Patients matched for age, sex, number of comorbidities
Quebec has a single public health care system that covers the cost of bariatric surgery for eligible patients; that is, those with a BMI greater than 35 kg/m2 and comorbidities or a BMI greater than 40 kg/m2.
Using this provincial health care database, which covers over 97% of the population, the researchers identified 3,637 patients with diabetes and/or hypertension who had bariatric surgery during 2007-2012.
They matched the surgery patients with 5,420 control patients with obesity who lived in the same geographic region and had a similar age, sex, and number of Charlson Comorbidity Index comorbidities, but did not undergo bariatric surgery.
The patients had a mean age of 50 and 64% were women.
Half had zero to one comorbidities, a quarter had two comorbidities, and another quarter had at least three comorbidities.
Most patients in the surgery group had type 2 diabetes (70%) and 50% had hypertension, whereas in the control group, most patients had hypertension (82%) and 41% had diabetes.
The most common type of bariatric surgery was adjustable gastric banding (42% of patients), followed by duodenal switch (24%), sleeve gastrectomy (23%), and Roux-en-Y gastric bypass (11%).
The primary outcome was the incidence of MACE, defined as coronary artery events (including myocardial infarction, percutaneous coronary intervention, and coronary artery bypass graft), stroke, heart failure, and all-cause mortality,
After a median follow-up of 7-11 years, fewer patients in the surgical group than in the control group had MACE (20% vs. 25%) or died from all causes (4.1% vs. 6.3%, both statistically significant at P < .01)
Similarly, significantly fewer patients in the surgical group than in the control group had a coronary artery event or heart failure (each P < .01).
However, there were no significant between-group difference in the rate of stroke, possibly because of the small number of strokes.
The risk of MACE was 17% lower in the group that had bariatric surgery than in the control group (adjusted hazard ratio, 0.83; 95% confidence interval, 0.78-0.89), after adjusting for age, sex, and number of comorbidities.
In subgroup analysis, patients who had adjustable gastric banding, Roux-en-Y gastric bypass, or duodenal switch had a significantly lower risk of MACE than control patients.
The risk of MACE was similar in patients who had sleeve gastrectomy and in control patients.
However, these subgroup results need to be interpreted with caution since the surgery and control patients in each surgery type subgroup were not matched for age, sex, and comorbidities, said Dr. Bouchard.
He acknowledged that study limitations include a lack of information about the patients’ BMI, weight, medications, and glycemic control (hemoglobin A1c).
Dr. Bouchard and Dr. Anvari have no relevant financial disclosures.