title: Validation of the Headache Impact Test (HIT-6) in patients with chronic migraine.
abstract: BACKGROUND
  The Headache Impact Test (HIT)-6 was developed and has been validated in patients with various types of headache. The objective of this study was to report the psychometric properties of the HIT-6 among patients with chronic migraine.
  
  
  METHODS
  Data came from two international, multicenter, randomized, double-blind, placebo-controlled clinical trials of chronic migraine patients (N = 1,384) undergoing prophylaxis therapy. Confirmatory factor analysis and differential item functioning (DIF) analysis were used to test the latent structure and cross-cultural comparability of the HIT-6. Reliability, construct validity, and responsiveness were assessed. Two sets of criterion groups were used: (1) 28-day headache frequency: <10, 10-14, and ≥15 days; (2) sample quartiles of the total cumulative hours of headache: <140, 140 to <280, 280 to <420, and ≥420 hours. Two sets of responsiveness categories were defined as reduction of <30%, 30% to <50%, or ≥50% in (1) number of headache days and (2) cumulative hours of headache.
  
  
  RESULTS
  Measurement invariance tests supported the stability of the HIT-6 latent structure across studies. DIF analysis supported cross-cultural comparability. Good reliability was observed across studies (Cronbach's α: 0.75-0.92; intraclass correlation coefficient: 0.76-0.80). HIT-6 scores correlated strongly (-0.86 to -0.59) with scores of the Migraine-Specific Quality-of-Life Questionnaire. Analysis of variance indicated that HIT-6 scores discriminated across both types of criterion groups (P<0.001), across studies and time points. HIT-6 change scores were significantly higher in magnitude in groups experiencing greater improvement (P<0.001).
  
  
  CONCLUSIONS
  All measurement properties were consistently verified across the two studies, supporting the validity of the HIT-6 among chronic migraine patients.
  
  
  BACKGROUND
  NCT00156910 and NCT00168428 on www.ClinicalTrials.gov.
authors: Regina
authors: R
authors: Rendas-Baum
authors: Min
authors: M
authors: Yang
authors: Sepideh F
authors: SF
authors: Varon
authors: Lisa M
authors: LM
authors: Bloudek
authors: Ronald E
authors: RE
authors: DeGryse
authors: Mark
authors: M
authors: Kosinski
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002908:Chronic Disease; D003431:Cross-Cultural Comparison; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000175:diagnosis*; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D055815:Young Adult