"Clinical Global Impressions" (ECDEU): some critical comments.

Following experience with several clinical trials, the semantic, logical, and statistical properties of the Clinical Global Impressions Scale (CGI-ECDEU, 1976; CIPS, 1986) were investigated. It was concluded that the CGI in its present version (a) may induce inconsistent rating behavior, (b) contains redundant information, (c) consists of items which exhibit extremely abnormal distribution properties. Furthermore (d), some of these items are inappropriately constructed or (e) cast some doubts on their significance as measurements. It is suggested that item #1 (seriousness of disease) be used at the beginning of a study only, and that item #2 (global improvement) be used sparingly and as single measurement to express the doctor's general impression. There would seem to be no basis for the judgment of a pure drug effect (item #3). The instruction to measure improvement by comparing the patient's present condition to that at admission to the study cannot be recommended. Poor distribution properties and a presumably restricted significance of change ratings suggest that parametric statistics should not be referred to.