Table 2.

Differential item functioning: measurement bias of ADAS-Cog items with respect to gender (men/women) and status of concomitant AChEI symptomatic therapy (yes/no)

DIF factor	ADAS-Cog item	Bias type
Gender	Naming objects & fingers: rattle	d Men < d Women***
Gender	Naming objects & fingers: harmonica	d Men < d Women**
Gender	Constructional Praxis: Cube	d Men < d Women**
Gender	Remembering test instructions	d Men < d Women***
AChEI	Word recall	a Yes < a No***
AChEI	Word recognition	a Yes < a No***
AChEI	Delayed word recall	a Yes < a No***

ADAS-Cog Alzheimer’s disease assessment scale-Cognitive subscale, AChEI acetylcholinesterase inhibitors, DIF differential item functioning, d item intercept/difficulty, a item slope

*indicates the level of significance (**for p-value <10^-4 and ***for p-value <10^-6)