Occupational silica exposure as a risk factor for scleroderma: a meta-analysis

Abstract

Objectives: Among potential environmental risk factors for systemic sclerosis (SSc), occupational exposures have received some attention. In this meta-analysis, we examined the association between SSc and occupational exposure to silica.

Methods: We searched Medline, Toxline, BIOSIS, and Embase (1949 and November 2009) for original articles published in any language. Sixteen studies are included in the analysis, of which, 3 are cohort studies, 9 case-control and 4 are of other designs. The combined estimator of relative risk (CERR) and 95% confidence interval (CI) were calculated using fixed or random effect models.

Results: Significant heterogeneity was detected (I (2) = 97.2%; P < 0.01), and the CERR was 3.20 (95% CI, 1.89-5.43). The CERR for studies in females was 1.03 (95% CI, 0.74-1.44) and was 3.02 (95% CI, 1.24-7.35) for males. The CERR for case-control studies was 2.24 (95% CI, 1.65-3.31) and was 15.49 (95% CI, 4.54-52.87) for cohort studies.

Conclusions: The findings suggest that silica exposure may be a significant risk factor for developing SSc and specifically in males. Further observational studies examining the role of occupational silica exposure in the context of other risk factors are needed.