. Author manuscript; available in PMC: 2012 Nov 1.

Published in final edited form as: Alzheimers Dement. 2011 Nov;7(6):593–601. doi: 10.1016/j.jalz.2011.02.007

Table 2.

Discrimination between diagnostic groups for each version of the ECog.

	Test	AUC	Specificity (with 80% sensitivity)	Optimal cut-off score^*
Impaired^* vs. Normal	ECog-39	.91 (CI = .88-.93)	84%	1.81
Impaired^* vs. Normal	ECog-12	.91 (CI = .88-.93)	81%	2.30
Dementia vs. Normal	ECog-39	.96 (CI = .94-.97)	95%	2.34
Dementia vs. Normal	ECog-12	.95 (CI = .94-.97)	95%	2.83
Dementia vs. MCI	ECog-39	.85 (CI = .82-.89)	74%	2.35
Dementia vs. MCI	ECog-12	.80 (CI = .76-.84)	64%	2.83
MCI vs. Normal	ECog-39	.79 (CI = .74-.83)	61%	1.32
MCI vs. Normal	ECog-12	.79 (CI = .74 - .84)	62%	1.54
Impaired2^** vs. Normal	ECog-39	.87 (CI = .84-.90)	77%	1.58
Impaired2^** vs. Normal	ECog-12	.88 (CI = .85 - .91)	78%	2.0
Mild Dementia vs. MCI	ECog-39	.80 (CI = .76-.85)	74%	2.12
Mild Dementia vs. MCI	ECog-12	.74 (CI = .69-.79)	58%	2.70
Mild Dementia vs. Normal	ECog-39	.94 (CI = .92-.97)	91%	2.12
Mild Dementia vs. Normal	ECog-12	.94 (CI = .92-.97)	92%	2.70

This is based on a sum of the item scores divided by the total number of items completed by the informant (range:1 = no change/better performance than in the past to 4 = consistently much worse than in the past).

^**

Impaired = persons who had a clinical diagnosis of dementia or MCI