All-Cause Mortality Following Bariatric Surgery in Smokers and Non-smokers

Introduction: Bariatric surgery is associated with lower all-cause mortality, but many studies exclude smokers. We sought to determine if the association of mortality and bariatric surgery differs between smokers and non-smokers. Materials and Methods: We conducted a retrospective cohort study in a large Israeli integrated payer/provider health care organization. A total of 7747 adult patients who underwent bariatric surgery between January 1, 2005, and December 31, 2014, were selected and compared with non-surgical patients (and were matched on age, sex, diabetes, and BMI using a sequential/simultaneous stratification matching). A total of 30,742 patients with a median follow-up of 4.3 years were included in this study with less than 1% lost to follow-up. The type of bariatric surgery (gastric banding, Roux-en-Y gastric bypass, or sleeve gastrectomy) and smoking status were determined from electronic health records. The rate of all-cause mortality in matched surgical and non-surgical patients was compared in smoking and non-smoking subgroups, adjusted for key potential confounders. Results: There was a statistically significantly higher mortality associated with not having bariatric surgery in both smoking (HR, 1.99; 95% CI, 1.54–2.56) and non-smoking (HR, 1.93; 95% CI, 1.12–3.34) subgroups. Although smokers had higher rates of mortality overall (2.6% in smokers compared with 1.7% in non-smokers), the mortality hazard ratio (comparing matched non-surgical patients to surgical patients) did not differ significantly between smokers and non-smokers (p for interaction =.67). Conclusions: Bariatric surgery was associated with significantly lower mortality in both smokers and non-smokers.