Cigarette smoking and chronic kidney disease in the general population: a systematic review and meta-analysis of prospective cohort studies

Background. Cigarette smoking has been established as a major risk factor for chronic kidney disease (CKD) development in people with diabetes. Conflicting evidence exists among representative community-based studies as to whether smoking is an independent risk factor for CKD. The aim of this meta-analysis was to assess the effects of tobacco smoking on the development of CKD in adult general populations. Methods. A literature search was conducted using MEDLINE and Embase from their inception through 31 May 2016 for prospective cohort studies that reported relative risks of CKD with smoking status in the general population. Summary relative risks (SRRs) and 95% confidence intervals (CIs) were calculated using a randomeffects model. Results. A total of 15 prospective cohort studies, including 65 064 incident CKD cases, were included. Compared with never-smokers, the SRRs of incident CKD were 1.27 (95% CI 1.19-1.35) for ever-smokers, 1.34 (95% CI 1.23-1.47) for current smokers and 1.15 (95% CI 1.08-1.23) for former smokers. The SRRs for end-stage renal disease development were 1.51 (95% CI 1.24-1.84) for ever-smokers, 1.44 (95% CI 1.00-2.09) for former smokers and 1.91 (95% CI 1.39-2.64) for current smokers. Considerable heterogeneity was observed among these studies. After combining an additional three prospective cohort studies, which involved 5747 incident proteinuria cases, a null smoking-proteinuria association in the general population was observed. Conclusions. Our meta-analysis suggests evidence for cigarette smoking as an independent risk factor for incident CKD. Future studies are required to investigate whether smoking cessation can decrease incident CKD in the general adult population.