Failure of the Hs-PT index to distinguish organic from functional patients

Investigated the effectiveness of the MMPI Hs-PT index to separate patients with a brain disorder from those with functional disturbance. A sample of 303 male patients who were referred for neuropsychological evaluation because of known or suspected brain damage was used in the study. Of these, 187 were diagnosed as organic and 116 as functional. The Hs-PT index failed to separate these groups beyond a chance level. Hit rates were 52.4% for the organic patients and 36.2% for the functional patients using the cut-off established in previous research. No discriminations were possible at any of the Hs-PT ranges. Failure of the Hs-PT index to hold up in this sample of patients is probably due to some very different patient characteristics from those prevalent in earlier research.