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Medication Confers Additional Weight Loss After Bariatric Surgery in Young Adults

Key findings

  • Patients 21 to 30 years of age who were treated with topiramate, phentermine or metformin after bariatric surgery achieved median additional weight loss of 5.1% (5.8 kg)
  • Medication was beneficial after both Roux-en-Y gastric bypass and sleeve gastrectomy
  • Patients who took metformin after bariatric surgery had a significantly lower percentage of weight loss than other patients, possibly because of underlying medical conditions

After bariatric surgery, patients often struggle with inadequate weight loss or weight regain, and obesity-related comorbidities may return. Revision is only a feasible option if there are anatomic abnormalities, and the risk of complications is significantly higher with revision than with initial bariatric surgery, so researchers are exploring the use of medication as adjuvant therapy.

The response to some types of drugs, such as those for cardiovascular and psychiatric conditions, can vary according to the age of the patient. Fatima Cody Stanford, MD, MPH, MPA, an obesity medicine physician for adults, adolescents and children at the Massachusetts General Hospital Weight Center, and colleagues have published reassuring evidence in Children that adults 30 years of age and younger respond equally as well to medical therapy as older adults.

Study Participants

Dr. Stanford's team evaluated 37 patients who met the eligibility criteria from two academic medical centers on 5,110 patients who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy between November 2000 and June 2014. Criteria included:

  • Age 30 years or younger at the time of surgery (range in age from 21 to 30)
  • Subsequently placed on topiramate, phentermine or metformin
  • Had at least 12 months of follow-up
  • Did not have surgery for complications within six months of the initial surgery
  • Did not require revision surgery

Of these participants, 28 underwent RYGB and nine underwent sleeve gastrectomy. Altogether, 65% identified as white, 19% as Hispanic and 13.5% as African-American.

With surgery, all but four patients lost more than 20% of their body weight, a metric often used as the definition of successful metabolic and bariatric surgery.

Amount of Additional Weight Loss

The addition of medication to treatment proved beneficial for the majority of participants, helping 20 patients (54%) lose ≥5% of their postsurgical weight. They were all high responders: 12 patients (34.5%) lost ≥10% of their postsurgical weight, and eight (23%) lost ≥15%.

These results were similar to those from a previous study led by Dr. Stanford, which reviewed 319 patients between the ages of 21 and 73. All told, 56%, 30% and 16% of patients in that study achieved ≥5%, ≥10%, and ≥15% additional weight loss, respectively.

Patients in the RYGB group lost more of their postsurgical weight on medications (8.1%) than patients who underwent sleeve gastrectomy (3.3%), and the difference approached statistical significance (P = .0515). However, weight loss was at a beneficial level for both groups.

Results of Individual Agents

Patients who took metformin after bariatric surgery had a significantly lower percentage of weight loss (2.9%) compared with the rest of the study cohort (7.7%) (P = .02). There was no significant difference in weight loss percentage with topiramate or phentermine when patients on those drugs were compared with the rest of the cohort.

The researchers find it likely that metformin was associated with less weight loss because the medical conditions it is used to treat (such as insulin resistance, type 2 diabetes and metabolic syndrome) can make weight loss more difficult. They believe this finding needs further research and is not an indictment of metformin as adjuvant treatment after bariatric surgery.

54%
of patients lost ≥5% of their postsurgical weight with the addition of medication

34.5%
of patients lost ≥10% of their postsurgical weight with the addition of medication

23%
of patients lost ≥15% of their postsurgical weight with the addition of medication

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