Association Between Preoperative Psychological Distress and Successful Weight Loss After Bariatric Surgery: A Retrospective Study

Objectives: The relationship between preoperative psychological distress and weight loss following bariatric surgery remains limited in Asian populations. This study aimed to investigate whether preoperative psychological distress, as a general screening measure, predicted weight loss following bariatric surgery in a Thai population. Methods: We conducted a retrospective cohort study of 464 patients who underwent bariatric surgery at a university hospital between 2020 and 2023. Preoperative psychological distress was assessed using the General Health Questionnaire-28 (GHQ-28), with a score of ≥6 indicating high psychological distress. The primary outcome was successful weight loss (SWL), defined as achieving >50% excess weight loss at 6 and 12 months postoperatively. We used multivariable logistic regression models, adjusted for age, sex, surgery type, obesity-related comorbidities, and baseline body weight, to analyze the association between psychological distress and SWL outcomes. Results: Patients with high psychological distress (n = 270) demonstrated significantly higher rates of SWL compared to those with low distress (n = 194) at both 6 months (59.7% vs. 43.5%, p = 0.003) and 12 months (83.6% vs. 74.6%, p = 0.068). In adjusted regression analyses, patients with high distress had approximately twice the odds of achieving SWL at 6 months (adj. OR 1.99, 95% CI: 1.25–3.17, p = 0.004), with this association persisting at 12 months (adj. OR 1.86, 95% CI: 1.02–3.39, p = 0.044). Subgroup analyses revealed consistent associations across both sexes, with no significant interaction effects. Conclusions: Contrary to traditional assumptions, higher preoperative psychological distress was associated with greater odds of achieving successful weight loss after bariatric surgery. This suggests that psychological distress may not be a barrier to successful outcomes but could, when supported appropriately, be a predictor for significant weight loss. These findings highlight the value of psychological assessment in optimizing, rather than restricting, bariatric surgery candidates.