By Melinda Beck
October 7, 2015

People who undergo surgery for weight loss are 50% more likely to attempt suicide after the operation than before it, according to a large Canadian study published Wednesday in the journal JAMA Surgery.

The popular procedures, which were performed nearly 200,000 times in the U.S. last year, result in significant weight loss for most patients and often bring about reductions in Type 2 diabetes, hypertension and sleep apnea as well. Many patients also report improved mood and self-esteem. But a small group experience a worsening of depression, substance abuse and eating disorders, past studies have found.

Earlier studies have also noted that suicides are several times more common among bariatric-surgery patients than in the general population, but whether that was due to the operation or high rates of mental-health issues associated with obesity hasn’t been clear. 

The new study, from the Sunnybrook Research Institute at the University of Toronto, addressed that issue by comparing suicide attempts in the same group of patients, before and after surgery.

The researchers studied hospital records for 8,815 Ontario residents who had bariatric surgery between 2006 and 2011 for three years before and after the procedures. Of the group, 111 were treated for 158 “self-harm emergencies” at hospitals during those years. One-third of those suicide attempts occurred before the patients had the surgery; two-thirds occurred afterward. Overall, the rate of self-harm attempts was 2.3 per 1,000 before the surgery and 3.6 per 1,000 afterward, compared with fewer than 1 per 1,000 in the general population. 

The study wasn’t able to capture data on completed suicide attempts or incidents in which patients weren’t treated at hospitals, so the authors said it likely underestimated the true rate of suicide attempts.

The researchers were also unable to determine whether the patients who harmed themselves had regained lost weight, or were struggling with other issues. Almost all who attempted suicide had been diagnosed with major depression before the surgery.

Most of the attempts occurred between two and three years after the surgery, which the authors said underscored the need for longer follow-up counseling. “We have to acknowledge that that is a life-changing procedure. Patients have to adapt to a new lifestyle, which can be stressful for them,” said Junaid Bhatti, an epidemiologist at Sunnybrook and the study’s lead researcher.

The procedures, which either reduce the stomach’s capacity to hold food, or bypass part of the intestines to limit absorption, do require patients to change their eating habits substantially. Some experts say vulnerable patients may substitute alcohol or other substances for food. Some studies suggest that rerouting the digestive tract affects the level of hormones and neurotransmitters in the gut that regulate mood as well as appetite and satiety. Even patients who do lose weight may have outsize expectations for how much their lives will improve as a result.

“It’s often in the second and third year when the disappointment sets in, and in most cases, the follow-up has stopped,” said Donald Redelmeier, a professor of medicine at the University of Toronto and a co-author of the study. “At that point, people often think there is nothing else they can do, and they give up hope. That’s what we’re trying to avoid.” 

John Morton, president of the American Society for Metabolic and Bariatric Surgery said the organization does require the hospitals it credentials to provide mental-health screening and counseling for up to five years after the surgery. Still, Dr. Morton, who wasn’t involved in the study, said it “reflects the burden of disease that our obese patients live with for a long time, and while it’s alleviated by weight-loss surgery, it may not be completed eradicated for some people.”