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Table 5 Measures of reliability for the HIT-6

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

Study Na ICCb 95%confidence interval Cronbach’s alphac Average inter-item polychoric correlationc
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
  1. 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?”.
  2. bICC = intra-class correlation coefficient; estimated for measurements made at Weeks 8 and 12.
  3. cStudy 1: N baseline = 672; N week 24 = 580; study 2: N baseline = 702; N week 24 = 637.
  4. HIT-6 = Headache Impact Test-6.