Bariatric Surgery Lowers Mortality, Risk of Events in Patients with Diabetes and Obesity

A new study is highlighting the potential benefits associated with bariatric surgery in patients with type 2 diabetes and obesity.

The study, which was a retrospective matched cohort study of nearly 7000 patients in Canada, found undergoing bariatric surgery was associated with a slew of benefits, including a 68% reduction in cardiac mortality and 34% reduction in cardiac events.

“Overall, this study reinforces that the glycemic benefit of bariatric surgery found in randomized clinical trials likely translates to a mortality benefit over time, and it supports the use of surgery as a first-line treatment for individuals with obesity and diabetes,” wrote investigators.

Led by Dennis Hong, MD, of the Division of General Surgery, St Joseph’s Healthcare, a team of investigators from multiple institutions throughout Ontario, Canada sought to provide within-strata data related to outcomes among patients with type 2 diabetes and obesity undergoing bariatric surgery or nonsurgical management. To do so, the team designed a retrospective, population-based matched cohort study using information derived from multiple linked administrative databases containing data of patients treated within the Ontario Bariatric Network from January 2010-December 2016.

The investigators’ initial search yielded more than 27,00 patients who underwent bariatric surgery during the study period. After exclusion of those with missing information and without type 2 diabetes, investigators identified 5986 potentially eligible patients for inclusion. Using data from the linked databases, investigators were able to match 3455 of these patients to 3455 nonsurgical controls. Of note, all patients included in the study had severe obesity, which was defined as a BMI of 35 kg/m2.

The study population had a mean BMI of 44.67 (SD, 7.9) kg/m2, mean age of 52.04 (SD, 9.45) years, 71.6% were women, and a median follow-up time of 4.6 (3.22-6.35) years. Among patients who underwent bariatric surgery, the most common procedure was gastric bypass (86.7%).

Data related to age, baseline BMI, sex, comorbidities, duration of diabetes diagnosis, health care utilization, socioeconomic status, smoking status, substance abuse, cancer screening, and psychiatric history were obtained from EMR data and included in investigators’ analyses as confounding factors.

For the purpose of analysis, investigators chose all-cause mortality as the primary outcome of their analyses. Secondary outcomes included cause-specific mortality and diabetes-related outcomes, which included composite cardiovascular and composite renal outcomes. The composite cardiovascular outcome was defined as cardiovascular mortality, nonfatal myocardial infarction, stroke, percutaneous coronary intervention, coronary artery bypass graft, transient ischemic stroke, deep vein thrombosis, or pulmonary embolism. The composite renal outcome was defined as new dialysis treatment or transplantation.

During the follow-up period, 83 (2.4%) patients in the surgery group died compared to 178 patients in the control group (HR, 0.53; 95% CI, 0.41-0.69; P <.001). Compared to nonsurgical management, bariatric surgery was associated with a 68% reduction in risk of cardiovascular mortality (HR, 0.32; 95% CI, 0.15-0.66; P=.002) and a 32% lower risk of the composite cardiovascular outcome (HR, 0.68; 95% CI,0.55-0.85; P <.001) . Additionally, undergoing bariatric surgery was associated with a 42% reduction in risk of the composite renal outcome (HR, 0.58; 95% CI, 0.35-0.95).

Further analysis identified multiple subgroups that appeared to have the greatest absolute benefit from bariatric surgery. The greatest benefit for mortality was seen among men (Absolute Risk Reduction [ARR], 3.7%; 95% CI, 1.7-5.7%), those with a duration of diabetes greater than 15 years (ARR, 4.3%; 95% CI, 0.8-7.8%), and those 55 years of age or older (ARR, 4.7%; 95% CI, 3.0-6.4%).

This study, “Association Between Bariatric Surgery and Major Adverse Diabetes Outcomes in Patients With Diabetes and Obesity,” was published in JAMA Network Open.