Patients with severe obesity and type 2 diabetes and without bariatric surgery are assessed to determine comparative incidence of macrovascular disease.
The umbrella term macrovascular disease encompasses both cardiovascular disease and cerebrovascular disease. These are among the most concerning complications of type 2 diabetes and, as such, are the subject of many preventative clinical interventions. Current evidence indicates that interventions focused on weight reduction confer a corresponding reduction in the risk of developing macrovascular disease. With regards to weight reduction via bariatric surgery, there is a small body of evidence that suggests a similar preventative benefit to other weight-reducing techniques. However, the quality of study that provides this evidence is a bit lacking, as the sample sizes are typically low and BMI is often not a measurement of interest. The aim of this study is to determine if there is a correlation between bariatric surgery and reduced macrovascular risk in patients with type 2 diabetes and severe obesity, while addressing the shortcomings of other studies with similar aims.
This study is a retrospective cohort study in design. The data used for the study was procured from the electronic medical records from four branches of the Health Care Systems Research Network (Kaiser Permanente Washington State as well as Northern and Southern California, and HealthPartners of Minnesota). Patient data was considered for use if the patient had a diagnosis of type 2 diabetes and underwent bariatric surgery between the years of 2005 and 2011. Patient data was excluded if there was less than 1 year of continuous enrollment in their respective health system, a history of cancer, pregnancy, metformin as the only indication of diabetes diagnosis, gestational diabetes, pre-existing cardiovascular or cerebrovascular disease, pre-procedure BMI of < 35, absent pre-procedure BMI or HbA1c, or unable to find characteristic matched patient without surgery. The non-surgical matched patients were considered based on the same criteria as the surgical patients (with the exception of undergoing bariatric surgery) then matched to a corresponding surgical patient based on pre-surgical baseline characteristics. The primary outcome of interest was time to first major macrovascular event (myocardial infarction, unstable angina, stent placement, ischemic or hemorrhagic stroke, etc.). Time to each individual type of event was assessed secondarily. Statistical significance was determined via the Cox proportional hazards regression model.
Of the 9,109 surgical cases that were considered for inclusion, 5,301 were deemed eligible and included in the study. There were 14,934 non-surgical matched patients who were also identified and included in the study. For the primary outcome, the patients who underwent a bariatric procedure had a lower incidence of macrovascular events at 5 years post-surgery when compared to their non-surgical matched counterparts (2.1 vs. 4.3% respectively). Likewise, there was a statistically significant reduction in cardiovascular events, favoring the surgical group during the same timeframe (1.6 vs. 2.8% for the surgical and non-surgical group respectively). There was no significant difference between groups with regards to occurrence of cerebrovascular events.
The results of this study indicate that undergoing bariatric surgery may provide a macrovascular risk reduction if the patient has severe obesity and has type 2 diabetes. This suggests that bariatric surgery may be an effective clinical option in this patient population if conventional lifestyle and pharmacologic options have failed. However, as this study is observational in nature, causation cannot be inferred. Therefore, further study, preferably with randomized controlled trials, is necessary in order to validate these findings.
- Weight reduction has been linked to decreased risk of macrovascular complications in patients with type 2 diabetes and obesity.
- Study shows a correlation between reduced macrovascular risk and weight reduction achieved via bariatric surgery in patients with type 2 diabetes and obesity.
- Undergoing bariatric surgery may provide a macrovascular risk reduction if the patient has severe obesity and type 2 diabetes.
Fisher, David P., et al. “Association Between Bariatric Surgery and Macrovascular Disease Outcomes in Patients With Type 2 Diabetes and Severe Obesity.” Jama, vol. 320, no. 15, 2018, p. 1570., doi:10.1001/jama.2018.14619.
Michael Zaccaro, Pharm. D. Candidate 2019, LECOM School of Pharmacy