Internalizing, Externalizing, and Interpersonal Components of the MMPI-2-RF in Predicting Weight Change After Bariatric Surgery

Background The Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF) is commonly used to assess psychological factors that may adversely impact weight loss. Research is limited on the specific MMPI-2-RF scales that may predict poor postoperative outcomes following bariatric surgery. The current study compared preoperative MMPI-2-RF profiles associated with postoperative weight change to novel component scores in a bariatric surgery sample. Methods One hundred twenty-seven patients completed a preoperative medical evaluation, a test of reading ability, and the MMPI-2-RF. Percent weight loss was obtained postoperatively at 6 and 12 months. Results Principal components analysis (PCA) generated five novel subcomponents from within the internalizing, externalizing, and interpersonal substantive scales of the MMPI-2-RF. Among these components, higher externalizing and social conflict scores at baseline were predictive of less percent weight change postoperatively at 6 months. A similar trend was observed with higher insecurity scores predicting less weight loss at 6 months postoperatively. At 12-month follow-up, higher insecurity scores at baseline remained predictive of lower percentage weight loss, while social conflict trended toward significance in the same direction. Model comparisons of traditional MMPI-2-RF scales were found to be more sensitive than the novel subcomponents. Specifically, demoralization (RCd), antisocial behavior (RC4), hypomanic activation (RC9), family problems (FML), and shyness (SHY) significantly predicted weight change after surgery. Conclusion Results suggested that specific problems scales were not more effectively differentiated into more sensitive and specific component scores, but demonstrated supportive evidence that the traditional MMPI-2-RF scales indicating higher degrees of behavioral dysregulation, poor self-efficacy, and lower social support predict reduced postoperative weight loss.