Diagnostic shifts of functional psychoses in the transition from ICD-9 to ICD-10

Abstract

In order to identify diagnostic changes caused by the transition from ICD-9 to ICD-10, in a sample of 218 first hospitalised patients from the years 1980 and 1981, ICD-9 diagnoses were compared with ICD-10 diagnoses. For this comparison, functional psychoses were classified into five main diagnostic groups. Results showed a decreased frequency of the diagnostic groups schizophrenia, schizoaffective psychoses, and paranoid psychoses and an increased frequency of the diagnostic groups acute psychoses and affective psychoses. With the exception of acute psychoses and schizoaffective psychoses, a high agreement between ICD-9 and ICD-10 diagnoses was found, and the Kappa value was 0.70. With regard to the homogeneity of psychopathological symptoms, ICD-10 diagnoses showed no improvement over ICD-9 diagnoses. Nevertheless, ICD-10 diagnoses have gained in predictive validity because schizophrenia was further narrowed to cases with a more unfavourable outcome.