The MMPI and clinical diagnosis: a comparison of classification system outcomes with discharge diagnoses

This study examined the agreement or congruence rate between clinical-discharge diagnoses rendered by a psychiatrist, and admission and discharge MMPI-derived diagnoses from four diagnostic classification systems that have been developed for the MMPI. The four classification systems included a simple high-point code based on the most elevated clinical scale in the profile, the Henrichs revision of the Meehl-Dahlstrom rules, the Goldberg equations, and a system developed by Lachar. Subjects consisted of 150 patients selected from a larger pool of patients who had completed a 9-week adult residential treatment program. Overall, this study yielded modest hit rates between 26% and 34% for MMPI-derived diagnoses and psychiatric diagnoses across the various classification systems. In addition, stability of MMPI-based diagnoses from admission to discharge assessments ranged from 48% to 51% depending on the classification system employed. Findings are discussed in terms of their implications for the use of the MMPI in patient diagnosis. It is recommended that the MMPI be used in conjunction with other sources of clinical and test information in deriving clinical diagnoses.