Clinical Global Impression

The Clinical Global Impression (CGI) is a scale to assess treatment response in patients with mental disorders, such as schizophrenia. The Clinical Global Impression Improvement scale (CGI-I) requires the clinician to rate how much the patient's illness has improved or worsened relative to a baseline state. A patient's illness is compared to change over time and rated as: very much improved, much improved, minimally improved, no change, minimally worse, much worse, or very much worse.

CGI is a three-item scale used to assess treatment response in psychiatric patients. They are: Severity of Illness; Global Improvement; Efficacy Index. Item 1 is rated on a seven-point scale (1=normal to 7=extremely ill); item 2 on a seven-point scale (1=very much improved to 7=very much worse); and item 3 on a four-point scale (from 'none' to 'outweighs therapeutic effect').

The Severity of Illness item 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. Considering total clinical experience, a patient is assessed on severity of mental illness at the time of rating according to: normal (not at all ill); borderline mentally ill; mildly ill; moderately ill; markedly ill; severely ill; or extremely ill.

The Global Improvement item requires the clinician to rate how much the patient's illness has improved or worsened relative to a baseline state. Compared to condition at baseline, a patient's illness is compared to change over time, and rated according to: very much improved; much improved; moderately improved; minimally improved; no change; minimally worse; moderately worse; much worse; or very much worse.