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

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.