Implantable Gastric Stimulation for the Treatment of Obesity in Adults: A Systematic Review A Systematic Review Blair Monell, PA-S Pacific University School of Physician Assistant Studies, Hillsboro, OR USA Results The SHAPE trial was a randomized, double-blind, placebo- controlled, multicenter study trial, including 190 participants. After 12 months of treatment there was no statistically significant difference in the percentage of excess weight loss between the treatment and control groups. At the conclusion of the study the control group lost 11.7% % of their excess weight and the treatment group lost 11.8% % of their excess weight. In a small, non-blinded study of 24 obese adults, 14 patients lost weight with a mean 13.9% estimated weight loss (EWL) and 10 patients gained weight with a mean 8.2% estimated weight gain. Further, in a second small, non-blinded study of 12 obese adults, the authors reported that at 20 weeks a statistically significant body weight decrease from kg kg to kg kg corresponding to an EWL of 17.6% + 4.3% occurred. All three studies evaluated device safety and found the implantable GES Transcend and Tantalus devices to be well tolerated and safely laparoscopically implanted with no deaths and few adverse side effects. The most common safety concern was lead penetration of the stomach lumen at implantation. Introduction Currently, greater than one in three American adults are obese, as defined by a Body Mass Index (BMI) of > 30 kg/m 2. Annually, obesity is responsible for an estimated 2.8 million unnecessary deaths in the US. This makes obesity at least equal to smoking as a preventable cause of premature death. Conservative lifestyle alterations such as diet and exercise are proving to be insufficient in combating obesity. In fact, rates of obesity have increased 1.1 percentage points since The continuing trend toward an increasing adult BMI reflects an urgent need for more affordable, more effective and overall safer bariatric treatment alternatives. Implantable gastric electrical stimulation (GES) offers a novel, minimally invasive surgical approach to promote weight loss. Unlike other obesity surgeries, gastric electrical stimulation (GES) does not rely on manipulation and rearrangement of the patient’s anatomy to promote malabsorption or create restrictive conditions in order to achieve weight loss. Instead, GES applies a small electric current to stimulate the stomach and induce early satiety while reducing appetite. Method An extensive literature search was performed using PubMed, Medline, Evidence-Based Medicine Reviews Multifile, Web of Science and CINHAL. The following keywords were searched individually and in combination: gastric electrical stimulation, gastric pacing, adult, obesity and weight loss. After reviewing 26 articles, three relevant articles were selected and then assessed in the final analysis. Conclusion Review of the evidence revealed that a small subset of obese adults treated with an implantable gastric stimulation device successfully achieved between 5% and 17% excess weight loss at the conclusion of the studies. However, this EWL range is similar to that achieved by diet and exercise alone in the SHAPE trial. Furthermore, some patients either failed to lose weight or gained weight after implantation with GES. Fortunately, the GES devices appear to be both safe to implement and well tolerated without any reported deaths and few serious adverse effects. Since the evidence implies some uncertainty about the benefits of implanting a gastric stimulation device for weight loss in obese individuals, it is suggested that clinicians continue to advise lifestyle changes, pharmacotherapy, or standard surgical approaches for weight loss. Discussion of Results The single randomized controlled trial (RCT), the SHAPE trial, is the first of its kind to explore, in a double-blind, placebo-controlled fashion, the applications of GES in obese subjects. Overall, the study was of excellent quality with only a small number of drawbacks. The major limitation of this study occurred at the conclusion of the 12 month trial period it was discovered that 22 participants had devices which read “low battery capacity.” All of these subjects were allocated to the treatment group which means that for an unspecified period of time some of the device batteries were exhausted. It is unknown whether these participants may have achieved greater weight loss had gastric stimulation been occurring as intended. The other two observational studies had small sample sizes, short study duration periods, and were open-label, non-randomized, and un-blinded studies. Furthermore, there is no proof of a large magnitude of effect, a dose-response relationship, or the identification of any confounders responsible for the treatment effect in either study. References Bohdjalian, A., Prager, G., Aviv, R., Policker, S., Schindler, K., Kretschmer, S.,... Ludvik, B. (2006). One-year experience with tantalus: A new surgical approach to treat morbid obesity. Obesity Surgery, 16(5), Centers for Disease Control and Prevention (CDC). (2010). Vital signs: State-specific obesity prevalence among adults --- United States, Morbidity & Mortality Weekly Report, 59(30), Champion, J. K., Williams, M., Champion, S., Gianos, J., & Carrasquilla, C. (2006). Implantable gastric stimulation to achieve weight loss in patients with a low body mass index: Early clinical trial results. Surgical Endoscopy, 20(3), Flegal, K. M., Carroll, M. D., Ogden, C. L., & Curtin, L. R. (2010). Prevalence and trends in obesity among US adults, Journal of the American Medical Association, 303(3), Hogan, A. M., Gallagher, T. K., Kennelly, R., Baird, A. W., & Winter, D. C. (2009). Gastric applications of electrical field stimulation. Surgical Laparoscopy, Endoscopy & Percutaneous Techniques, 19(2), Monash University. (2009). Obesity. Retrieved April 11, 2011, from Shikora, S. A., Bergenstal, R., Bessler, M., Brody, F., Foster, G., Frank, A.,... Sarwer, D. B. (2009). Implantable gastric stimulation for the treatment of clinically severe obesity: Results of the SHAPE trial. Surgery for Obesity & Related Diseases, 5(1), Acknowledgements: Justin Monell, Bill and Scotty Morris, Caitlin Morris, and Elks lodges across the country Purpose The purpose of this paper is to perform a systematic review of the most recent literature published after 2006, to evaluate the safety and efficacy of implantable gastric stimulation to reduce obesity in adult patients. The literature will be evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool developed by the GRADE Working Group. GRADE Table Discussion of GRADE The GRADE system, developed by the GRADE Working Group, rates both the quality of evidence and the strength of recommendation. Quality of evidence is classified as either high, moderate, low, or very low. Randomized controlled trials begin as high quality of evidence but can be downgraded whereas observational studies start as low quality of evidence but can be upgraded. A strong recommendation is made when it is very certain that the desirable effects of an intervention outweigh risks and burdens. A weak recommendation is given when risks and burdens are balanced against desired effects or when there is appreciable uncertainty about the magnitude of benefits and risks. After applying GRADE to the three articles evaluating weight loss in obese adult patients using gastric electrical stimulation, the GRADE for this outcome is moderate and the strength of the recommendation is weak. The poor study quality of the two observational studies combined with the existence of only one high quality RCT necessitates an overall GRADE of moderate for the body of evidence supporting the outcomes of weight loss via GES and GES device safety.