Substance use disorders more likely in weight loss surgery patients, study finds

The death rate from drug- and alcohol-related causes in patients who have had gastric bypass surgery is nearly triple than the rate of the general public, according to new research from the University of Pittsburgh in Pennsylvania and published in the journal Surgery for Obesity and Related Diseases.

Over seven years, researchers followed 2,458 adults who underwent bariatric surgery. The participants were enrolled in the National Institutes of Health-funded Longitudinal Assessment of Bariatric Surgery-2 (LABS-2), a prospective, observational study of patients undergoing weight-loss surgery at one of 10 hospitals across the United States.

Reflecting typical bariatric surgery patients, the majority of study participants were female, 79 percent, and white, 86 percent. At time of surgery, the median age was 46 years old. During the seven-year follow-up, 10 of the participants died of causes directly related to drug- and alcohol-use, with six unintentional drug overdoses, one intentional overdose, one overdose where the intent was unknown, and two deaths from alcoholic liver disease. All 10 participants had undergone Roux-en-Y gastric bypass surgery, which reduces the size of the stomach and shortens the intestine, and accounted for 72 percent of the bariatric procedures in the study sample, according to the study abstract.

The team, led by Gretchen White, PhD, epidemiologist in the School of Medicine's Department of Surgery, looked at the deaths in terms of "person-years," a scientific measure that takes into account both the number of people in a study and the amount of time each person spends in the study. The drug- and alcohol-related death rate was 89 deaths per 100,000 person-years for the Roux-en-Y gastric bypass surgery patients, compared to 30.5 deaths per 100,000 person-years for the general population matched on age, sex, race and calendar year. On average, the deaths occurred nearly five years post-surgery.

While drug- and alcohol-related deaths were too rare to identify risk factors, the demographics of those who died were similar to the full sample. Based on demographics, bariatric surgery patients should be a low-risk group for substance-related death, according to senior author Wendy King, PhD, associate professor in the Graduate School of Public Health's Department of Epidemiology.

"Laboratory studies indicate that Roux-en-Y gastric bypass changes the way the body reacts to alcohol and drugs, and our previous work demonstrates an increased risk of self-reported problematic alcohol use and illicit drug use following this surgery,” said King in a statement released by the university. “This study indicates such problems can lead to loss of life."

The study also found that fewer than half of those who died had triggered a safety protocol for problematic substance use. Only one of those who died was known to have received treatment for substance use disorder.

"Increasingly with bariatric surgery patients, we're finding that the tools that clinicians traditionally use to screen for drug or alcohol problems don't work well to identify those at risk," said White in a statement released by the university. "These deaths are an extreme and sad example of a problem that needs to be addressed."

In addition to research to better understand the reasons for the high death rate, the researchets suggest that new clinical screening tools, tailored specifically to bariatric surgery patients, are needed so clinicians can better detect patients at high risk for substance use problems.

White said current questionnaires ask people about the number and frequency of alcoholic beverages they consume. Because bariatric surgery patients tend to experience the effects of alcohol faster and with fewer drinks than the average person, it might be better to ask about how alcohol makes them feel, if it is interfering with daily activities and whether they or their families and friends think they may have a problem.

Primary care physicians must be aware of the particular risks that bariatric surgery patients face in terms of substance use, the researchers said. However, further study is required to understand the precise mechanisms.