Association of Exposure to Particular Matter and Carotid Intima-Media Thickness: A Systematic Review and Meta-Analysis

BACKGROUND: Long time exposure to particular matter has been linked to myocardial infarction, stroke and blood pressure, but its association with atherosclerosis is not clear. This meta-analysis was aimed at assessing whether PM₂.₅ and PM₁₀ have an effect on subclinical atherosclerosis measured by carotid intima-media thickness (CIMT). METHODS: Pubmed, Ovid Medline, Embase and NICK between 1948 and 31 March 2015 were searched by combining the keywords about exposure to the outcome related words. The random-effects model was applied in computing the change of CIMT and their corresponding 95% confidence interval (95% CI). The effect of potential confounding factors was assessed by stratified analysis and the impact of traffic proximity was also estimated. RESULTS: Among 56 identified studies, 11 articles satisfied the inclusion criteria. In overall analysis increments of 10 μg/m³ in PM₂.₅ and PM₁₀ were associated with an increase of CIMT (16.79 μm; 95% CI, 4.95-28.63 μm and 4.13 μm; 95% CI, -5.79-14.04 μm, respectively). RESULTS shown in subgroup analysis had reference value for comparing with those of the overall analysis. The impact of traffic proximity on CIMT was uncertain. CONCLUSIONS: Exposure to PM₂.₅ had a significant association with CIMT and for women the effect may be more obvious.