Medical Terminology

Clinical Global Impression scales (CGI)

« Back to Glossary Index

There are two types of CGI (Clinical Global Impression) scales, which vary depending on the precise issue the professional or researcher is assessing. The first is the Clinical Global Impression-Severity (CGI-S) scale, which is a 7-point scale that healthcare professionals or researchers (clinicians) use to rate the patient’s severity of illness at the time of assessment, relative to the clinician’s past experience with patients who have the same diagnosis. Responses include: 1) normal or not at all ill; 2) borderline mentally ill; 3) mildly ill; 4) moderately ill; 5) markedly ill; 6) severely ill; or 7) among the most extremely ill patients. The second scale is the Clinical Global Impression-Improvement scale (CGI-I), which 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 an intervention. Responses include: 1) very much improved; 2) much improved; 3) minimally improved; 4) no change; 5) minimally worse; 6) much worse; or 7) very much worse.