AT OBESITY WEEK 2016

NEW ORLEANS (FRONTLINE MEDICAL NEWS) – Severely obese patients who undergo Roux-en-Y gastric bypass surgery are subsequently at sharply increased risk for new-onset alcohol use disorder as well as for treatment of substance use disorder, compared with others who opt for a laparoscopic adjustable banding procedure for weight loss, Wendy C. King, PhD, reported at a meeting presented by the Obesity Society of America and the American Society for Metabolic and Bariatric Surgery.

This new finding from the NIH-sponsored Longitudinal Assessment of Bariatric Surgery–2 study (LABS-2) has important implications for clinical practice.

“Patients considering bariatric surgery really should be informed of this surgery-specific risk. Also, alcohol use disorder screening, evaluation, intervention, and referral should be incorporated as part of regular presurgical and definitely also postoperative care. And because many patients don’t return to their surgeon for long-term postoperative care, it’s important that clinicians in primary care and other specialties are really looking for this problem in long-term follow-up,” said Dr. King , an epidemiologist at the University of Pittsburgh.

LABS-2 is an observational cohort study of patients undergoing first-time bariatric surgery at 10 participating U.S. hospitals, all of which have academic ties and are rated as bariatric surgery centers of excellence. Dr. King presented 5-year postsurgical follow-up data on 1,481 patients who had Roux-en-Y gastric bypass (RYGB) and 522 with laparoscopic adjustable gastric banding (LAGB). Independently of their regular clinical care visits, participants were assessed annually for their alcohol use and its consequences using the Alcohol Use Disorders Identification Test (AUDIT), use of illicit drugs within the past year, and whether they had undergone hospitalization or counseling for alcohol or drug problems. A score of 8 or more points on the AUDIT was deemed an indication of symptoms of alcohol use disorder (AUD),

After eliminating from consideration the 7% of patients with AUD symptoms at baseline, the cumulative incidence of AUD symptoms in the RYGB patients climbed from zero to 20.8% by the end of the fifth year of follow-up. Treatment for a substance use disorder occurred in 3.5% of RYGB patients during their first 5 years postsurgery, and 7.5% admitted to illicit drug use, said Dr. King.

In contrast, the cumulative incidence of AUD symptoms through 5 years in the LAGB patients was only 11.3%, less than 1% underwent treatment for a substance use disorder, and 4.9% said they had used illicit drugs.

But LABS-2 is not a randomized trial. Patients chose their bariatric procedure together with their surgeon. For this reason, it was important to perform a multivariate regression analysis adjusted for sociodemographics, social support, psychiatric treatment, lifetime history of psychiatric hospitalization, baseline smoking and alcohol consumption, and other potential confounders.

After performing this statistical exercise, the RYGB patients remained at an adjusted 2.05-fold increased risk of AUD symptoms, compared with the LAGB patients, as well as at 3.83-fold greater risk of treatment for a substance use disorder.

The 1.6-fold increased rate of illicit drug use in the RYGB group didn’t achieve statistical significance. Moreover, on closer examination, most of this illicit drug use involved marijuana, and its use in the post–bariatric surgery population appeared to mirror secular trends in the United States as a whole, according to Dr. King.

With her coinvestigators, Dr. King searched for presurgical risk factors that might predict postsurgical substance misuse. Perhaps the most interesting finding concerned the factors that weren’t predictive, including education, unemployment, score on the Beck Depression Inventory, SF-36 mental component summary score, race, marital status, binge eating, loss of control eating, and body mass index.

Lower social support prior to surgery was associated with increased risk for developing AUD symptoms during the first 5 years after bariatric surgery. Younger age and smoking at baseline were associated with increased rates of postoperative AUD symptoms, substance use disorder treatment, and illicit drug use. A history of psychiatric treatment was associated with increased rates of substance use disorder treatment and illicit drug use.

“That could indicate greater medical surveillance among those patients or greater willingness to get treatment, since they’d had treatment for other psychiatric issues in the past,” Dr. King speculated.

She described the study’s strengths as its large size, geographically diverse patient population, unusually high retention over time, compared with other bariatric surgery studies, and the use of AUDIT, a validated and reliable screening tool. The major limitations are that investigators didn’t inquire about illicit use of opioids and benzodiazepines, and recipients of gastric sleeve procedures weren’t included in the long-term follow-up analysis because LABS-2 began before the gastric sleeve boomed in popularity.

John M. Morton, MD , a former president of the American Society for Metabolic and Bariatric Surgery, predicted that a similar study that included gastric sleeve patients would show them to have the same unremarkable postoperative rates of substance misuse as the LAGB group.

“I want to emphasize that this increased incidence of alcohol problems in the Roux-en-Y gastric bypass patients is maybe not so much a psychological issue as it is a physiologic one,” added Dr. Morton, chief of bariatric and minimally invasive surgery at Stanford (Calif.) School of Medicine.

Dr. King agreed. “Just in the last year and a half there have been some great pharmacokinetic studies showing that the Roux-en-Y affects alcohol metabolism and absorption, as well as studies in rodent models that suggest alcohol produces increased neurobiologic reward,” she noted.

The LABS-2 study is funded by the National Institute of Diabetes and Digestive and Kidney Diseases. Dr. King reported having no relevant financial interests.

bjancin@frontlinemedcom.com

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