DSM-III diagnoses compared with factor structure of the psychopathology instrument for mentally retarded adults (PIMRA), in an institutionalized, mostly severely retarded population.

The Psychopathology Instrument for Mentally Retarded Adults (PIMRA) was used to diagnose 163 mentally retarded adults in an institution according to DSM-III axis 1 categories. The relevant 49 items of the PIMRA were subsequently factor analysed. The factors were compared with the diagnoses to examine similarities or differences. The nine factors extracted contained 49.3% of the variance in the data, and were able to categorize correctly 69.3% of the cases with regards to diagnosis through a discriminant analysis. This is statistically different from chance expectations (p less than 0.001) and gives an inter-method agreement of 87.86% and a kappa of 0.62. Some of the factors were recognized as important aspects of traditional psychiatric categories. This makes these diagnostic categories more credible as valid diagnoses for persons from a population like the one studied.