Reducing Minnesota Multiphasic Personality Inventory defensiveness: effect of specialized instructions on retest validity in a sample of preoperative bariatric patients.

Background: Because of the possibility of being denied or delayed surgery, bariatric patients might have a motivation to minimize any emotional difficulties in the preoperative psychological evaluation. This study examined changes in the psychometric test scores when extremely defensive patients were asked to repeat the testing.

Methods: Changes in the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) scale scores were studied in a subsample of patients referred to the author for a preoperative psychological evaluation. After producing defensive MMPI-2 test profiles, these bariatric patients (n = 31) were provided feedback on their defensiveness and asked to be more open and honest on the repeat testing.

Results: The vast majority (94%) of the patients produced valid profiles on the second test. On the second test, significant differences were found on 6 of the 13 MMPI-2 scales, as well as on separate measures of depression, anxiety, and anger.

Conclusion: It appears to be important to include a psychometric measure that includes a validity scale in the evaluation process, because patients might be motivated to present in a defensive or overly virtuous light in fear that a negative evaluation from the psychologist would adversely affect a decision regarding their candidacy for surgery. It is recommended that patients who are defensive in their testing be asked to repeat the test battery.