Associations of outdoor fine particulate air pollution and cardiovascular disease in 157 436 individuals from 21 high-income, middle-income, and low-income countries (PURE): a prospective cohort study

Abstract

Background Most studies of long-term exposure to outdoor fine particulate matter (PM5) and cardiovascular disease are from high-income countries with relatively low PM25 concentrations. It is unclear whether risks are similar in low-income and middle-income countries (LMICs) and how outdoor PM contributes to the global burden of cardiovascular disease. In our analysis of the Prospective Urban and Rural Epidemiology (PURE) study, we aimed to investigate the association between long-term exposure to come, middle-income, and low-income countries. Methods In this multinational, prospective cohort study, we studied 157 436 adults aged 35-70 years who were enrolled in the PURE study in countries with ambient PM25 estimates, for whom follow-up data were available. Cox proportional hazard frailty models were used to estimate the associations between long-term mean community outdoor PM concentrations and cardiovascular disease events ( fatal and non-fatal), cardiovascular disease mortality, and other non-accidental mortality. Findings Between Jan 1, 2003, and July 14, 2018, 157 436 adults from 747 communities in 21 high-income, middle-income, and low-income countries were enrolled and followed up, of whom 140 020 participants resided in LMICs. During a median follow-up period of 9 center dot 3 years (IQR 7 center dot 8-10 center dot 8; corresponding to 1 center dot 4 million person-years), we documented 9996 non-accidental deaths, of which 3219 were attributed to cardiovascular disease. 9152 (5 center dot 8) of 157 436 participants had cardiovascular disease events (fatal and non-fatal incident cardiovascular disease), including 4083 myocardial infarctions and 4139 strokes. Mean 3-year PM25 at cohort baseline was 47 center dot 5 mu g/m(3) (range 6-140). In models adjusted for individual, household, and geographical factors, a 10 mu g/m(3) increase in PM25 was associated with increased risk for cardiovascular disease events (hazard ratio 1 center dot 05 95% CI 1 center dot 03-1 center dot 07), myocardial infarction (1 center dot 03 1 center dot 00-1 center dot 05), stroke (1 center dot 07 1 center dot 04-1 center dot 10), and cardiovascular disease mortality (1 center dot 03 1 center dot 00-1 center dot 05). Results were similar for LMICs and communities with high PM25 concentrations (>35 mu g/m(3)). The population attributable fraction for PM25 in the PURE cohort was 13 center dot 9% (95% CI 8 center dot 8-18 center dot 6) for cardiovascular disease events, 8 center dot 4% (0 center dot 0-15 center dot 4) for myocardial infarction, 19 center dot 6% (13 center dot 0-25 center dot 8) for stroke, and 8 center dot 3% (0 center dot 0-15 center dot 2) for cardiovascular disease mortality. We identified no consistent associations between PM25 and risk for non-cardiovascular disease deaths. Interpretation Long-term outdoor PM25 concentrations were associated with increased risks of cardiovascular disease in adults aged 35-70 years. Air pollution is an important global risk factor for cardiovascular disease and a need exists to reduce air pollution concentrations, especially in LMICs, where air pollution levels are highest. Copyright (c) 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND 4.0 license.