A major goal for the revision of the International Classification of Diseases and Related Health Problems, Tenth Edition (ICD-10) is to increase the clinical utility of the diagnostic system. Schizoaffective disorder has a history of poor diagnostic reliability due to the similarities and overlap in symptoms that it shares with other disorders, especially primary psychotic and mood disorders. The present study was part of the case-controlled field trials for ICD-11 and examines how the proposed changes for schizoaffective disorder may improve differential diagnosis and diagnostic accuracy. Clinicians from around the globe (n = 873) were provided with either ICD-10 or ICD-11 diagnostic guidelines and asked to apply them to case vignettes comparing schizoaffective disorder to schizophrenia and mood disorders with psychotic symptoms. Participants were asked to respond to follow-up diagnostic questions to determine which components of the diagnostic guidelines affected diagnostic accuracy. Overall, clinicians showed small improvements in accurately diagnosing vignettes using ICD-11 over ICD-10. Results suggest the discrepancy in diagnosing schizoaffective disorder is related primarily to the presence of mood symptoms and discrepancies about whether those symptoms are more consistent with schizoaffective disorder or a mood disorder diagnosis. Continuing to identify ways to more accurately capture this symptom picture will be important in the future as well as systematic efforts to educate clinicians about differential diagnosis.
Keywords: Diagnosis; ICD-11; Mood disorders; Reliability; Schizoaffective disorder; Schizophrenia.
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