Causes and risk factors for mortality within 1 year after obesity surgery in a population-based cohort study

Abstract Background The use of obesity surgery has increased during the past decade. There is a need for population-based assessments of causes and risk factors for postoperative mortality. The objective of this study was to assess causes and risk factors for 1-year mortality after obesity surgery. Methods This nationwide retrospective population-based cohort study included essentially all obesity surgery patients in Sweden from 1980–2010. Data were collected from Swedish national registries and medical records. Patient characteristics, co-morbidities, and surgical procedures were assessed in relation to 1-year mortality through multivariable Cox proportional hazards regression, providing hazard ratios (HR), and 95% confidence intervals (CI) adjusted for age, sex, surgical procedure, surgical access, and co-morbidity. Results Among 22,487 obesity surgery patients the 1-year cumulative mortality was .38% (n = 85). Follow-up of cohort was complete. Median time of postoperative death was 45 days. Main causes of death included cardiopulmonary complications (myocardial infarction [n = 14; 16%], pulmonary embolism [n = 12; 14%], sudden cardiac arrest [n = 11; 13%]), and anastomotic leak (n = 12; 14%). Male sex (HR = 2.31; 95% CI 1.48–3.60), diabetes (HR = 2.47; 95% CI 1.44–4.23), and congestive heart failure (HR = 4.82; 95% CI 2.25–10.35) were independently associated with increased 1-year mortality, while age, hypertension, cerebrovascular disease, coronary heart disease, chronic obstructive pulmonary disease, asthma, and surgical procedure were not. Open surgery entailed an increased mortality compared to laparoscopic surgery from 2000–2010 (HR = 2.72; 95% CI 1.53–4.83), but not from 1990–1999 (HR = .39; 95% CI .11–1.32). Conclusion Although the absolute risk of mortality is low, the increased relative risk of mortality associated with male sex, diabetes, congestive heart failure, and open surgical access could influence clinical decision making.