Relationship between symptomatic improvement and overall illness severity in patients with schizophrenia

Background Whether improvement on ratings of global illness severity is differentially associated with improvement in specific symptom domains in patients with schizophrenia is not well understood. The present study examined the independent relationships between improvement in specific symptom clusters and change in global impressions of illness severity. Methods This study included 589 patients with chronic schizophrenia who were assessed at baseline and after 6 months of antipsychotic treatment. Both clinicians and patients completed the Clinical Global Impressions-Severity of Illness Scale (CGI-S). Symptom severity was assessed using factor scores derived from the Positive and Negative Syndrome Scale. Results Change in illness severity ratings made by the clinician and those made by the patient demonstrated moderate overlap. Nearly half of the patients were evaluated as clinically improved during the 6-month period, as rated by the clinician, with less than a third of patients experiencing a reduction in illness severity as determined by both the clinician and themselves. Improvements in clinician-rated CGI-S scores were most strongly associated with reduction in positive symptom severity. In contrast, change in patient-rated CGI-S scores was not linked to reduction in positive symptoms but rather to improvement in depressive and anxiety symptoms. This latter finding remained in a subsample of patients with relatively preserved insight into illness, suggesting that lack of insight cannot account for these findings. Finally, reduction in positive symptoms beyond 2 to 3 points was found to be clinically meaningful. Conclusions In conclusion, change in overall illness severity, as determined by clinicians, is not necessarily interchangeable with patients' view of improvement of their own clinical status. Moreover, changes in the 2 evaluations of illness severity are associated with changes in different symptom domains.