Psychiatric Morbidity After Bariatric Surgery and its Association with Postoperative Body Mass Index: A National Analysis

Background:Metabolic and bariatric surgery (MBS) remains the most effective intervention for durable weight loss and improvement of obesity-related comorbidities.However, its association with psychiatric morbidity remains unclear. Objectives:To evaluate the association between prior MBS status and psychiatric morbidity at a national level and to identify any contributing factors. Setting:National Inpatient Sample, the largest publicly available all-payer inpatient database in the United States. Methods:A retrospective cohort analysis was conducted using data from 2016-2021.Adult encounters (18 years) with documented BMI were included and stratified by prior MBS status.Following entropy balancing to minimize baseline differences, multivariable models were used to evaluate the independent cross-sectional association between prior MBS status and psychiatric morbidity odds. Results:Among 32,879,950 encounters, 831,285 (2.5%) involved patients with prior MBS.After entropy balancing and risk adjustment, prior MBS status was independently associated with increased odds of depression (AOR, 1.70; 95% CI, 1.68-1.72),bipolar disorder (AOR, 1.52; 95% CI, 1.48-1.56),anxiety (AOR, 1.49; 95% CI, 1.47-1.51),and eating disorders (AOR, 1.34; 95% CI, 1.20-1.51),but not with suicidal ideation and attempt (AOR, 1.00; 95% CI, 0.95-1.06;p = .99).Within the MBS cohort, lower postoperative J o u r n a l P r e -p r o o f BMI was progressively associated with higher odds of psychiatric morbidity (p < .001for trend). Conclusions:Prior MBS status is associated with increased odds of psychiatric morbidity, particularly among patients with lower postoperative BMI.While causality cannot be inferred, these findings highlight the need for integrated mental health screening and longitudinal psychiatric support throughout the perioperative continuum.