title: The Short-Form Headache Impact Test (HIT-6) was psychometrically equivalent in nine languages.
abstract: OBJECTIVE
  This study examined the psychometric properties and equivalence of the six-item Headache Impact Test (HIT-6) across 11 languages in 14 countries.
  
  
  METHODS
  A multicenter, international cross-sectional study conducted in a primary care setting. Data obtained from 1,171 adults from 14 countries who consulted their primary care physician for headache completed the HIT-6 questionnaire and a headache survey were included in this analysis. Item-level statistics (e.g., range of response choices used by participants), item-scale statistics (e.g., item-total correlations), scale level statistics (e.g., internal consistency reliability), and tests of differential item functioning were conducted to examine the psychometric properties of all HIT-6 translations and their comparability across translations.
  
  
  RESULTS
  Across languages, missing data were low, item-scale correlations were high, reliability was adequate, and item-level statistics were generally comparable. We found only minor differential item functioning, suggesting that the HIT-6 translations are equivalent to the U.S. English form.
  
  
  CONCLUSIONS
  Psychometric analyses indicate that most HIT-6 translations (Canadian English, French, Greek, Hungarian, UK English, Hebrew, Portuguese, German, Spanish, and Dutch) are comparable to U.S. English. Improvements may be needed in the Finnish and Slovakian translations and the appropriateness of using the HIT-6 in South Africa should be explored further.
authors.affiliation: QualityMetric Incorporated, 640 George Washington Highway, Lincoln, RI 02865, USA. mmartin@qualitymetric.com
authors.forename: Marie
authors.initials: M
authors.lastname: Martin
authors.forename: Bonnie
authors.initials: B
authors.lastname: Blaisdell
authors.forename: Jackie W
authors.initials: JW
authors.lastname: Kwong
authors.forename: Jakob B
authors.initials: JB
authors.lastname: Bjorner
mesh_terms: D003430:Cross-Sectional Studies; D006261:Headache / Q000523:psychology*; D006305:Health Status Indicators; D006801:Humans; D007802:Language; D011594:Psychometrics; D011788:Quality of Life