Original Title: Fedmekirurgi ved diabetes type 2 og kroppsmasseindeks under 35

Authors' objectives: The division for health services in the Norwegian Institute of Public Health has prepared a health technology assessment (HTA) comparing the effectiveness and safety of bariatric surgery with non-surgical interventions in the treatment of patients with Type 2 Diabetes and a body mass index (BMI) below 35. The report will also include a health economic evaluation of the use of bariatric surgery compared with non-surgical interventions. The HTA is intended to inform decision making by the Norwegian System for New Health Technologies.

Authors' results and conclusions: We included a total of 11 studies; four randomized (RCT), four prospective and two retrospective non-randomized controlled trials, and one large registry study with no control group. Of the 534 total patients included in the controlled studies, 257 were undergoing or were randomized to bariatric surgery. The registry study included 1,300 operated patients. One RCT and one non-randomized study used surgical methods that are not performed in the Norwegian specialist health care service. Follow-up was one or two years in most studies. Efficacy results were comparable between the randomized and non-randomized studies. Therefore, we only present the results for the meta-analysis of the randomized studies after two years. Nine out of ten controlled studies found higher rates of diabetes remission, defined as HbA1c values below 6.5%, in the surgery group compared to the control group. Diabetes remission occurred in 26 of 59 patients (44%) in the surgery group versus 2 out of 60 (3%) in the control group (RR = 8.73 [CI 2.52 to 30.17]). Furthermore, we found a significantly lower HbA1c concentration in the surgery group than in the control group with a mean difference of MD = -1.37% (CI -1.98 to -0.76) in favor of surgery. Fasting glucose concentrations were also significantly lower in the surgery group than in the control group (MD = -2.96 mmol/l [CI -5.28 to -0.64]). Health-related quality of life was assessed in only one study. The study found a statistically significant improvement in physical health, measured with the questionnaire SF-36, in the group that underwent band surgery compared to the group receiving drug treatment, but no significant difference between the groups in mental health. Nine out of ten studies found lower BMI or weight measured in kilograms after surgery compared to control treatment. Mean BMI reduction was MD = -4.10 kg/m2 (CI -6.30 to -1.90 to) more in the surgery group than in the control group. In the controlled studies, no deaths were reported in the surgery groups, while one death in the control groups was recorded. The registry study, with data for 1300 operated patients, reported a mortality rate of 0.15%, a serious morbidity of 0.7% and a combined morbidity of 4.2% during a follow-up period of 30 days. Reoperations occurred in 1.6% of patients. We have moderate confidence in the effect estimates for remission of diabetes, reduction in HbA1c concentrations and BMI. There were too few studies to do relevant subgroup analyses of weight classes and surgery methods. Health economics: Relatively few patients from the included studies received surgery types relevant for use in Norway. Therefore we considered the current documentation of clinical efficacy as insufficient to build a reliable and valid cost-effectiveness model that would reflect Norwegian clinical practice. For the assessment of economic aspects, we performed a cost analysis in a healthcare perspective. We estimated costs associated with bariatric surgery with one-year follow-up to between 83,500 and 118,000 Norwegian kroner (NOK) per patient. The estimate includes surgery costs, consultations, examinations and patient training before and after surgery. Costs associated with standard treatment in the form of intensive lifestyle intervention are estimated to between NOK 23,400 and NOK 52,200 per patient. The costs include outpatient consultations with a physician, nutritionist, sports teacher and group-based teaching in physical activity, diet and motivation. It is uncertain how many patients with type 2 diabetes and KMI under 35 that may be appropriate for surgical treatment. Conclusion: Bariatric surgery in patients with type 2 diabetes and a BMI below 35 can give a remission of diabetes and a lower concentration of HbA1c compared to pharmacological treatment. Confidence in this documentation is moderate. However, short follow-up in the included studies makes it difficult to predict the long term impact of bariatric surgery on health outcomes and costs for these patients. Effectiveness and safety beyond two years should be investigated in further studies.

Authors' methods: We conducted a systematic search for randomized and non-randomized controlled studies in May 2017. For assessment of safety, we also applied for studies without a control group (registry studies) with participant numbers above 500. A Swedish HTA that met our inclusion criteria, with a search from January 2016, was used as a basis for obtaining studies published before 2016. Risk of bias was evaluated for all studies. We used risk ratio (RR) for dichotomy outcomes, weighted mean difference (MD) for continuous outcomes and calculated 95% confidence interval (CI) for the effect estimates. The quality of evidence for each outcome was assessed using the GRADE tool. Confidence in the documentation, i.e., whether we trust that the effect estimate is close to a true underlying effect, is ranked as high, moderate, low or very low.

Project Status: Completed

Year Published: 2018

URL for published report: https://www.fhi.no/en/publ/2018/Bariatric-surgery-for-Type-2-Diabetes-and-a-body-mass-index-below-35/

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: Norway

Organisation Name: Norwegian Institute of Public Health

Contact Address: P.O. Box 222 Skoyen, N-0123, Oslo