The prognostic significance of depressive symptoms for predicting quality of life 12 months after gastric bypass.

OBJECTIVE: This study was conducted to examine the relative prognostic significance of weight and depressive symptoms for 12-month postoperative health-related quality of life (HRQL) in extremely obese gastric bypass patients.
METHODS: Participants comprised 137 extremely obese patients undergoing gastric bypass surgery. Presurgery and 12 months postsurgery participants completed the Medical Outcomes Study Short Form-36 Health Survey, a standard measure of HRQL, and the Beck Depression Inventory (BDI). Regression analyses were performed to predict HRQL, both before and 12 months after surgery, by using demographic variables, and measures of body mass index (BMI) and depressive symptoms as predictors.
RESULTS: At baseline the predictors accounted for 19% of the variance of physical HRQL, and 56% of the variance of mental HRQL. At 12 months after surgery, the predictors accounted for 32% of the variance of physical HRQL and 48% of mental HRQL. In the prediction of 12-month postoperative HRQL, baseline BMI, BMI unit change, baseline BDI, and improvements in BDI score made significant contributions to most of the Medical Outcomes Study Short Form-36 Health Survey scales. Demography contributed little to these predictor analyses. Depressive symptoms made greater contributions than weight and demography, and change in BDI score made the greatest contributions (ranging from 3% to 37%) of all the variables tested.
CONCLUSIONS: Measures of weight and depressive symptoms were useful in predicting quality of life both before and 12 months after gastric bypass surgery; however, this is the first study to document that improvements in HRQL postsurgery may be largely related to improved depressive symptoms.