% women) were included. Globally, an increase of 10 µg/m3 in PM2.5 was significantly associated with decreased BP and increased glucose. No associations were found with lipids. After controlling for country, an increase of 10 µg/m3 in PM2.5 was associated with decreased BP and increased LDL (SBP: -0.45mmHg, 95% CI: -0.85, -0.06;DBP: -0.47mmHg, 95% CI: -0.73, -0.20;LDL: 0.04mmol/L, 95%CI: 0.01, 0.08). The association with glucose attenuated (0.08mmol/L, 95% CI: -0.23, 0.16).
Conclusion: Global associations of PM2.5 and cardiovascular risk factors can be determined linking risk factor and geospatial air pollution data but the sensitivity of effect estimates to adjustment for country stress the need for multiple centers per country. After country adjustment, PM2.5 was associated with small increases in LDL and small decreases in BP.