Bariatric surgery increases risk of depression and self-harm

Gastric bypass surgery is used to help obese patients lose weight, but a study from Karolinska Institutet published in the Annals of Surgery shows that people with a history of depression run a high risk of severe post-operative depression.

Gastric bypass, or bariatric surgery, is used around the world to help seriously obese patients lose weight, reducing their chances of diabetes and improving the quality of their lives. However, there has also been some debate on whether it can have adverse psychiatric consequences. In the present study, the researchers examined the frequency of hospitalisation for depression, self-harm and suicide after gastric bypass surgery using data from the Swedish National Patient Register, the Swedish Prescribed Drug Register and the Cause of Death Registry.

"Our results show that people with a previous diagnosis of depression up to two years prior to surgery were 52 times more likely to become so depressed that they required inpatient psychiatric care in the two years following surgery," says Ylva Trolle Lagerros, Associate Professor at the Department of Medicine, Solna. "People without a depression diagnosis, but who had been prescribed antidepressants at least once ran an eight times higher risk of such severe depression."

Patients with a self-harm diagnosis prior to surgery were 36 times more likely to repeat their self-harming behaviour afterwards. This risk was highest in the under-25 group and declined with age.

Amongst women the risk of suicide was 4.5 times higher than Swedish women of the same age.

To conduct their study, the team studied registry data for everyone – 22,539 people in total – who had undergone bariatric surgery in Sweden between the years of 2008 and 2012. The average age was 41.3 years and 75.3 per cent were women. The number of patients who had been diagnosed with self-harm or depression or who had been prescribed antidepressants up to two years before surgery was noted, and the risk of hospitalisation for depression or self-harm during the two years following surgery was then calculated. As regards suicide, the risk for bariatric surgery patients was compared with that for the Swedish population of the same sex and age over the two years following surgery.

"Our results show that we need more awareness of the psychiatric risks facing this patient group," says Dr Trolle Lagerros. "These are alarming figures and they therefore should be offered extra post-operative psychiatric support. But it would be wrong to say that this patient group should be denied the possibility of receiving surgery for their obesity."