New scoring methodology improves the sensitivity of the Alzheimer’s Disease Assessment Scale-Cognitive subscale (ADAS-Cog) in clinical trials

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)

ISSN: 1758-9193