Secondhand smoke and CKD

Abstract

Background and objectivesActive smoking is associatedwith higher risk of various diseases.However, the risk of CKD development in nonsmokers exposed to secondhand smoke is notwell elucidated. We aimed to investigate the association between secondhand smoke exposure and the risk of CKD development among never-smokers. Design, setting, participants,& measurementsAtotal of 131,196 never-smokers with normal kidney function,who participated in the Korean Genome and Epidemiology Study from2001 to 2014,were analyzed. The participants were classified into three groups on the basis of frequency of secondhand smoke exposure, assessed with survey questionnaires; no exposure, <3 days perweek, and ≥3 days per week. The association between secondhand smoke and CKD, defined as eGFR<60 ml/min per 1.73 m2, was examined in the cross-sectional analysis. In addition, the risk of incidentCKDdevelopmentwas analyzedin a longitudinal cohort of 1948 participantswithout CKD at baseline, which was a subset of the main cohort. Results The mean age of participants was 53 years, and 75% were women. Prevalent CKD was observed in 231 (1.8%), 64 (1.7%), and 2280 (2.0%) participants in the ≥3 days per week, <3 days per week, and no exposure groups. The odds ratio (OR) of prevalent CKD was significantly higher in the groups exposed to secondhand smoke than the no exposure group (<3 days per week:OR, 1.72; 95% confidence interval [95% CI], 1.30 to 2.27; and≥3 days perweek:OR, 1.44; 95%CI, 1.22 to 1.70). During amean follow-up of 104 months,CKDoccurred in 319 (16%) participants. Multivariable Cox analysis revealed that the risk for CKD development was higher in participants exposed to secondhand smoke than the no exposure group (<3 days perweek: hazard ratio, 1.59; 95% CI, 0.96 to 2.65; and ≥3 days per week: hazard ratio, 1.66; 95% CI, 1.03 to 2.67). Conclusions Exposure to secondhand smoke was associated with a higher prevalence of CKD as well as development of incident CKD.