Abstract
OBJECTIVE: Impact of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) changes on the criteria for schizophrenia (SZ) has been reported to be minimal in previous studies. However, this could be different in first-episode schizophrenia spectrum disorders (FE-SSDs). We investigated what proportion of patients with FE-SSDs was diagnosed based on the sole presence of bizarre delusions (BDs) or first rank auditory hallucinations (FRAHs). Their alternative diagnosis by the DSM-5 was established and diagnostic stability over 1-year was identified. METHODS: This was a retrospective review study on the medical records, case report forms for the subjects with FE-SSDs (n=404) participated in the Korea Early Psychosis Study. The two Japanese sites reviewed retrospectively only medical records of the subjects with FE-SSDs (n=103). We used three different definitions of BDs (strict, narrow, and broad) and specified subtypes of Other Specified Schizophrenia spectrum and Other psychotic disorders (OSSOs). To ensure inter-rater reliability between the hospitals, regular zoom meetings were held. RESULTS: Forty (7.89%) subjects out of 507 were found to be diagnosed as SSDs based on the sole presence of BDs or FRAHs. All these patients met the criteria of OSSOs and were classified as having pure delusion (n=22), delusion with attenuated auditory hallucinations (AHs) (n=5), pure AHs (n=3) and AHs with attenuated delusion (n=10). The patients with first and second subtypes (n=27) were found to have BDs. The BDs fulfilled mostly strict definitions or satisfied the next broadest definition. The diagnostic stability of FE-OSSOs and its subgroups (first and second subtypes) over 1-year was substantially high (70.27% and 84% respectively). CONCLUSION: These findings suggest that more rigorous diagnostic assessment should be performed especially to differentiate OSSOs from SZ in patients with FE-SSDs and more refined classification of the subtypes for OSSOs considered in the next DSM revision.