OBJECTIVE

Despite the frequent use of the Positive and Negative Syndrome Scale (PANSS) for rating the symptoms of schizophrenia, the clinical meaning of its total score and of the cut-offs that are used to define treatment response (e.g. at least 20% or 50% reduction of the baseline score) are as yet unclear. We therefore compared the PANSS with simultaneous ratings of Clinical Global Impressions (CGI).

METHOD

PANSS and CGI ratings at baseline (n = 4091), and after one, two, four and six weeks of treatment taken from a pooled database of seven pivotal, multi-center antipsychotic drug trials on olanzapine or amisulpride in patients with exacerbations of schizophrenia were compared using equipercentile linking.

RESULTS

Being considered "mildly ill" according to the CGI approximately corresponded to a PANSS total score of 58, "moderately ill" to a PANSS of 75, "markedly ill" to a PANSS of 95 and severely ill to a PANSS of 116. To be "minimally improved" according to the CGI score was associated with a mean percentage PANSS reduction of 19%, 23%, 26% and 28% at weeks 1, 2, 4 and 6, respectively. The corresponding figures for a CGI rating "much improved" were 40%, 45%, 51% and 53%.

CONCLUSIONS

The results provide a better framework for understanding the clinical meaning of the PANSS total score in drug trials of schizophrenia patients with acute exacerbations. Such studies may ideally use at least a 50% reduction from baseline cut-off to define response rather than lower thresholds. In treatment resistant populations, however, even a small improvement can be important, so that a 25% cut-off might be appropriate.