Smoking Cessation Lowers Excess Mortality as Quickly as 3 Years After Cessation

Background: Cigarette smoking is a major cause of premature death. The extent and rapidity at which smoking cessation reduces mortality and smoking-related diseases is uncertain. Objective: To quantify the benefits of smoking cessation on cause-specific mortality. Design/Methods: Individual-level meta-analysis of 4 national observational health cohorts linked to death registries in the United States, United Kingdom, Norway, and Canada including adults aged 20 to 79 years from 1974 to 2018. The primary outcome was excess risk and cause-specific mortality differences between current or former smokers and never smokers. Results: This study included 1.48 million adults with mean follow-up time of 14.8 years and 122,697 deaths recorded. Current smokers had a higher hazard ratio for death compared to never smokers, 2.8 for women and 2.7 for men. Hazard ratios for death for former smokers versus never smoker were 1.3 for both men and women, which was less than half the hazard ratio for curr more...