Morbidity and mortality before and after bariatric surgery for morbid obesity compared with the general population

Background: Bariatric surgery reduces morbidity and mortality in obese subjects, but it is unclear how rates compare with those in the population. The aim was to assess the risk of admission to hospital for obesity-related co-morbidities and overall mortality after bariatric surgery in relation to the general population.

Methods: A nationwide, population-based cohort study was conducted of all patients who underwent bariatric surgery in Sweden between 1980 and 2006. Each patient was compared with ten age- and sex-matched controls randomly selected from the Total Population Register. Hospital admission for co-morbidities was identified through the Patient Register. Cox proportional regression was used to calculate hazard ratios (HRs).

Results: A total of 13 273 patients underwent bariatric surgery between 1980 and 2006. After surgery, the overall adjusted HR remained increased for myocardial infarction (HR 1·56, 95 per cent confidence interval 1·35 to 1·81), angina pectoris (HR 2·05, 1·84 to 2·31), stroke (HR 2·13, 1·88 to 2·42), hypertension (HR 2·80, 2·61 to 3·01), diabetes (HR 2·44, 2·23 to 2·67) and death (HR 1·24, 1·15 to 1·34) in these patients compared with the general population. The 4161 patients who underwent gastric bypass surgery no longer had a higher risk of diabetes (HR 1·23, 0·88 to 1·72) or myocardial infarction (HR 0·78, 0·42 to 1·45), whereas morbidity remained increased after restrictive surgery in 7855 patients. The adjusted mortality remained higher after both gastric bypass and restrictive surgery.

Conclusion: Gastric bypass, but not restrictive surgery, in patients with morbid obesity seems to reduce the risk of diabetes and myocardial infarction to population levels, but the risk of death remains increased.