The Influence of Different Solvents on Systemic Sclerosis: An Updated Meta-analysis of 14 Case-Control Studies.

Background Several studies have collected detailed data to examine which specific solvents account for the association between solvents and risk of systemic sclerosis (SSc). These studies generally reported elevated risks associated with many of the specific solvents examined, such as toluene, xylene, and trichloroethylene. The previous meta-analysis was not able to conduct separate analyses for specific solvent subtypes. Objective The aims of the new meta-analysis were to investigate a more comprehensive estimate and to consider the effect of different solvents on SSc. Methods We searched PubMed, Biosis Previews, China National Knowledge Infrastructure, and Wanfang for all articles published before July 2015. Fourteen case-control studies (1657 patients and 3838 controls) were included. The quality of studies was scored according to the Newcastle-Ottawa scale. The final odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by a fixed- or random-effects model according to heterogeneity test. Publication bias was assessed using Begg test. Results The risk of SSc was significantly different among sex, age, and exposure assessment methods. Separate analyses for specific solvent subtypes indicated that SSc was associated with aromatic solvents (OR, 2.72; 95% CI, 1.21-6.09), trichloroethylene (OR, 2.07; 95% CI, 1.34-3.17), halogenated solvents (OR, 1.49; 95% CI, 1.12-1.99), and ketones (OR, 4.20; 95% CI, 2.19-8.06). Conclusions Exposure to identified types solvents does seem to be a risk factor for developing SSc. Needed efforts to decrease such exposures are discussed.