Importance: The association of bariatric surgery and specialized medical obesity treatment with beneficial and detrimental outcomes remains uncertain.
Objective: To compare changes in obesity-related comorbidities in patients with severe obesity (body mass index ≥40 or ≥35 and at least 1 comorbidity) undergoing bariatric surgery or specialized medical treatment.
Design, setting, and participants: Cohort study with baseline data of exposures from November 2005 through July 2010 and follow-up data from 2006 until death or through December 2015 at a tertiary care outpatient center, Vestfold Hospital Trust, Norway. Consecutive treatment-seeking adult patients (n = 2109) with severe obesity assessed (221 patients excluded and 1888 patients included).
Exposures: Bariatric surgery (n = 932, 92% gastric bypass) or specialized medical treatment (n = 956) including individual or group-based lifestyle intervention programs.
Main outcomes and measures: Primary outcomes included remission and new onset of hypertension based on drugs dispensed according to the Norwegian Prescription Database. Prespecified secondary outcomes included changes in comorbidities. Adverse events included complications retrieved from the Norwegian Patient Registry and a local laboratory database.
Results: Among 1888 patients included in the study, the mean (SD) age was 43.5 (12.3) years (1249 women [66%]; mean [SD] baseline BMI, 44.2 [6.1]; 100% completed follow-up at a median of 6.5 years [range, 0.2-10.1]). Surgically treated patients had a greater likelihood of remission and lesser likelihood for new onset of hypertension (remission: absolute risk [AR], 31.9% vs 12.4%); risk difference [RD], 19.5% [95% CI, 15.8%-23.2%], relative risk [RR], 2.1 [95% CI, 2.0-2.2]; new onset: AR, 3.5% vs 12.2%, RD, 8.7% [95% CI, 6.7%-10.7%], RR, 0.4 [95% CI, 0.3-0.5]; greater likelihood of diabetes remission: AR, 57.5% vs 14.8%; RD, 42.7% [95% CI, 35.8%-49.7%], RR, 3.9 [95% CI, 2.8-5.4]; greater risk of new-onset depression: AR, 8.9% vs 6.5%; RD, 2.4% [95% CI, 1.3%-3.5%], RR, 1.5 [95% CI, 1.4-1.7]; and treatment with opioids: AR, 19.4% vs 15.8%, RD, 3.6% [95% CI, 2.3%-4.9%], RR, 1.3 [95% CI, 1.2-1.4]). Surgical patients had a greater risk for undergoing at least 1 additional gastrointestinal surgical procedure (AR, 31.3% vs 15.5%; RD, 15.8% [95% CI, 13.1%-18.5%]; RR, 2.0 [95% CI, 1.7-2.4]). The proportion of patients with low ferritin levels was significantly greater in the surgical group (26% vs 12%, P < .001).
Conclusions and relevance: Among patients with severe obesity followed up for a median of 6.5 years, bariatric surgery compared with medical treatment was associated with a clinically important increased risk for complications, as well as lower risks of obesity-related comorbidities. The risk for complications should be considered in the decision-making process.