SILVER SPRING, Md.--Researchers have discovered that anti-obesity medications such as phentermine and topiramate, used individually or in combination, can significantly reduce weight regain in patients after Roux-en-Y gastric bypass surgery, according to a retrospective study published online in Obesity, the flagship journal of The Obesity Society.
"Our study provides evidence that medications can help, especially in situations where the weight gain is occurring at a rapid rate. Characterization of weight regain as a rate is novel and adds to the understanding of this important clinical problem," said Nawfal Istfan, MD, PhD, associate professor of medicine at Boston University School of Medicine and attending physician at Boston Medical Center in Boston, Mass. Istfan is the corresponding author of the study.
Weight regain after gastric bypass surgery is well recognized, normally occurring two years after the surgery and ultimately affecting 25 percent of patients. It is becoming increasingly urgent to mitigate its occurrence and preserve the metabolic and medical benefits of weight loss surgery. The application of pharmacologic agents to deal with this specific problem has been limited in the medical literature.
Researchers used the electronic medical records of nearly 1,200 multi-ethnic patients who underwent Roux-en-Y gastric bypass surgery between 2004 and 2015 at Boston Medical Center. The evaluation of weight regain was made by comparing each patient's weight during subsequent, post-operative office visits to nadir weight (lowest weight after Roux-en-Y gastric bypass surgery), taking into consideration the interval during which weight regain occurred. Seven time intervals were used in the analysis ranging from before surgery to 6 years after surgery. Patients prescribed anti-obesity medications and who came for follow-up visits were classified as adherent users, whereas those who missed follow-up visits were considered non-adherent.
After using three independent statistical models, researchers demonstrated that anti-obesity medications decrease cumulative weight regain by about 10 percent relative to nadir weight and reduce the odds of rapid weight-regain occurrence after Roux-en-Y gastric bypass surgery. Researchers also found that of the 760 patients who achieved nadir weight and are at risk for weight regain, 350 were documented users of anti-obesity medications.
These results take into account that patients typically lost weight when taking anti-obesity medications and regained weight during intervals when the medications were not prescribed. Additionally, patients started anti-obesity medications at different stages and used them at variable and intermittent periods.
The authors noted that the full potential of phentermine and topiramate and newer anti-obesity medications to counter weight recidivism and prevent the reoccurrence of obesity-related comorbidities need to be explored in further prospective clinical trials. Guidelines also need to be established for initiating and monitoring the potential long-term use of anti-obesity medications after bariatric surgery.
"One of the ways to address this particular set of limitations in future study with a prospective clinical trial would be to set specific protocols regarding use of anti-obesity medications by providers. Specifically, providing education for providers on individual anti-obesity medications for them to understand mechanisms of action, then separately creating a clinical workflow to incorporate use of anti-obesity medications, in particular settings of weight recidivism," said Crystal Johnson-Mann, MD, assistant professor, Department of Surgery, Division of Gastrointestinal Surgery, at the University of Florida College of Medicine in Gainesville. "For optimal results in a prospective trial, individual prescribing tendencies (or lack of prescribing) needs to be eliminated and be uniform across all of the providers involved in the care of these patients post-operatively."
Other authors of the study include Wendy Anderson, Donald Hess and Brian Carmine of the Section of Minimally Invasive Surgery, Department of Surgery, School of Medicine at Boston University/Boston Medical Center; and Liqun Yu and Caroline Apovian of the Section of Endocrinology, Diabetes, Nutrition and Weight Management, Department of Medicine, School of Medicine, Boston University/Boston Medical Center in Boston, Mass.
This work was supported in part by the National Institutes of Health (P30DK046200).
The study, titled "The Mitigating Effect of Phentermine and Topiramate on Weight Regain after Roux-en-Y Gastric Bypass Surgery" will be published in the June 2020 print issue.
The Obesity Society (TOS) is the leading organization of scientists and health professionals devoted to understanding and reversing the epidemic of obesity and its adverse health, economic and societal effects. Combining the perspective of researchers, clinicians, policymakers and patients, TOS promotes innovative research, education, and evidence-based clinical care to improve the health and well-being of all people with obesity. For more information, visit http://www.