Bariatric Times

FEB 2018

A peer-reviewed, evidence-based journal that promotes clinical development and metabolic insights in total bariatric patient care for the healthcare professional

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Review 17 Bariatric Times • February 2018 findings of major studies investigating long-term (beyond 5 years of follow-up) outcomes of bariatric surgery in patients with obesity and T2DM regarding sustainability and maintenance of weight loss, T2DM prevention, remission and relapse, cardiometabolic risk factors, micro- and macrovascular complications, and mortality. Durability of weight loss. The SOS (Swedish Obese Subjects) study represents a landmark in the field, investigating the short-, mid- and long-term effects of surgery up to 20 years postoperatively. It is a prospective matched-cohort study conducted in Sweden with a recruitment period of 1987–2001. 34 In this study, body weight remained reduced by 16 percent 10 years after surgery, while it increased by 1.6 percent in the matched control group. 35 In a prospective Utah-based study, over 1,000 patients with obesity who had RYGB were included. Weight loss reached 28 percent up to six years after surgery, and RYGB achieved superior weight loss maintenance compared to control interventions; 94 percent of RYGB-treated patients maintained at least 20 percent of their initial weight loss at two years; and 76 percent maintained at least 20 percent at six years. 36 These findings are consistent with a "set point change" for weight in the subcortical areas of the brain, which suggests that postoperatively, the subcortical areas of the brain are "under the impression" that patients are 25 to 30 percent overweight, and thus the bodyweight is brought down to the new level where the set point is now established. T2DM prevention, remission, relapse. A prespecified secondary endpoint of the SOS study was the incidence of new-onset T2DM during 15 years of follow-up in a large number of patients with obesity undergoing bariatric surgery versus matched controls with obesity. New-onset T2DM was reported in 6.8 cases per 1,000 patient-years in the surgical group compared to 28.4 cases per 1,000 patient-years in the control group. 37 Of interest, the effect of bariatric surgery to prevent T2DM by reducing incidence was influenced by the presence of impaired fasting glucose at baseline (prediabetes) but not by preoperative BMI. This finding provided ground for addressing the need to revisit the current BMI- centric eligibility criteria for bariatric surgery. 37 In the five-year follow-up study by Mingrone et al comparing RYGB/BPD to conventional medical treatment in patients with poorly controlled obesity and long-standing T2DM, 50 percent of surgically treated patients maintained partial T2DM remission at five years, whereas zero percent achieved complete T2DM remission at five years. 8 Recurrence of T2DM was observed in half of the patients who achieved a two-year T2DM remission after RYGB and one-third of patients who achieved a two-year remission after BPD, and was unrelated to the magnitude of weight loss. This was one of the first studies clearly indicating that continued monitoring of glycemic control after bariatric surgery is warranted, despite initial T2DM remission, due to the existing risk of hyperglycemia recurrence. In the recently published five-year follow-up of the STAMPEDE trial, the primary endpoint of achieving HbA1c less than six percent with or without antidiabetic medication was achieved by 29 percent of the RYGB group and 23 percent of the SG group, compared to only five percent of the IMT group. 38 This effect was seen in parallel with superior weight loss, better lipid profile, lower use of insulin, and improved quality of life after both surgical procedures. 38 Micro- and macrovascular complications of T2DM. In the study by Mingrone et al, major diabetes-related complications, including acute myocardial infarction, were reported in nearly one-third of medically treated patients compared to only one case in the RYGB group and zero cases in the BPD group. 8 Dramatically reduced renal and cardiovascular complications have been documented up to 10 years after BPD compared to nonsurgical approaches, indicating long-term benefits of this type of surgery on T2DM-related life-threatening complications. In support of this, a case-controlled Italian study investigated patients with obesity and newly-diagnosed T2DM showed that mean glomerular filtration rate (GFR) declined by nearly 50 percent in the medical arm and increased by 13.6 percent in the surgical arm during a follow-up of 10 years after BPD. After 10 years, all patients who had BPD had their microalbuminuria restored to normal, whereas microalbuminuria progressed to macroalbuminuria in conventionally treated patients. 39 In a long-term observational follow- up of the SOS study (extending up to 15 years), the cumulative incidence of microvascular diabetes-related complications was two-fold higher in the control group versus the surgical group (41.8 vs. 20.6 cases per 1,000 person-years), whereas the respective incidence of macrovascular diabetes- related complications (stroke and/ or myocardial infarction) was 44.2 cases in the control and 31.7 cases in the surgical group. 