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/m(2) (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 (<50% excess weight loss) and not following up with their appointment compared with those who scored below cut-offs.

Conclusions: Patients who are more likely to engage in undercontrolled behavior (e.g., poor impulse control), as indicated by presurgical MMPI-2-RF findings, are at greater risk for suboptimal weight loss and poor adherence to follow-up following RYGB. Objective psychological assessments should also be conducted postoperatively to ensure that intervention is administered in a timely manner. Future research in the area of presurgical psychological screening should consider the impact of underreporting and other discussed methodologic issues in predictive analyses.

Keywords: Adherence; Assessment; Bariatric surgery; Incremental validity; MMPI-2-RF; Obesity; Outcome; Psychology; Roux-en-Y; Underreporting; Weight loss.