An empirical study of five sets of diagnostic criteria for delusional disorder

The diagnosis of paranoia/delusional disorder has been significantly modified and redefined from DSM-III to DSM-5, which in turn also meaningfully differ from the ICD-10 criteria. In this study we examined the degree to which these diagnostic systems differ on external variables.

Two-hundred and eighty-six subjects diagnosed of paranoia/delusional disorder according to DSM-III, DSM-III-R, DSM-IV, DSM-5 or ICD-10 criteria were examined for a number of validators including risk factors, premorbid features, illness-related variables and psychosocial functioning. The prevalence rates of the diagnostic criteria and their concordance level were examined, such as the degree to which the criteria sets and their main diagnostic features were differentially related to the validators.

Diagnostic criteria showed poor to fair concordance. The most inclusive system was the DSM-5 (n = 274) and the most restrictive the DSM-III (n = 187). Compared with subjects fulfilling other diagnostic criteria, those with a DSM-III diagnosis showed more and stronger associations with the validators: presence of cluster A personality disorders, insidious illness onset, poor response to treatment, chronic illness course and poor psychosocial functioning. This association pattern was mainly due to the 6-month duration criterion. Stability of delusions, type of delusions and the ICD-10 3-month duration criterion were poorly related to the validators.

Diagnostic criteria for delusional disorder are not interchangeable. DSM-III criteria for paranoia may identify a more severe disorder mainly because the 6-month duration criterion. Type of delusions had a small impact on the validators across diagnostic systems. These findings have implications for future classifications of delusional disorder.