Psychometric properties of an instrument for assessing the experience of patients treated with inhaled insulin: the Inhaled Insulin Treatment Questionnaire (IITQ)

Table 2 Scale Statistics

	T1	T1	T1	T2	T2	T2
Measure (# of items)	Test	Retest	Test-Retest	Test	Retest	Test-Retest
Diabetes Worries (5)
Mean^a	74.0	74.5	p = .348	75.2	76.8	p = .009
SD	16.7	16.9		17.4	16.2
% max, % min	0.2,7.7	0.6,8.1		0.4,9.0	0.4,9.3
Reliability^b	.71	.75	.81	.68	.70	.77
Perceptions of Insulin Therapy (16)
Mean^a	58.2	56.9	p = .001	57.0	56.4	p = .191
SD	14.9	15.0		15.9	15.9
% max, % min	0.2,0.0	0.2,0.0		0.2,0.0	0.2,0.7
Reliability^b	.85	.87	.90	.84	.86	.85
Treatment Satisfaction (3)
Mean^a	53.3	54.1	p = .285	52.5	53.6	p = .248
SD	21.4	21.2		23.9	24.6
% max, % min	2.2,1.6	1.8,1.8		2.8,2.8	2.3,4.6
Reliability^b	.83	.85	.83	.81	.85	.74
Treatment Preference (1)
Mean^a	69.2	66.8	p = .020	58.1	58.3	p = .887
SD	26.0	25.3		30.3	29.0
% max, % min	3.7,21.0	3.5,16.9		7.4,13.8	6.9,11.6
Reliability^b	na	na	.73	na	na	.67

^a Test-Retest is the p-value for paired t-test of difference in means across administrations.
^b Reliability for each administration is Cronbach's alpha (na = not applicable); Test-Retest reliability is the intraclass correlation coefficient.

ISSN: 1477-7525