Boston University School of Medicine 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. The retrospective study paper, 'The Mitigating Effect of Phentermine and Topiramate on Weight Regain after Roux-en-Y Gastric Bypass Surgery', was published in Obesity.
"Our study provides evidence that medications can help, especially in situations where the weight gain is occurring at a rapid rate,” said Dr Nawfal Istfan, corresponding author of the study, associate professor of medicine at Boston University School of Medicine and attending physician at Boston Medical Center in Boston, MA. “Characterisation of weight regain as a rate is novel and adds to the understanding of this important clinical problem.”
Weight regain after gastric bypass surgery is well recognised, normally occurring two years after the surgery and affecting approximately 25 percent of patients. It is becoming increasingly urgent to mitigate its occurrence and preserve the metabolic and medical benefits of bariatric 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 six 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 Dr Crystal Johnson-Mann, 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."