Schizophrenia, schizotypal and delusional disorders (section F2): results of the ICD-10 field trial.

To determine whether the use of ICD-10 provides greater diagnostic reliability than ICD-9, a field trial of the ICD-10 draft (WHO, 1987) was carried out. A total of 1,778 diagnoses made on the basis of ICD-10, ICD-9 and, in part, DSM-III were established by 134 clinicians in 10 centres using case reports and interviews. The corrected reliability coefficients of schizophrenic disorders obtained with ICD-10, with kappa-coefficients of reliability of 0.69 for the 2-character category and 0.67 for the 3-character category are higher than those reported for the diagnosis of schizophrenia made without specified criteria, but lower than those reported for DSM-III. Despite the operationally defined diagnostic guidelines, diagnostic discrepancies still persist when organic disturbances, substance abuse or psychogenic features are additionally present. The diagnoses of each rater remain stable on change over from ICD-9 to ICD-10. Our data suggest that ICD-10 is suitable for worldwide use in diagnosing schizophrenia.