The improved Clinical Global Impression Scale (iCGI): development and validation in depression

BMC Psychiatry

Table 3 Intraclass correlation coefficient of CGI ratings and their 95% confidence intervals.

	CGIs1	95% C.I.	CGIs2	95% C.I.	CGIs1–2	95% C.I.	CGIi	95% C.I.
Group 1	0.64	[0.38, 0.77]	0.70	[0.53, 0.81]	0.64	[0.49, 0.77]	0.65	[0.39, 0.79]
Group 2	0.65	[0.40, 0.79]	0.80	[0.70, 0.87]	0.74	[0.54, 0.82]	0.74	[0.56, 0.84]
Group 3	0.86	[0.72, 0.93]	0.74	[0.57, 0.85]	0.69	[0.41, 0.84]	0.71	[0.53, 0.81]
Group 2'	0.88	[0.73, 0.94]	0.94	[0.90, 0.96]	0.91	[0.79, 0.95]	0.92	[0.83, 0.95]

CGIs measures severity at T1 (CGIs1) at T2 (CGIs2) and CGIi improvement between T2 and T1. CGIs1–2 measures the difference between the CGI severity scores measured at T2 and T1. Group 1 corresponds to 3 raters using the traditional CGI response format. Group 2 corresponds to 4 raters using the improved response format. Group 3 corresponds to a pair of ratings derived from a restricted Delphi procedure (each rating is obtained from 2 clinicians) and using the improved response format. Group 2' is Group 2, but the intraclass correlation coefficient computed here estimates the reliability of the average of 4 ratings derived from independent raters.

ISSN: 1471-244X