Validation of the CPAP Habit Index-5: A Tool to Understand Adherence to CPAP Treatment in Patients with Obstructive Sleep Apnea

Table 4

Homogeneity and factor structure among items of the CPAP Habit Index-5 after 6 months of CPAP use (𝑛=116)¹.

Items	Interitem correlations					Factor analysis
	1	2	3	4	5	Factor	Uniqueness
(1) Using the CPAP nightly is part of my routines a normal week	0.818^b					0.936	0.124
(2) A special reason is needed if I'm not going to use the CPAP during a normal night	0.585***	0.955^b				0.700	0.511
(3) I have used the CPAP nightly for a long time	0.887***	0.591***	0.918^b			0.918	0.157
(4) It feels weird not to use the CPAP during a normal night	0.696***	0.421***	0.710***	0.896^b		0.822	0.324
(5) I use the CPAP more or less automatically during a normal night	0.929***	0.593***	0.846***	0.753***	0.792^b	0.955	0.088
Explained variance						0.759
Kaiser-Meyer-Olkin						0.859
Bartlett test of sphericity						𝜒^2 (10) = 510.1, <0.001
Cronbach’s 𝛼						0.915
Cronbach’s 𝛼 95% CI^a						0.878/0.941

aBias-corrected (based on bootstrapping with 1000 replications)
^bMeasure of sampling adequacy.
1One participant excluded according to missing data in item no 3.
^∗∗∗𝑃<0.001.