Using presurgical psychological testing to predict 1-year appointment adherence and weight loss in bariatric surgery patients: predictive validity and methodological considerations

Abstract Background Previous studies suggest that presurgical psychopathology accounts for some of the variance in suboptimal weight loss outcomes among Roux-en-Y gastric bypass (RYGB) patients, but research has been equivocal. Objectives The present study seeks to extend the past literature by examining associations between presurgical scale scores on the broadband Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF) and suboptimal weight loss and poor adherence to follow-up 1 year postoperatively after accounting for several methodologic considerations. Setting Cleveland Clinic Bariatric and Metabolic Institute, Cleveland, Ohio, USA. Methods The sample consisted of 498 RYGB patients, who produced a valid presurgical MMPI-2-RF protocol at program intake. The sample was primarily female (72.9%), Caucasian (64.9%), and middle-aged (mean = 46.4 years old; standard deviation [SD] = 11.6). The mean presurgical body mass index (BMI) was 47.4 kg/m2 (SD = 8.2) and mean percent weight loss (%WL) at 1 year postoperatively was 31.18 %WL (SD = 8.44). Results As expected, scales from the Behavioral/Externalizing Dysfunction (BXD) domain of the MMPI-2-RF were associated with worse weight loss outcomes and poor adherence to follow-up, particularly after accounting for range restriction due to underreporting. Individuals producing elevated scores on these scales were at greater risk for achieving suboptimal weight loss (