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Original Investigation
October 16, 2018

Association Between Bariatric Surgery and Macrovascular Disease Outcomes in Patients With Type 2 Diabetes and Severe Obesity

Author Affiliations
  • 1The Permanente Medical Group, Kaiser Permanente Northern California, Oakland
  • 2Kaiser Permanente Washington Health Research Institute, Seattle
  • 3Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
  • 4Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena
  • 5HealthPartners Institute, HealthPartners, Minneapolis, Minnesota
  • 6RAND Corporation, Santa Monica, California
  • 7Institute for Health Research, Kaiser Permanente Colorado, Aurora
  • 8Division of Research, Kaiser Permanente Northern California, Oakland
JAMA. 2018;320(15):1570-1582. doi:10.1001/jama.2018.14619
Key Points

Question  For patients with severe obesity and type 2 diabetes, is there an association between bariatric surgery and incident macrovascular disease (defined as first occurrence of acute myocardial infarction, unstable angina, percutaneous coronary intervention, coronary artery bypass grafting, ischemic stroke, hemorrhagic stroke, carotid stenting, or carotid endarterectomy)?

Findings  In this retrospective cohort study of patients with type 2 diabetes and severe obesity that included 5301 who underwent bariatric surgery and 14 934 control patients without surgery, bariatric surgery was associated with a significantly lower risk of macrovascular events at 5 years’ follow-up (2.1% vs 4.3% at 5 years; hazard ratio, 0.60).

Meaning  Bariatric surgery was associated with a lower risk of incident major macrovascular events.

Abstract

Importance  Macrovascular disease is a leading cause of morbidity and mortality for patients with type 2 diabetes, and medical management, including lifestyle changes, may not be successful at lowering risk.

Objective  To investigate the relationship between bariatric surgery and incident macrovascular (coronary artery disease and cerebrovascular diseases) events in patients with severe obesity and type 2 diabetes.

Design, Setting, and Participants  In this retrospective, matched cohort study, patients with severe obesity (body mass index ≥35) aged 19 to 79 years with diabetes who underwent bariatric surgery from 2005 to 2011 in 4 integrated health systems in the United States (n = 5301) were matched to 14 934 control patients on site, age, sex, body mass index, hemoglobin A1c, insulin use, observed diabetes duration, and prior health care utilization, with follow-up through September 2015.

Exposures  Bariatric procedures (76% Roux-en-Y gastric bypass, 17% sleeve gastrectomy, and 7% adjustable gastric banding) were compared with usual care for diabetes.

Main Outcomes and Measures  Multivariable-adjusted Cox regression analysis investigated time to incident macrovascular disease (defined as first occurrence of coronary artery disease [acute myocardial infarction, unstable angina, percutaneous coronary intervention, or coronary artery bypass grafting] or cerebrovascular events [ischemic stroke, hemorrhagic stroke, carotid stenting, or carotid endarterectomy]). Secondary outcomes included coronary artery disease and cerebrovascular outcomes separately.

Results  Among a combined 20 235 surgical and nonsurgical patients, the mean (SD) age was 50 (10) years; 76% of the surgical and 75% of the nonsurgical patients were female; and the baseline mean (SD) body mass index was 44.7 (6.9) and 43.8 (6.7) in the surgical and nonsurgical groups, respectively. At the end of the study period, there were 106 macrovascular events in surgical patients (including 37 cerebrovascular and 78 coronary artery events over a median of 4.7 years; interquartile range, 3.2-6.2 years) and 596 events in the matched control patients (including 227 cerebrovascular and 398 coronary artery events over a median of 4.6 years; interquartile range, 3.1-6.1 years). Bariatric surgery was associated with a lower composite incidence of macrovascular events at 5 years (2.1% in the surgical group vs 4.3% in the nonsurgical group; hazard ratio, 0.60 [95% CI, 0.42-0.86]), as well as a lower incidence of coronary artery disease (1.6% in the surgical group vs 2.8% in the nonsurgical group; hazard ratio, 0.64 [95% CI, 0.42-0.99]). The incidence of cerebrovascular disease was not significantly different between groups at 5 years (0.7% in the surgical group vs 1.7% in the nonsurgical group; hazard ratio, 0.69 [95% CI, 0.38-1.25]).

Conclusions and Relevance  In this observational study of patients with type 2 diabetes and severe obesity who underwent surgery, compared with those who did not undergo surgery, bariatric surgery was associated with a lower risk of macrovascular outcomes. The findings require confirmation in randomized clinical trials. Health care professionals should engage patients with severe obesity and type 2 diabetes in a shared decision making conversation about the potential role of bariatric surgery in the prevention of macrovascular events.

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