Determinants of patient-rated and clinician-rated illness severity in schizophrenia

Objective: The contribution of specific symptoms on ratings of global illness severity in patients with schizophrenia is not well understood. The present study examined the clinical determinants of clinician and patient ratings of overall illness severity. Method: This study included 1,010 patients with a DSM-IV diagnosis of schizophrenia who participated in the baseline visit of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study conducted between January 2001 and December 2004 and who had available symptom severity, side effect burden, cognition, and community functioning data. Both clinicians and patients completed the 7-point Clinical Global Impressions-Severity of Illness scale (CGI-S), the primary measure of interest in the present study. Symptoms were rated using the Positive and Negative Syndrome Scale and the Calgary Depression Scale for Schizophrenia, and functional status with the Quality of Life Scale. Neurocognition, insight, and medication-related side effects were also evaluated. Results: Clinicians rated illness severity significantly higher than patients (P <.001). There was moderate overlap between CGI-S ratings made by clinicians and patients, with almost one third of patients showing substantial (ie, greater than 1 point) discrepancies with clinician ratings. Clinician-rated CGI-S scores were most strongly associated with positive symptoms, with additional independent contributions made by negative, disorganized, and depressive symptoms, as well as functional outcome (all P values <.01). Patient-rated CGI-S scores, on the other hand, were most closely related to depressive symptoms, with additional independent contributions made by positive and anxiety symptoms, clinical insight, and neurocognition (all P values <.01). Depressive symptoms were the strongest predictor of patient-rated CGI-S scores even in patients with good clinical insight (P <.001). Conclusions: Patient and clinician views of overall illness severity are not necessarily interchangeable and differ in their clinical correlates. Taking these differences into account may enhance patient engagement in care and improve outcomes.