Specificity of Incident Diagnostic Outcomes in Patients at Clinical High Risk for Psychosis

It is not well established whether the incident outcomes of the clinical high-risk (CHR) syndrome for psychosis are diagnostically specific for psychosis or whether CHR patients also are at elevated risk for a variety of nonpsychotic disorders. We collected 2 samples (NAPLS-1, PREDICT) that contained CHR patients and a control group who responded to CHR recruitment efforts but did not meet CHR criteria on interview (help-seeking comparison patients [HSC]). Incident diagnostic outcomes were defined as the occurrence of a SIPS-defined psychosis or a structured interview diagnosis from 1 of 3 nonpsychotic Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) groups (anxiety, bipolar, or nonbipolar mood disorder), when no diagnosis in that group was present at baseline. Logistic regression revealed that the CHR vs HSC effect did not vary significantly across study for any emergent diagnostic outcome; data from the 2 studies were therefore combined. CHR (n = 271) vs HSC (n = 171) emergent outcomes were: psychosis 19.6% vs 1.8%, bipolar disorders 1.1% vs 1.2%, nonbipolar mood disorders 4.4% vs 5.3%, and anxiety disorders 5.2% vs 5.3%. The main effect of CHR vs HSC was statistically significant (OR = 13.8, 95% CI 4.2-45.0, df = 1, P < .001) for emergent psychosis but not for any emergent nonpsychotic disorder. Sensitivity analyses confirmed these findings. Within the CHR group emergent psychosis was significantly more likely than each nonpsychotic DSM-IV emergent disorder, and within the HSC group emergent psychosis was significantly less likely than most emergent nonpsychotic disorders. The CHR syndrome is specific as a marker for research on predictors and mechanisms of developing psychosis.