Long-Term Exposure to Traffic-Related Air Pollution and Stroke: A Systematic Review and Meta-Analysis

Background: Stroke remains the second cause of death worldwide. The mechanisms underlying the adverse association of exposure to traffic-related air pollution (TRAP) with overall cardiovascular disease may also apply to stroke. Our objective was to systematically evaluate the epidemiological evidence regarding the associations of long-term exposure to TRAP with stroke.

Methods: PubMed and LUDOK electronic databases were searched systematically for observational epidemiological studies from 1980 through 2019 on long-term exposure to TRAP and stroke with an update in January 2022. TRAP was defined according to a comprehensive protocol based on pollutant and exposure assessment methods or proximity metrics. Study selection, data extraction, risk of bias (RoB) and confidence assessments were conducted according to standardized protocols. We performed meta-analyses using random effects models; sensitivity analyses were assessed by geographic area, RoB, fatality, traffic specificity and new studies.

Results: Nineteen studies were included. The meta-analytic relative risks (and 95% confidence intervals) were: 1.03 (0.98-1.09) per 1 µg/m3 EC, 1.09 (0.96-1.23) per 10 µg/m3 PM10, 1.08 (0.89-1.32) per 5 µg/m3 PM2.5, 0.98 (0.92; 1.05) per 10 µg/m3 NO2 and 0.99 (0.94; 1.04) per 20 µg/m3 NOx with little to moderate heterogeneity based on 6, 5, 4, 7 and 8 studies, respectively. The confidence assessments regarding the quality of the body of evidence and separately regarding the presence of an association of TRAP with stroke considering all available evidence were rated low and moderate, respectively.

Conclusion: The available literature provides low to moderate evidence for an association of TRAP with stroke.

Note:

Funding Information: Research described in this article was conducted under contract to the HEI, an organization jointly funded by the United States Environmental Protection Agency (EPA) (Assistance Award No. CR-83998101) and certain motor vehicle and engine manufacturers.

Declaration of Interests: No author declares a conflict of interests.

Keywords: stroke, traffic related air pollution, long-term exposure, confidence assessment, systematic review, meta-analysis

Suggested Citation: Suggested Citation

Haddad, Pascale and Kutlar Joss, Meltem and Weuve, Jennifer and Vienneau, Danielle and Atkinson, Richard W. and Brook, Jeffrey R. and Chang, Howard H. and Forastiere, Francesco and Hoek, Gerard and Kappeler, Ron and Lurmann, Fred and Sagiv, Sharon and Samoli, Evangelina and Smargiassi, Audrey and Szpiro, Adam and Patton, Allison and Boogaard, Johanna and Hoffmann, Barbara, Long-Term Exposure to Traffic-Related Air Pollution and Stroke: A Systematic Review and Meta-Analysis. Available at SSRN: https://ssrn.com/abstract=4231952 or http://dx.doi.org/10.2139/ssrn.4231952