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STAMPEDE trial

Study finds surgery better than medical therapy alone

Philip R Schauer, the lead investigator of the clinical trial.
Study shows that obese T2DM patients achieve glycaemic control more often with bariatric surgery than with medical therapy alone
42% of gastric-bypass patients achieved primary glycated haemoglobin level at 12 months, compared to 12% of medical-therapy patients
Trial concentrated on patients with more advanced T2DM

The results of the Surgical Treatment and Medications Potentially Eradicate Diabetes Efficiently (STAMPEDE) trial, published online in the March 2012 edition of the New England Journal of Medicine, have found that in obese patients with uncontrolled type 2 diabetes, 12 months of medical therapy plus bariatric surgery achieved glycaemic control in significantly more patients than medical therapy alone.

STAMPEDE is a randomised, controlled, single-centre study, designed to compare intensive medical therapy with surgical treatment (gastric bypass or sleeve gastrectomy) as a means of improving glycaemic control in obese patients with type 2 diabetes.

Study design

From March 2007 to January 2011, 218 patients were screened at the Cleveland Clinic, Ohio, USA, and 150 eligible patients from this group were assigned to undergo intensive medical therapy alone or intensive medical therapy plus either Roux-en-Y gastric bypass or sleeve gastrectomy. Eligibile patients were between 20 to 60 years old, with a diagnosis of type 2 diabetes (glycated haemoglobin level >7.0%), and a BMI of 27 to 43. Patients were excluded if they had undergone previous bariatric surgery or other complex abdominal surgery, or had poorly controlled medical or psychiatric disorders. 

All patients received intensive medical therapy, as defined by American Diabetes Association guidelines, including lifestyle counselling, weight management, frequent home glucose monitoring, and the use of newer drug therapies. The goal of medical management was modification of diabetes medications until the patient reached the therapeutic goal of a glycated haemoglobin level of 6.0% or less or became intolerant to the medical treatment. 

Bariatric procedures were performed laparoscopically by a single surgeon. Gastric bypass consisted of the creation of a 15- to 20ml gastric pouch, a 150cm Roux limb, and a 50cm biliopancreatic limb. Sleeve gastrectomy involved a gastric-volume reduction of 75 to 80% by resecting the stomach alongside a 30Fr endoscope beginning 3cm from the pylorus and ending at the angle of His.

The primary end point was the proportion of patients with a glycated haemoglobin level of 6% or less (with or without diabetes medications) 12 months after randomisation. Secondary end points included levels of fasting plasma glucose, fasting insulin, lipids, and high-sensitivity C-reactive protein (CRP); the homeostasis model assessment of insulin resistance (HOMA-IR) index; weight loss; blood pressure; adverse events; coexisting illnesses; and changes in medications.

Results

After 12 months, 140 patients (93%) completed all analyses (eight patients were lost during follow-up: one who did not undergo sleeve gastrectomy and seven in the medical-therapy group who did not have any follow-up visits). Another two patients in the medical-therapy group missed follow-up visits at nine and 12 months. The outcomes revealed that there were no significant differences in patients’ characteristics in the three study groups at baseline. The mean BMI was 36, with 51 of 150 patients (34%) with a BMI <35. The mean (±SD) age of the patients was 49±8 years, and 66% were women. The average glycated haemoglobin level was 9.2±1.5%. 

The primary target of glycated haemoglobin level of 6.0% or less at 12 months occurred in five of 41 patients (12%) in the medical-therapy group, compared with 21 of 50 (42%) in the gastric-bypass group (p=0.002) and 18 of 49 (37%) in the sleeve-gastrectomy group (p=0.008). There were no significant differences in the primary end point between the two surgical groups (p=0.59). All patients in the gastric-bypass group who achieved the target glycated haemoglobin level did so without medications, compared with five of 18 patients (28%) in the sleeve-gastrectomy group (who required the use of one or more glucose-lowering drugs). There was no significant heterogeneity among the subgroups stratified according to median age, BMI, use of insulin, or duration of diabetes.

At 12 months, mean levels of glycated haemoglobin and fasting plasma glucose were significantly lower in the two surgical groups than in the medical therapy group (p<0.01 for both comparisons). The researchers noted an improvement at three months in levels of glycated haemoglobin and fasting plasma glucose after each of the surgical procedures. This improvement was sustained over 12 months of observation with reduced hypoglycaemic medication use. 

“However, patients receiving medical therapy alone had a smaller and more gradual improvement in glycaemic control with some attenuation observed over the final six months, despite an increase in the use of hypoglycaemic medications,” the authors noted.

Greater changes were observed at one year after gastric bypass and sleeve gastrectomy in body weight, BMI, waist circumference and waist-to-hip ratio than after medical therapy. The mean percentage of weight loss among patients undergoing either gastric bypass or sleeve gastrectomy was greater (−27.5±7.3% and −24.7±6.6%, respectively) than among those receiving medical therapy alone (−5.2±7.7%) (p<0.001 for both comparisons). Changes in weight and in BMI were greater after gastric bypass than after sleeve gastrectomy (p=0.02 and 0.03, respectively). The percent of excess weight loss for gastric bypass (88%) and sleeve gastrectomy (81%) was superior to that of medical therapy (13%) (p<0.001 for both comparisons). In addition, both surgical groups had a significantly greater decrease in BMI over time than did the medical therapy group. 

There were no deaths, episodes of serious hypoglycemia requiring intervention, malnutrition, or excessive weight loss among the three groups. Although additional surgical interventions were required in four patients, including laparoscopic procedures for blood-clot evacuation, assessment of nausea and vomiting, and cholecystectomy after gastric bypass and jejunostomy for feeding access to treat a gastric leak after sleeve gastrectomy. 

“In our trial, patients had more advanced type 2 diabetes, with an average disease duration of more than eight years and a mean baseline glycated hemoglobin level of 8.9 to 9.5% while undergoing treatment with an average of nearly three diabetes agents, including a relatively high use of insulin (44% of patients) or other injectable therapies (14%),” the authors wrote. “The inclusion of patients with more advanced type 2 diabetes in the STAMPEDE trial probably explains the lower observed rate of diabetes remission; other differences from previous trials included less severe obesity, a greater proportion of men and black patients, and an older age.”

They add that in this study most differences between the gastric-bypass group and the sleeve-gastrectomy group were not significant, although it should be noted that the study was not adequately powered to detect modest differences between these two surgical procedures. 

“We conclude that bariatric surgery represents a potentially useful strategy for management of uncontrolled diabetes, since it has been shown to eliminate the need for diabetes medications in some patients and to markedly reduce the need for drug treatment in others,” they authors concluded. “In addition, among patients undergoing surgery, cardiovascular risk factors improved, allowing reductions in lipid-lowering and antihypertensive therapies. Theoretically, such improvements have the potential to reduce cardiovascular morbidity and mortality, as shown in nonrandomized studies, although such benefits will need to be balanced with surgical risk and safety as shown in larger, multi-centre clinical-outcome trials.”

The trial, which is expected to be complete in January 2016, was supported by a grant from Ethicon Endo-Surgery, the National Institutes of Health and LifeScan.

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