Long-term exposure to air pollution, cause-specific mortality and incidence of stroke and acute coronary heart disease in the Rome Longitudinal Study: the BIGEPI project

Background and Aim Long-term air pollution exposure increases cause-specific mortality and incidence of cardiovascular diseases. Within the BIGEPI project, we aimed to investigate the association between long-term exposure to air pollutants, cause-specific mortality, incidence of coronary heart diseases and stroke in 6 large Italian administrative cohorts. We report preliminary results for Rome. Methods We enrolled 1,739,277 adults from the Rome Longitudinal Study at 2011 census, and followed them up until 2018. We analysed natural, cardiovascular and respiratory mortality, stroke and acute coronary heart disease (CHD) incidence. We assigned annual mean concentrations of particular matter <10 μm (PM₁₀), PM <2.5 μm (PM₂.₅), nitrogen dioxide (NO₂) and warm-season ozone (warm-O₃) at baseline residential addresses from satellite-based spatiotemporal models. We applied Cox proportional hazards models adjusted for individual and area-level covariates, in single- and two-exposure models. We investigated effect modification by age, sex, educational level, employment status and socioeconomic deprivation index. Results We observed 167,300 deaths from natural causes (62,368 cardiovascular, 12,286 respiratory), 42,241 CHD incident cases and 24,835 cases of incident stroke. PM₂.₅ was positively associated with natural, cardiovascular, respiratory mortality and stroke incidence: interquartile range (IQR) increases of 1.69 μg/m³ were associated with hazard ratios (HR) of 1.007 (95% confidence interval: 1.000-1.014), 1.018 (1.006-1.030), 1.028 (1.001-1.056) and 1.025 (1.007-1.044), respectively. We found positive associations between NO₂ and cardiovascular mortality (HR=1.021; 1.007-1.034 per IQR=11.53 μg/m³) and between warm-O₃ and CHD incidence (HR=1.024; 1.011-1.037 per 3.57 μg/m³). Associations tended to attenuate in two-exposure models. The effects were stronger for females and in the age group 30-64 years, with no major differences by individual or area-level socioeconomic indicators. Conclusions We estimated consistent associations between long-term air pollution exposure and cause-specific mortality and CVD incidence. Similar analyses will be conducted in other 5 administrative cohorts. Keywords: air pollution, cause-specific mortality, stroke, acute coronary heart disease.