Anti-obesity drugs may help maintain weight loss after bariatric surgery

SILVER SPRING, Md.--Weight regain after gastric bypass surgery is well recognized, normally occurring two years after the surgery and ultimately affecting 25 percent of patients. Various measures for maintaining the weight loss need to be explored and adopted.

Researchers have found in a retrospective study 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 study has been published online in the journal Obesity.

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.

"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.

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."