Mesothelioma among Motor Vehicle Mechanics: An Updated Review and Meta-analysis

Background: We published a meta-analysis of the association between work as a motor vehicle mechanic and mesothelioma in 2004. Since then, several relevant studies on this topic have been published. Thus, to update the state-of-the-science on this issue, we conducted a new systematic review and meta-analysis. Methods: A comprehensive PubMed literature search through May 2014 was conducted to identify studies that reported relative risk estimates for mesothelioma among motor vehicle mechanics (in general), and those who were engaged in brake repair (specifically). Studies were scored and classified based on study characteristics. Random-effects meta-analyses generated summary relative risk estimates (SRREs) and corresponding 95% confidence intervals (CI). Heterogeneity of results was examined by calculating Q-test P-values (P-H) and I ² estimates. Sub-group and sensitivity analyses were conducted for relevant study characteristics and quality measures. Results: Ten case-control studies, one cohort study, and five proportionate mortality ratio (PMR)/standardized mortality odds ratio (SMOR) studies were identified and included in the quantitative assessment. Most meta-analysis models produced SRREs below 1.0, and no statistically significant increases in mesothelioma were observed. The SRRE for all studies was 0.80 (95% CI: 0.61-1.05) with significant heterogeneity (P-H <0.001, I ² = 62.90). A similar SRRE was observed among the five Tier 1 studies with the highest quality ratings (SRRE = 0.76, 95% CI: 0.46-1.25), with no heterogeneity among studies (P-H = 0.912, I ² = 0.00). Meta-analysis of the Tier 2 (n = 5) and Tier 3 (n = 6) studies resulted in SRREs of 1.09 (95% CI: 0.76-1.58) and 0.73 (95% CI: 0.49-1.08), respectively. Restricting the analysis to Tiers 1 and 2 combined resulted in an SRRE of 0.92 (95% CI: 0.72-1.29). The SRRE specific to brake work (n = 4) was 0.64 (95% CI: 0.38-1.09). Conclusions: This meta-analysis of the epidemiologic studies provides evidence that motor vehicle mechanics, including workers who were engaged in brake repair, are not at an increased risk of mesothelioma.