Pain-patient Minnesota Multiphasic Personality Inventory (MMPI) subgroups: evaluation of long-term treatment outcome.

Six hundred thirty-five chronic pain patients completed the Minnesota Multiphasic Personality Inventory (MMPI) prior to participation in a multidisciplinary inpatient pain treatment program. Three male and four female MMPI subgroups were identified by means of cluster analyses for each of two samples. Pretreatment and long-term follow-up differences were then examined among the MMPI subgroups. Results indicated that the subgroups identified in the present study closely resembled each other and those previously reported in the literature. However, at long-term follow-up only a few outcome differences were identified among male subgroups, while no differences were found among female subgroups. Possible explanations for no differential treatment outcomes among the MMPI subgroups are discussed.