Comparison of the ICD-10-classification with the ICD-9- and the DSM-III-classification of mental disorders.

The diagnostic concepts in ICD-10 show better congruence with those in DSM-III than with those in ICD-9. The diagnostic definitions used by ICD-10 and DSM-III for the majority of diagnoses turn out to be similar; the definitions of anxiety disorders and schizoaffective disorders are, however, still at variance. Consequently, the empirical results from the WHO field trial in German-speaking countries reveal a high degree of overlap between the two systems; the degree of overlap between ICD-9 and ICD-10 was lower, but still surprisingly high overall. These empirical results support the validity of ICD-10.