Symptom correlates of global measures of severity in schizophrenia

There is an increasing need for practical instruments that can rapidly and accurately assess the effectiveness of treatments for mental illness in cli nical settings. Symptom rating scales used in clinical research are too com plex and time-consuming to be useful in these settings. In contrast, single -item global measures of severity such as the Clinical Global Impression-se verity scale (CGI) and the Global Assessment of Function scale (GAF) are br ief and easy to complete, but little is known about their relationship with the specific symptoms of severe mental illnesses. In this study, we examin e the extent to which CGI and GAF scores reflect the severity and the chang e in severity of positive, negative, depressive, and agitation symptoms in a sample of 102 schizophrenia inpatients at the University of Michigan Medi cal Center. At admission, positive symptoms were the strongest correlates o f both CGI and GAF scores, followed by negative symptoms, and agitation. De pressive symptoms did not correlate significantly with either global measur e. The three symptom scores together explained 58% of the variation in CGI and 39% of the variation in GAF. A similar pattern of association was found for the scores measured at discharge and for the relationships between the change in global measures and change in specific symptom clusters. Thus, b y demonstrating that single-item global measures, particularly the CGI, can be reasonably good indicators of psychopathology, this study suggests that these measures may be practical tools for routine monitoring of the effect iveness of treatments for severe mental illness in community settings. Copy right (C) 1999 by W.B. Saunders Company.