40 Prospective interventional studies suggest that diabetic nephropathy might improve within one year, but retinopathy and neuropathy remain stable for one year and might require longer to show improvements. 41–43 Cardiovascular risk factors. The SOS study showed that the rates of T2DM, dyslipidemia, hypertension, and hyperuricemia resolution were significantly higher and the respective incidence rates were significantly lower 10 years after bariatric surgery, compared to the control group. 35 More specifically, the rate of recovery for hypertriglyceridemia was 80 percent, low HDL cholesterol 73 percent, high LDL 72 percent, and hypertension 62 percent over a period of at least six years post-surgery. 44 The incidence of cardiovascular events was reduced by 33 percent, but only in patients with hyperinsulinemia, while BMI was not able to predict any benefit. 45 Low- grade systemic inflammation, which characterizes obesity and diabetes, also improved after all bariatric operations. 46 Survival and mortality. Bariatric surgery has been associated with improved long-term survival and reduced overall and cause- specific mortality related to T2DM, cardiovascular disease, and cancer. 47,48 Reduced all-cause mortality at five years and up to 10 years (mid- and long-term) has been reported in both male and female populations, 49 and patients with T2DM or hyperinsulinemia apparently benefit more. Bariatric surgery has been also associated with a reduced incidence of cancer, although only in women. 50 COMPARATIVE EVALUATION OF DIFFERENT SURGICAL PROCEDURES ON CARDIOMETABOLIC OUTCOMES The gradient of efficacy for the four well-established procedures for weight loss and T2DM remission is BPD > RYGB > SG > LAGB. The opposite gradient has been proposed for their comparative safety. 15 Among the four operations, RYGB appears to have the most favorable risk-benefit profile in most patients with T2DM. Although longer-term data are needed, current information suggests that SG is quite effective, resulting in excellent weight loss and major improvements in T2DM, at least in the short to medium term (1–3 years). It is a valuable option for patients with morbid obesity and T2DM, especially in those concerned about the risk of operations involving bowel diversion. 51 LAGB is effective in improving glycemia in patients with obesity and T2DM, to the degree that it results in weight loss. It is associated, however, with a greater risk of reoperation due to failure or band-related complications. Although clinical evidence suggests that BPD might be the most effective procedure in terms of glycemic control and weight loss, it is associated with a significant risk of nutritional deficiencies, making its risk-benefit profile less favorable. BPD should be primarily reserved for patients with extreme obesity (BMI >60kg/m 2 ) in centers with significant experience to monitor these patients long term. 15 POTENTIAL FOR LESS INVASIVE, DEVICE-BASED, TECHNIQUES The EndoBarrier® gastrointestinal liner (GI Dynamics, Boston, Massachusetts) is less invasive compared to bariatric surgery and totally reversible (Editor note: this device is no longer approved for use in the United States). The liner can be applied as a bridge to induce rapid weight loss prior to surgery and has shown satisfactory short-term weight loss results in multicentric, randomized efficacy studies. 52 It is placed endoscopically (mean procedure time: 35 minutes for implantation, approximately 17 minutes for explantation). The majority of patients experience at least one adverse event during the first week post-implantation, mainly mild abdominal pain and nausea. A systematic review and meta-analysis of five RCTs and 10 observational studies evaluating the liners efficacy and safety in patients with obesity with or without T2DM suggested that it might provide better weight loss than diet modification alone. 53 However, differences in glycemic endpoints, such as HbA1c and fasting plasma glucose, failed to reach statistical significance. Major adverse events included abdominal pain, nausea, and vomiting, while no fatal outcomes were reported. 53 Saline-filled intragastric balloon devices are reversible endoscopic approaches designed to occupy stomach volume and reduce food intake. A dual balloon system device (DBS) plus diet and exercise was compared to a lifestyle intervention alone in the REDUCE trial, a prospective RCT of DBS for the treatment of obesity. Three hundred and twenty-six patients with Grade I and II obesity were randomized to endoscopic DBS plus diet or sham endoscopy plus diet. The devices were extracted six months after implantation. DBS was found to be significantly more effective than diet in promoting weight loss, with a relatively acceptable safety profile (mainly gastric ulcers). 54 CRITICAL APPRAISAL OF CURRENT METABOLIC SURGERY GUIDELINES FOR DIABETES TREATMENT Recently, a number of leading international diabetes organizations issued new guidelines for the treatment of patients with obesity and The gradient of efficacy for the four well-established procedures for weight loss and T2DM remission is: BPD > RYGB > SG > LAGB. The opposite gradient has been proposed for their comparative safety. 15

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