Validation of the Headache Impact Test (HIT-6) in patients with chronic migraine

Table 5 Measures of reliability for the HIT-6

Study	N^a	ICC^b	95%confidence interval	Cronbach’s alpha^c		Average inter-item polychoric correlation^c
Study	N^a	ICC^b	95%confidence interval	Baseline	Week 24	Baseline	Week 24
1	362	0.80	[0.75, 0.83]	0.75	0.92	0.45	0.73
2	349	0.76	[0.72, 0.80]	0.79	0.91	0.53	0.72

^aParticipants who, at Week 12, answered “my migraine symptoms are the same” to the question “What effect has your current medication(s) had on your migraine symptoms in the past 4 weeks?”.
^bICC = intra-class correlation coefficient; estimated for measurements made at Weeks 8 and 12.
^cStudy 1: N _baseline = 672; N _{week 24} = 580; study 2: N _baseline = 702; N _{week 24} = 637.
HIT-6 = Headache Impact Test-6.

ISSN: 1477-7525