The Mitigating Effect of Phentermine and Topiramate on Weight Regain After Roux-en-Y Gastric Bypass Surgery.

OBJECTIVE: Weight regain (WR) after Roux-en-Y gastric bypass surgery (RYGB) starts to occur 2 years after surgery, ultimately affecting at least 25% of patients. A limited number of studies have evaluated the impact of antiobesity medications (AOMs) on this phenomenon. METHODS: This study reviewed the electronic medical records of 1,196 patients who underwent RYGB between 2004 and 2015. WR was evaluated by comparing each patient's weight during subsequent postoperative office visits to nadir weight (lowest weight after RYGB, n = 760), taking into consideration the interval during which WR occurred. Patients who were prescribed AOMs and came to follow-up visits were classified as adherent users, whereas those who missed their follow-up visits were considered nonadherent. This study used a linear mixed model, Cox regression, and generalized equation estimator to determine the impact of AOMs on WR trajectory, hazard ratio for time to event, and odds ratio for repeated event occurrence, respectively. RESULTS: Despite the lack of a unified protocol for using AOMs, the three statistical models converged to show that phentermine and topiramate, used individually or in combination, can significantly reduce WR after RYGB. CONCLUSIONS: Phentermine and topiramate are effective in mitigating WR after RYGB. Further studies are needed to help ascertain optimal use of AOMs after bariatric surgery.