Prospective study of psychiatric illness as a predictor of weight loss and health related quality of life one year after bariatric surgery

Objective: Despite a lack of evidence, there is an assumption that patients with more complex psychiatric histories (CPH) prior to bariatric surgery have poor post-surgical weight loss and worsening psychiatric symptoms following surgery. Consequently, those with CPH are excluded from bariatric surgery in many bariatric clinics. This study examines whether psychiatric illness affects post-surgical weight loss and HRQOL, focusing on patients with CPH.

Method: This prospective cohort study investigated 341 patients from a tertiary care centre bariatric surgery program who had surgery between September 2010 and October 2013. Patients were divided into CPH, other psychiatric disorder (OPD), or no psychiatric disorder (NPD) groups based on lifetime psychiatric diagnoses. Groups were compared one year post-surgery in regards to percent total weight loss (%TWL), mental and physical health related quality of life (HRQOL) using a Kruskal-Wallist test. Linear regression analysis was used to determine if mental illness group, gender, age, pre-op BMI, education, employment and relationship status predict change in %TWL and HRQOL.

Results: There was no significant difference in %TWL or physical HRQOL across groups. The CPH group experienced a decrease in mental HRQOL (p=0.0003). Mental illness severity predicted mental HRQOL (p=0.002) but not physical HRQOL or %TWL.

Conclusion: Those with controlled CPH can achieve comparable weight loss compared to those with OPD or NPD. However, CPH may predict post-surgical decline in mental HRQOL. These findings demonstrate a need to reevaluate exclusion criteria to ensure equitable access to care, while continuing to monitor for psychiatric illness following surgery.