Clinical Question

Is bariatric surgery associated with reductions in all-cause mortality or lower rates of obesity-related conditions?

Bottom Line

Based on population registry data, bariatric surgery is associated with lower all-cause mortality and a lower risk of developing many subsequent obesity-related conditions. Because the investigators excluded randomized trials, the patients' health habits and other unmeasured factors might account for the findings. (Level of Evidence = 2a–)

Synopsis

The authors searched PubMed, EMBASE, and the Web of Science for national or regional administrative database studies that evaluated mortality or incident obesity-related diseases for patients who have undergone any form of bariatric surgery. They defined obesity-related illnesses as type 2 diabetes mellitus, hypertension, obstructive sleep apnea, ischemic heart disease, cardiac failure, dyslipidemia, and venous thromboembolism. The authors excluded randomized trials but included studies that had a control group and a minimum of 18 months of follow-up. Two authors independently evaluated studies for inclusion. The authors did not describe searching for unpublished studies. They included 18 studies with 1,539,904 patients, in which 269,818 patients received some form of bariatric surgery: gastric bypass (n = 137,578, 51%), sleeve gastrectomy (n = 58,916, 22%), adjustable gastric band (n = 52,973, 20%), vertical banded gastroplasty (n = 6,397, 2%), biliopancreatic diversion (n = 1,002, 0.4%), or an alternative procedure or unspecified operation (n = 12,952, 5%). The median follow-up period was 59 months. The authors reported that the quality of the studies was high.

Eleven studies found a decreased association between surgery and all-cause mortality (odds ratio [OR] = 0.62; 95% CI, 0.55 to 0.69) with heterogeneity but no evidence for publication bias. Six studies found a decreased association between surgery and the subsequent development of type 2 diabetes (OR = 0.39; 95% CI, 0.18 to 0.83), but with statistical heterogeneity and no evidence for publication bias. Five studies found a lower risk of incident hypertension after surgery (OR = 0.36; 95% CI, 0.32 to 0.40) with no evidence for heterogeneity or publication bias. One study reported incident sleep apnea, which occurred in 1.1% of patients undergoing surgery compared with 2% of control patients. Five studies reported that incident ischemic heart disease was lower after surgery (OR = 0.46; 95% CI, 0.29 to 0.73), but with statistical heterogeneity and no evidence for publication bias. Two studies found no association between surgery and incident heart failure. One study reported venous thromboembolism, which occurred in 1.7% of patients undergoing surgery compared with 4.4% of control patients (hazard ratio = 0.60; 95% CI, 0.43 to 0.84). Because this analysis excluded randomized trials, it is possible that the magnitude of the lower risks of bad outcomes associated with bariatric surgery is inflated.

Study design: Meta-analysis (other)

Funding source: Government

Setting: Various (meta-analysis)

Reference: Wiggins T, Guidozzi N, Welbourn R, et al. Association of bariatric surgery with all-cause mortality and incidence of obesity-related disease at a population level: a systematic review and meta-analysis. PLoS Med. 2020;17(7):e1003206.