Clinical global impression

Despite its wider acceptance and consistent use in clinical trials, psychometric properties of CGI have not been established. However, the scale is found to be valid as an external criterion during the development of scales of depression and anxiety. In many studies, the clinicians' ratings of psychiatric symptoms were found to correlate significantly with self-rated and other valid scales of symptom severity. For example, Leon et al. (1993){{Cite journal|url=https://pubmed.ncbi.nlm.nih.gov/8227491/|pmid = 8227491|year = 1993|last1 = Leon|first1 = A. C.|last2 = Shear|first2 = M. K.|last3 = Klerman|first3 = G. L.|last4 = Portera|first4 = L.|last5 = Rosenbaum|first5 = J. F.|last6 = Goldenberg|first6 = I.|title = A comparison of symptom determinants of patient and clinician global ratings in patients with panic disorder and depression|journal = Journal of Clinical Psychopharmacology|volume = 13|issue = 5|pages = 327–31|doi = 10.1097/00004714-199310000-00005}} showed that severity ratings but not improvement ratings were predicted highly and significantly by frequency of panic attacks, depression and anxiety ratings made on already valid rating scales. Similarly, another study{{Cite journal|url=https://pubmed.ncbi.nlm.nih.gov/12409681/|pmid = 12409681|year = 2002|last1 = Khan|first1 = A.|last2 = Khan|first2 = S. R.|last3 = Shankles|first3 = E. B.|last4 = Polissar|first4 = N. L.|title = Relative sensitivity of the Montgomery-Asberg Depression Rating Scale, the Hamilton Depression rating scale and the Clinical Global Impressions rating scale in antidepressant clinical trials|journal = International Clinical Psychopharmacology|volume = 17|issue = 6|pages = 281–5|doi = 10.1097/00004850-200211000-00003|s2cid = 871694}} showed that MADRS, HAM-D and CGI scales had comparable effect sizes and could be equally used in studies to assess severity and improvement of symptoms.

Even though many studies have established the validity of CGI scales in relation to other commonly used robust rating scales, its efficacy in predicting treatment outcomes is highly debated. Its sensitivity is good enough to differentiate between responders and non-responders in clinical trials of depression,Guelfi JD: Clinical research in psychopharmacology: new standards for drug development. An application to antidepressants. Psychiatrie et Psychobiologie. 1990, 5: 289-294 but its specificity is not satisfactory. It has poorer interrater reliability than HAM-D.Cicchetti DV, Prusoff BA: Reliability of depression and associated clinical symptoms. Arch Gen Psychiatry. 1983, 40: 987-990

Many weaknesses could explain this possible lack of validity of the CGI: there is no specific interviewer guide available, and while most other symptoms scales have fairly clear and specific response options, the response format used in the CGI to assess change or severity of illness is more likely to be ambiguous (what is the definition of a patient who is "Severely ill"?).{{Cite journal|url= |doi = 10.1186/1471-244X-7-7|title = The improved Clinical Global Impression Scale (ICGI): Development and validation in depression|year = 2007|last1 = Kadouri|first1 = Alane|last2 = Corruble|first2 = Emmanuelle|last3 = Falissard|first3 = Bruno|author3-link= Bruno Falissard |journal = BMC Psychiatry|volume = 7|page = 7|pmid = 17284321|pmc = 1802073 | doi-access=free }}

The clinical global impression – severity scale (CGI-S) is a 7-point scale that requires the clinician to rate the severity of the patient's illness at the time of assessment, relative to the clinician's past experience with patients who have the same diagnosis. Clinicians ask: "Considering your total clinical experience with this particular population, how ill is the patient at this time?" Possible ratings are:

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1. Normal, not at all ill
2. Borderline mentally ill
3. Mildly ill
4. Moderately ill
5. Markedly ill
6. Severely ill
7. Among the most extremely ill patients

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The clinical global impression – improvement scale (CGI-I) is a 7-point scale that requires the clinician to assess how much the patient's illness has improved or worsened relative to a baseline state at the beginning of the intervention. Clinicians ask: "Compared to the patient's condition at baseline, this patient's [average] condition has...?" and rated as:

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1. Very much improved
2. Much improved
3. Minimally improved
4. No change
5. Minimally worse
6. Much worse
7. Very much worse

}}

The clinical global impression – efficacy Index is a 4×4 rating scale that assesses the therapeutic effect of treatment with psychiatric medication and associated side effects.

• Diagnostic classification and rating scales used in psychiatry
• Outcomes research

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• {{cite book |last=Guy |first=W. |chapter=Clinical Global Impressions (CGI) Scale, Modified |editor1-last=Rush |editor1-first=John A. |editor2=Task Force for the Handbook of Psychiatric Measures |title=Handbook of Psychiatric Measures |publisher=American Psychiatric Association |edition=1st |location=Washington, DC |date=2000 |oclc=43483679 |isbn=978-0-89042-415-5 |url-access=registration |url=https://archive.org/details/handbookofpsychi0000amer }}

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{{NIMH|author=William Guy|article=ECDEU Assessment Manual for Psychopharmacology—Revised, 1976|url=https://archive.org/details/ecdeuassessmentm1933guyw}}

Category:Global screening and assessment tools in psychiatry