BARIATRIC SURGERY & SUICIDE: RESULTS FROM TWO CONTROLLED MATCHED COHORT STUDIES

BACKGROUND: Bariatric surgery reduces mortality, but may have adverse effects on mental health. We assessed suicide risk after surgical compared to nonsurgical obesity treatment. METHODS: Suicide and nonfatal self-harm events retrieved from nationwide Swedish registers were examined in two cohorts. The nonrandomised prospective Swedish Obese Subjects (SOS) study compares bariatric surgery (n=2010; 1369 vertical-banded gastroplasty, 376 gastric banding, 265 gastric bypass) with usual care (n=2037; recruitment 1987–2001). The second cohort comprises individuals from the Scandinavian Obesity Surgery Registry (SOReg; n=20,256 gastric bypass patients) matched to individuals treated with intensive lifestyle modification (n=16,162; intervention 2006–2013) on baseline BMI, age, sex, education level, diabetes, cardiovascular disease, history of self-harm, substance abuse, antidepressant use, anxiolytics use, and psychiatric healthcare contacts. FINDINGS: During 68,528 person-years (median 18; interquartile range 14–21) in SOS, there were 87 versus 49 suicides or nonfatal self-harm events in the surgery and control groups (adjusted hazard ratio [aHR] 1.78 [95%CI 1.23–2.57]; P=0.0021), of which 9 and 3 were suicides (3.06 [0.79–11.9]; P=0.107). In analyses by primary procedure type, increased risk of suicide or nonfatal self-harm was observed for gastric bypass (aHR 3.48 *1.65–7.31+; P=0.0010), gastric banding (2.43 *1.23–4.82+; P=0.011) and vertical-banded gastroplasty compared to controls (2.25 *1.37–3.71+; P=0.0015). Out of 9 deaths by suicide in the SOS surgery group, 5 occurred after gastric bypass (2 primary and 3 converted procedures). During 149,582 person-years (median 3.9; interquartile range 2.8–5.2), there were 341 suicides or nonfatal self-harm events in the SOReg gastric bypass group and 84 in the intensive lifestyle group (aHR 3.16 [2.46–4.06]; P<0.0001), of which 33 and 5 were suicides (5.17 [1.86–14.4]; P=0.0017). In SOS, substance abuse was recorded in 48% (39/81) of surgery patients and 28% (13/47) of controls with nonfatal self-harm events (P=0.023). The corresponding percentages for SOReg gastric bypass and intensive lifestyle participants were 51% (162/316) versus 29% (23/80; P=0.0003). INTERPRETATION: Bariatric surgery was associated with suicide and nonfatal self-harm. Although the absolute risks were low, the findings indicate a need for post-operative psychiatric surveillance and patient information before surgery regarding self-harm. FUNDING: US National Institutes of Health and Swedish Research Council