Chronic Airways Assessment Test: psychometric properties in patients with asthma and/or COPD

Respiratory Research

Table 2 Mean boundary difference and p values for uniform DIF between patients with asthma and COPD^a

Item	Description	Mean boundary difference (Asthma–COPD)	p value for uniform DIF
1	Cough	0.559	0.003579
2	Phlegm	–0.012	0.282105
3	Chest tightness	0.072	0.126434
4	Breathlessness	–0.824	0.000009
5	Home activity	–0.724	0.000002
6	Confidence	–0.448	0.12692
7	Sleep	0.162	0.000737
8	Energy	–0.324	0.516946

Mean boundary difference for each CAAT item was calculated as the mean CAAT item score for patients with asthma subtracted by the mean CAAT item score for patients with COPD. A negative value indicates a lower response in patients with asthma. Responses to individual CAAT items ranged from 0 to 5
CAAT Chronic Airways Assessment Test, COPD chronic obstructive pulmonary disease, DIF differential item functioning
^aNone of the CAAT items showed significant non-uniform DIF

ISSN: 1465-993X