Patients who undergo gastric bypass surgery may be at a higher risk of death from drug- and alcohol-related causes, according to a new study by University of Pittsburgh researchers.

The study was published Friday in the journal Surgery for Obesity and Related Diseases. Here are the highlights:

The context

The scientists followed 2,458 adult bariatric surgery patients at 10 hospitals who had the procedure between 2006 and 2009. Seventy-nine percent of the group were women and 86 percent were white. Their median age at the time of the surgery was 46 years.

Seven years later, the researchers compared drug- and alcohol-related deaths among patients who underwent gastric bypass surgery in the U.S. with those of the general population, adjusting for factors including age, sex, and race.

While previous studies have looked at other causes of deaths in those who’d had bariatric surgery, this was the first paper to focus on drug and alcohol deaths, said Wendy King, associate professor of epidemiology at the University of Pittsburgh Graduate School of Public Health.

The surgery, called Roux-en-Y gastric bypass (RYGB), is a procedure that reduces the size of the stomach and shortens the intestine and therefore can change the way the body reacts to drugs and alcohol, King said.

Among the bariatric patients studied, 72 percent underwent the RYGB procedure.

Most of the participants had both a pre-surgery assessment and annual follow-ups for seven years.

The results

Researchers found that there were 10 deaths related to alcohol or drug use in the population studied. All 10 of those who died had RYGB.

The 10 deaths related to alcohol or drug use among those who underwent RYGB represented a rate nearly triple that of the general population, researchers found.

Of those who died, six were listed as unintentional drug overdoses, one was an intentional overdose, the intent of one overdose was unknown and two of the deaths were related to alcoholic liver disease, researchers found.

The deaths occurred about five years after the surgery and occurred in people who had not been considered at high risk for a substance-related death.

King said any physician with a patient that has undergone RYGB should be asking about alcohol and drug use as well as any symptoms related to alcohol-related problems, such as memory lapses, difficulty carrying out responsibilities, or needing alcohol to get going.

The caveats

The study used information from death certificates, which rely on the determinations of others, and focused only on those deaths directly attributed to drug or alcohol use.

The researchers did not have any data on the participants’ drug use and prescription drug use and if that contributed to the deaths, said King. Participants may have intentionally underreported their drug and alcohol use.

Next steps

The authors suggest looking more closely at patients’ mental health and substance use before and after bariatric surgery.

“This study adds another layer of showing the importance of post-operative care,” said King. The deaths happened years after the surgery, she said. “It is more of a long-term problem.”