It is useful for clinicians to have at least a basic familiarity with rating scales that are commonly used in clinical trials. Otherwise, it is not really possible to understand the results of the clinical trials that we use to decide whether or not to use an intervention in our clinical practices.
The Clinical Global Impressions scale is very commonly used in clinical trials in mental health. It was introduced in 1976 in a federal publication and is in the public domain. Despite, or perhaps because of, its simplicity, it is one of the most widely used scales in clinical trials in psychopharmacology. Amazingly (to me), there are no standard instructions or standards for using the scale. That it, determination of whether the patient is “minimally improved” or “very much improved,” etc, is at the discretion of the rater.
Subsequent to the development of the original scale, a corresponding Patient Global Impression scale also came into use. Here, the patient is the one who rates the degree of improvement.
Modification of the Clinical Global Impressions scale was developed for use specifically for rating persons with bipolar disorder (Spearing et al., 1997) and for several other conditions.
Clinical Global Impressions-Severity (CGI-S)
Considering your total clinical experience with this patient population, how ill is the patient at this time?
0 = Not assessed
1 = Normal, not ill at all
2 = Borderline ill
3 = Mildly ill
4 = Moderately ill
5 = Markedly ill
6 = Severely ill
7 = Among the most extremely ill patients
Clinical Global Impressions-Improvement (CGI-I)
Rate total improvement whether or not, in your judgment, it is due entirely to drug treatment. Compared to his/her condition at admission to the project (screening) how much has he /she changed?
0 = Not assessed
1 = Very much improved
2 = Much improved
3 = Minimally improved
4 = No change
5 = Minimally worse
6 = Much worse
7 = Very much worse
Guy W. ECDEU Assessment Manual for Psychopharmacology-Revised (DHHS Publ No ADM 91–338). Rockville, MD, U.S. Department of Health and Human Services, 1976, pp 218–222.
Spearing MK, Post RM, Leverich GS, et al: Modification of the Clinical Global Impressions (CGI) scale for use in bipolar illness (BP): the CGI-BP. Psychiatry Res. 1997;73: 159–171.
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