Association Between Organic Dust Exposure and Adult-Asthma: A Systematic Review and Meta-Analysis of Case-Control Studies.

Background: Exposure to organic dust has been widely investigated as a potential risk factor for asthma with different results. To clarify a potential relationship, we performed the present meta-analysis to integrate the results of studies examining the association of organic dust exposure with asthma. Methods: A comprehensive literature search in the electronic databases including EMBASE, PubMed and Cochrane Library databases (up to August 2018) was conducted. The adjusted odds ratios (ORs) with corresponding 95% confidence interval (CI) for organic dust exposure and asthma were retrieved and pooled to generate summary effect estimates in Revman 5.2. Results: Database searches retrieved 1,016 records. A total of 17 studies containing 3,619 cases and 6,585 controls were finally included in our meta-analysis. The summary estimates suggested that organic dust exposure was positively associated with asthma (OR, 1.48; 95% CI, 1.26-1.75; P < 0.00001), whether among population-based case-control studies (OR, 1.24; 95% CI, 1.13-1.35; P < 0.00001) or hospital-based case-control studies (OR, 2.79; 95% CI, 1.27-6.12; P = 0.01). Subgroup analysis showed that paper/wood (OR, 1.62; 95% CI, 1.38-1.90; P < 0.00001), flour/grain (OR, 1.48; 95% CI, 1.11-1.97; P = 0.008), and textile dust (OR, 1.50; 95% CI, 1.08-2.09; P = 0.02) exposure were significantly associated with asthma. Conclusions: Based on the studies evaluated, our meta-analysis results prompt that organic dust exposure is a risk factor inducing asthma, although precise analysis focus on specific organic dust materials is still warranted.