Association between air pollutants and development of chronic kidney disease: A systematic review and meta-analysis

Background: The association between incident chronic kidney disease (CKD) or end-stage renal disease (ESRD) and exposure to outdoor air pollution is under debate. We aimed to examine this relationship based on a systematic review with random-effects meta-analysis. Methods: We screened the literature on long-term air pollution exposure assessment in the general population using an electronic search of PubMed, Medline, Embase, and Cochrane Library from inception to 20 October 2019. Observational studies investigating the association between long-term exposure to gaseous (CO, SO₂, NO₂, O₃) or particulate (PM_2.5 or PM₁₀) outdoor air pollutants and CKD, ESRD, or renal dysfunction were included, and summary risks were estimated. Results: Of 4419 identified articles, 23 met our inclusion criteria after screening and 14 were included in the meta-analysis. Pooled effect estimates had the following summary risk ratios (RRs) for CKD: 1.10 (95% confidence intervals [CI] 1.00, 1.21; derived from four studies) per 10 μg/m³ increase in PM_2.5 and 1.16 (95% CI 1.05, 1.29; derived from four studies) for PM₁₀; 1.31 (95% CI 0.86, 2.00; derived from two studies) per 10 ppm increase in CO; and 1.11 (95% CI 1.09, 1.14; derived from three studies) per 10 ppb increase in NO₂. For the pooled effect on eGFR, increases in PM₁₀ and PM_2.5 (of 10 μg/m³) were associated with eGFR decline by −0.83 (95% CI –1.54, −0.12; derived from two studies) and −4.11 (95% CI –12.64, 4.42; derived from two studies) mL/min/1.73 m², respectively. Conclusions: Air pollution was observed to be associated with CKD and renal function decline. Although more longitudinal studies are required, we argue that air pollution is pernicious to kidney health.