27th October 2019. Dr Chee L Khoo
We often hear about cardiovascular outcomes trials (COVT) involving the new anti-diabetic agents – the SGLT2 inhibitors, the DPP4 inhibitors and the GLP1-RAs. The CVOTs were meant to ensure that the agents do not have significant major adverse cardiovascular outcomes (MACE) when we prescribed them for patients with type 2 diabetes (T2D). All make sense as we need to make sure that post Phase 2 trials when these agents are used in hundreds of thousands of patients, they don’t cause more harm that good. What about metabolic or bariatric surgery? They achieved significant weight loss and often lead to diabetes remission in many patients. But are they safe? Do they cause more harm than good?
A retrospective, observational, matched-cohort study was conducted in adult patients with obesity and type 2 diabetes who underwent metabolic surgery within the Cleveland Clinic Health System. Patients who had a diagnosis of type 2 diabetes between January 1, 1998, and December 31, 2017 has received metabolic surgery were included in the study. Patients who were diagnosed with cancers, heart failure or organ transplant at the time of the first metabolic surgery were excluded.
The primary end points were a composite of 6-component MACE – first occurrence of:
- all-cause mortality,
- coronary artery events (unstable angina, myocardial infarction, or coronary intervention/surgery),
- cerebrovascular events (ischemic stroke, haemorrhagic stroke, or carotid intervention/surgery),
- heart failure,
- nephropathy, and
- atrial fibrillation).
A secondary composite end point included 3-component MACE:
- all-cause mortality,
- myocardial infarction, and
- ischemic stroke).
Of a total of 13 722 patients, 2287 underwent metabolic surgery. They were matched for most but not all, characteristics with 11 435 non-surgical control patients in the analysis. Patients in the surgery group had higher body weight, higher BMI, and higher rates of dyslipidaemia and hypertension.
The mean body weight at 8 years was reduced by 29.1 kg in the surgery group and 8.7 kg the non-surgical control group. Metabolic surgery was also associated with a significant reduction in HbA1c level. Use of non-insulin diabetes medications, insulin, renin-angiotensin system blockers, other anti-hypertensive medications, lipid-lowering therapies, and aspirin were also significantly lower after metabolic surgery compared with usual care.
At 8 year follow up, the primary end point occurred in 30.8% of the surgical group compared with 47.7% of the non-surgical group (p < .001) with the absolute risk difference of 16.9% and adjusted hazard ratio of 0.61. The cumulative incidence of 3-component MACE at 8 years was 17.0% compared with 27.6% in the usual care group with an absolute risk difference, 10.6% (HR, 0.62).
During the 8 year follow up, 112 (10.0%) patients in the surgical group and 1111 (17.8%) patients in the non-surgical group died. The absolute risk difference at 8-year follow-up was 7.8 with a hazard ratio 0.59.
Metabolic surgery was also associated with significantly lower incidence of the other 5 individual end points, including coronary artery events, cerebrovascular events, heart failure, nephropathy, and atrial fibrillation.
We can now reassure our patients contemplating metabolic surgery that metabolic surgery is associated to significantly lower mortality and morbidity. It not just for looks.
Access this abstract here.
Aminian A, Zajichek A, Arterburn D, et al. Association of Metabolic Surgery With Major Adverse Cardiovascular Outcomes in Patients With Type 2 Diabetes and Obesity. JAMA. 2019;322(13):1271-1282