Developing a short-form version of the HIV Disability Questionnaire (SF-HDQ) for use in clinical practice: a Rasch analysis

Table 3 Cognitive Domain (3 items) - Overview of final SF-HDQ item level and domain model fit statistics

Item #	Final SF-HDQ items	Item level statistics
Cognitive domain		Location	SE	Residual	ChiSq χ ²	p value
21	Trouble remembering like appointments and when to take medication	− 0.072	0.058	2.764*	20.271	0.005*
22	Trouble thinking clearly	0.498	0.061	− 1.078	34.33	< 0.001^a
23	Trouble concentrating	− 0.427	0.060	− 0.918	21.292	0.003^a
Final model: cognitive domain—3 items (raw score range: 0–12)
Mean		− 1.813
Standard deviation		1.764
Sample size		730
Chi-square statistic (df) p value		75.8970 (df: 21); p < 0.001
Cronbach’s alpha		0.77602
Person Separation Index		0.70994
Unidimensionality t-test (% significant)		1.23%
Differential Item Functioning (DIF)		None

^*Item fit residual for HDQ21 (2.764) significant (p < 0.017; Bonferroni: 0.05/3) but retained due to clinical importance and need for minimum of 3 items in domain
^aSignificant residual (p < 0.017; Bonferroni: 0.05/3) but fit residual F value < ± 2.5

ISSN: 1477-7525