Meta-analysis quantifies survival gains from bariatric surgery

Metabolic-bariatric surgery is associated with substantially lower all-cause mortality and longer life expectancy than usual care for obesity, a study found, and survival benefits are increased in people with diabetes.

Researchers compared long-term survival of severely obese patients who received metabolic-bariatric surgery versus usual care in a meta-analysis of 17 studies. In an attempt to avoid bias, they used rigorous criteria to select the studies and excluded articles that specifically enrolled patients with comorbidities other than diabetes. Among the 16 matched cohort studies and one prospective controlled trial included in the analysis, there were 174,772 participants and 7,712 deaths during 1.2 million patient-years. Results were published May 6 by The Lancet.

In the overall population, metabolic-bariatric surgery was associated with a reduction of 49.2% in all-cause mortality (95% CI, 46.3% to 51.9%, P<0.0001) and median life expectancy was 6.1 years (95% CI, 5.2 to 6.9 years) longer than with usual care. All-cause mortality was reduced with surgery in both patients with diabetes (hazard ratio [HR], 0.409 [95% CI, 0.370 to 0.453]; P<0.0001) and without (HR, 0.704 [95% CI, 0.588 to 0.843]; P<0.0001). The treatment effect was considerably greater for those with diabetes. Their gain in median life expectancy was 9.3 years (95% CI, 7.1 to 11.8 years) compared to 5.1 years (95% CI, 2.0 to 9.3 years) for patients without diabetes. Treatment effects did not appear to differ among gastric bypass, banding, and sleeve gastrectomy (P=0.36).

The authors calculated numbers needed to treat to prevent one additional death over a 10-year time frame of 8.4 (95% CI, 7.8 to 9.1) for adults with diabetes and 29.8 (95% CI, 21.2 to 56.8) for those without diabetes. They estimated that every 1% increase in metabolic-bariatric surgery rates among the global pool of candidates with and without diabetes could yield 5.1 million and 6.6 million potential life-years, respectively.

“Our meta-analysis adds to a growing evidence base supporting a role for metabolic-bariatric surgery in the management of obesity, especially in patients with type 2 diabetes,” they wrote. “These findings should be of interest to policy makers developing coordinated strategies to tackle the increasing prevalence of obesity and diabetes—and all their public health and economic consequences—as well as general practitioners, endocrinologists, and cardiologists who play a vital part in managing patients who are overweight and have cardiometabolic comorbidities.”