Long-term risk of clinical depression and anxiety after bariatric surgery: a population-based matched cohort study

Abstract Background Bariatric surgery is an effective treatment for severe obesity and its physical complications, but its long-term impact on mental health is uncertain. Evidence on the risks of clinical depression and anxiety after surgery remains limited. Methods We conducted a population-based matched cohort study using data from the UK Clinical Practice Research Datalink (CPRD) Aurum between January 1, 2000, and January 31, 2022. Adults aged 18 years or older with severe obesity (body mass index [BMI] ≥ 35 kg/m²) and no previous diagnosis of depression or anxiety were included. 7,814 patients who underwent bariatric surgery (gastric bypass, sleeve gastrectomy, or gastric banding) were matched (1:5) by age, sex, BMI, and index year to 36,941 patients receiving behavioural weight management. Incident depression and anxiety were identified from diagnostic, referral, or prescription records. Multivariable Cox proportional hazards models estimated hazard ratios (HRs) and 95% CIs, adjusted for demographic, clinical, and socioeconomic factors. Results This study included 44,755 participants with a median follow-up of 4.8 years (interquartile range, 2.3–8.8 years). During 15 years of follow-up, 23.1% of patients in the surgery group and 17.4% in the control group developed depression, and 9.0% vs. 7.1% developed anxiety, respectively. In fully adjusted models, bariatric surgery was associated with higher risks of incident depression (HR, 1.36 [95% CI, 1.28–1.45]) and anxiety (HR, 1.31 [95% CI, 1.19–1.44]). In subgroup analyses, bariatric surgery was associated with increased risks of depression across BMI categories and with depression and anxiety across procedure types. No evidence of interaction was observed by age or sex. The findings were robust in sensitivity analyses. Conclusions Bariatric surgery was associated with increased long-term risks of depression and anxiety compared with behavioural weight management. These findings support ongoing monitoring of mental health as part of long-term follow-up after bariatric surgery.