A dimensional approach to severe delusional psychoses.

By use of latent trait models a 7-item rating scale of severe delusional psychoses was established based on the PSE interview. Data from 88 first-admitted patients with delusional psychoses were analysed. These data assigned good internal validity of the scale and revealed a dimensional rather than a categorical distribution of severe delusional psychoses. Using schizophrenia as a reference, the scale with a cut-off point greater than or equal to 1 established the diagnosis with a sensitivity of 0.84 and a specificity of 0.95. In a study to come a latent class analysis among deluded patients will be performed.