Relationship of chronic kidney disease with major air pollutants - A systematic review and meta-analysis of observational studies

Background: Articles concerning the correlation of the risk of chronic kidney disease (CKD) with air contaminant exposure present inconsistent findings and the magnitude of the link is still unclear. Therefore, we planned to systematically and quantitatively investigate the overall strength of proofs in this field. Methods: Relevant articles on Cochrane, EMBASE, Medline, Web of Science, and CINHAL were searched as per relevant strategies. Only observational studies that disclosed the link of CKD risk with major air pollutants were enrolled, including PM10 and PM2.5, which were particulate matter less than 10 um and less than 2.5 um in erodynamic diameter respectively. Pooled relative risk (RR) and 95 % confidence interval (CI) were determined using random-effects models, regardless of the heterogeneity quantified by I-2 statistic. Results: Finally, 7 studies involving 5,812,381 participants were included. The incidence of CKD was increased by long-term exposure to PM10 (including solely estimated exposure to PM10 from studies using PM2.5) (RR 1.08, 95 %CI 1.04-1.11) with considerable heterogeneity (I-2 = 79 %), and the risk of CKD was raised by 8% when the long-time exposure to PM10 increased by 10 ug/m(3). The pooled RR (95 %CI) with a 10 mu g/m(3) increase in PM2.5 for risk of CKD was 1.09 (1.03-1.17). Stratified analysis also verified the general negative effects. Conclusions: Chronic subjection to major air contaminants (PM10 and PM2.5) is more likely to cause CKD. Thus, developing global approaches of air pollution elimination to prevent CKD is urgent.