MMPI profiles of opiate addicts: predicting response to treatment.

Although many studies document the use of the MMPI to classify opiate users, the predictive validity of the resulting subgroups is rarely reported. In this study, we used cluster analysis to identify MMPI profile types that predicted differential response to methadone maintenance treatment. Participants (N = 151) completed MMPIs shortly after entry into treatment. Cluster analysis of MMPI scores produced four distinct subgroups that differed significantly in severity of psychosocial problems measured at admission and on the mean number of drug-free urine specimens submitted during the 24-week study period. Cluster 1 participants evidenced low levels of psychological disturbance, improved their urinalysis results over time, and submitted the most posttest drug-free urine specimens. Cluster 2 was the only other group that improved significantly over time, even though these patients were the most psychologically disturbed. The results suggest the relation between psychological problems and outcome may be more complex than is commonly assumed.