Although patients who undergo bariatric surgery have reduced mortality, they are more prone to gastrointestinal complications than matched controls, according to the largest long-term follow-up study to date.

French researchers used a national database to follow all patients who had undergone either gastric bypass or a sleeve gastrectomy in 2009 for a mean of 6.8 years.

Nearly 9000 patients with obesity (82% female, mean age 40) who had the procedure were matched one-to-one with patients who were hospitalised for obesity in 2009 but did not have the surgery.

Patients who underwent gastric bypass had 36% lower mortality and those with sleeve gastrectomy had a 72% lower mortality rate than their matched controls over the follow-up period.