Smoking cessation and atherosclerotic cardiovascular events and mortality in chronic kidney disease

Abstract Background Smoking cessation is recommended to reduce excess atherosclerotic cardiovascular disease (ASCVD) and mortality in patients with chronic kidney disease (CKD). However, this recommendation is largely based on observational studies on the general population Therefore, we aimed to evaluate the association of smoking dose and smoking cessation duration with ASCVD and mortality in patients with CKD. Methods We compiled a comprehensive pooled dataset comprising 66 245 participants with CKD from the KNOW-CKD and the UK Biobank cohort. Additionally, we included 307 353 participants without CKD from the UK Biobank cohort. Participants were categorized according to smoking dose and duration of smoking cessation base on a questionnaire. The primary outcome was a composite of ASCVD events or all-cause mortality. Results Over a median follow-up period of 13.2 years, 14 671 (22.1%) participants reached the primary outcome. In the pooled CKD cohort, compared to never smokers, former and current smokers exhibited a 1.30- and 2.14-fold higher risk of the primary outcome, respectively. Among former smokers, the hazard ratios (HRs) (95% confidence intervals [CIs]) for smoking loads < 20 and ≥ 20 pack-years were 1.05 (1.00–1.10) and 2.14 (2.05–2.25), respectively. The increased risk of the primary outcome was attenuated by longer smoking cessation. The HRs (95% CIs) for smoking cessation of < 10 years, 10–20 years, and ≥ 20 years were 1.75 (1.65–1.86), 1.43 (1.34–1.52), and 1.11 (1.06–1.16), respectively, compared with never smokers. This association was also observed in individuals without CKD, but the risk was comparable between former smokers with smoking cessation ≥ 20 years and non-smokers, suggesting that a longer cessation is required in patients with CKD to offset the smoking-related adverse effects. Conclusions Among former smokers with CKD, the risk of ASCVD or mortality was substantially attenuated with less smoking load and a longer duration of smoking cessation.