Risk of suicide and non-fatal self-harm after bariatric surgery: results from two matched cohort studies

Abstract

Background: Bariatric surgery reduces mortality, but might have adverse effects on mental health. We assessed the risk of suicide and self-harm after bariatric surgery compared with non-surgical obesity treatment.

Methods: Suicide and non-fatal self-harm events retrieved from nationwide Swedish registers were examined in two cohorts. The non-randomised, prospective Swedish Obese Subjects (SOS) study compared bariatric surgery (n=2010; 1369 vertical-banded gastroplasty, 376 gastric banding, and 265 gastric bypass) with usual care (n=2037; recruitment 1987-2001). The second cohort consisted of individuals from the Scandinavian Obesity Surgery Registry (SOReg; n=20 256 patients who had gastric bypass) matched to individuals treated with intensive lifestyle modification (n=16 162; intervention 2006-13) on baseline BMI, age, sex, education level, diabetes, cardiovascular disease, history of self-harm, substance misuse, antidepressant use, anxiolytics use, and psychiatric health-care contacts.

Findings: During 68 528 person-years (median 18; IQR 14-21) in the SOS study, suicides or non-fatal self-harm events were higher in the surgery group (n=87) than in the control group (n=49; adjusted hazard ratio [aHR] 1·78, 95% CI 1·23-2·57; p=0·0021); of these events, nine and three were suicides, respectively (3·06, 0·79-11·88; p=0·11). In analyses by primary procedure type, increased risk of suicide or non-fatal self-harm was identified for gastric bypass (3·48, 1·65-7·31; p=0·0010), gastric banding (2·43, 1·23-4·82; p=0·011), and vertical-banded gastroplasty (2·25, 1·37-3·71; p=0·0015) compared with controls. Out of nine deaths by suicide in the SOS surgery group, five occurred after gastric bypass (two primary and three converted procedures). During 149 582 person-years (median 3·9; IQR 2·8-5·2), more suicides or non-fatal self-harm events were reported in the SOReg gastric bypass group (n=341) than in the intensive lifestyle group (n=84; aHR 3·16, 2·46-4·06; p<0·0001); of these events, 33 and five were suicides, respectively (5·17, 1·86-14·37; p=0·0017). In SOS, substance misuse during follow-up was recorded in 48% (39/81) of patients treated with surgery and 28% (13/47) of controls with non-fatal self-harm events (p=0·023). Correspondingly, substance misuse during follow-up was recorded in 51% (162/316) of participants in the SOReg gastric bypass group and 29% (23/80) of participants in the intensive lifestyle group with non-fatal self-harm events (p=0·0003). The risk of suicide and self-harm was not associated with poor weight loss outcome.

Interpretation: Bariatric surgery was associated with suicide and non-fatal self-harm. However, the absolute risks were low and do not justify a general discouragement of bariatric surgery. The findings indicate a need for thorough preoperative psychiatric history assessment along with provision of information about increased risk of self-harm following surgery. Moreover, the findings call for postoperative surveillance with particular attention to mental health.

Funding: US National Institutes of Health and Swedish Research Council.

Figure 1. Cumulative incidence of suicide and nonfatal self-harm in the Swedish Obese Subjects (SOS) study

Hazard ratios adjusted for age, sex, BMI, and history of self-harm

Figure 2. Cumulative incidence of suicide and nonfatal self-harm in the Swedish Obese Subjects (SOS) study by primary procedure type

Case ascertainment from inpatient care and Causes of Death Register only as the outpatient care component was added in 2001 and gastric bypass was used more in the later part of the SOS recruitment period VBG=vertical-banded gastroplasty

Figure 3A. Suicide and nonfatal self-harm in the Swedish Obese Subjects (SOS) cohort overall and by subgroups

Adjusted for age, sex, BMI, and history of self-harm. Inpatient care only: Refers to case ascertainment excluding data from the outpatient component from the National Patient Register. Outpatient data were available from 2001 and onwards. Psychiatric history: Baseline characteristics for the subgroup with psychiatric history are provided in eTable5.

Figure 3B. Suicide and nonfatal self-harm in the SOReg/Itrim cohort overall and by subgroups

Matched on age, sex, BMI, education level, cardiovascular disease, diabetes, history of self-harm, substance abuse, visits in psychiatric care, use of antidepressants, and use of anxiolytics. Additional adjustment was made for age, BMI and income as continuous variables, as well as for marital status, disability pension, and unemployment status as binary variables. Incidence rates and hazard ratios are weighted by the strata size to account for the matching. Inpatient care only: Refers to case ascertainment excluding data from the outpatient component from the National Patient Register. Psychiatric history: Baseline characteristics for the subgroup with psychiatric history are provided in eTable5.

Figure 4. Weight development over 10 years in surgery patients in the SOS study by suicide and self-harm status (overall and by primary procedure type)

Adjustment variables were the same as in the main analysis (age, sex, baseline BMI, and history of self-harm)

Figure 5. Cumulative incidence of suicide and nonfatal self-harm in the SOReg/Itrim study comparing gastric bypass with intensive lifestyle modification

Matched on age, sex, BMI, education level, cardiovascular disease, diabetes, history of self-harm, substance abuse, visits in psychiatric care, use of antidepressants, and use of anxiolytics. Hazard ratios adjusted for age, BMI, income, marital status, disability pension, and unemployment N for intensive lifestyle group are weighted by the strata size to account for the matching