title: Translation, validation, and construct reliability of a Portuguese version of the Xerostomia Inventory.
abstract: OBJECTIVE
  To generate and validate at pretest level a cross-culturally adapted Portuguese version of Xerostomia Inventory (XI), a 11-item questionnaire designed to measure specific xerostomia rating of patients complaints.
  
  
  METHODS
  The original English version of the XI was translated into Portuguese following the guidelines for cross-cultural adaptation of health-related quality of life measures. Thirty patients with primary Sjögren syndrome were recruited for this study. The questionnaires were administered by trained and calibrated dental doctors to each patient. XI properties were examined including reliability, internal consistency, and test-retest reliability, using Cronbach's alpha, total and inter-item correlation, and intra-class correlation coefficients (ICC), respectively. Construct validity supported by objective measurements of xerostomia intra-oral signs and salivary secretion was investigated. Alpha was set at 0.05. Informed consents and local ethical committee clearance were obtained.
  
  
  RESULTS
  Internal consistency and test-retest reliability were excellent (Cronbach's α=0.9; ICC range=0.79-0.94). Scatterplot interpolation and Pearson correlation coefficient suggested the presence of a strong, negative, and significant correlation between salivation and the XI scores indicating construct validity.
  
  
  CONCLUSIONS
  The Portuguese version of the XI can be considered a reliable and valid instrument to measure patients' xerostomia symptoms.
authors.affiliation: Oral Biology and Biochemistry Group, Biomedical and Oral Sciences Research Unit (FCT Unit 4062), Faculty of Dentistry, University of Lisbon, Portugal. admata2@yahoo.com
authors.forename: A D S P
authors.initials: AD
authors.lastname: da Mata
authors.forename: D N
authors.initials: DN
authors.lastname: da Silva Marques
authors.forename: F M F
authors.initials: FM
authors.lastname: Freitas
authors.forename: J P
authors.initials: JP
authors.lastname: de Almeida Rato Amaral
authors.forename: R T V M R
authors.initials: RT
authors.lastname: Trindade
authors.forename: F A D
authors.initials: FA
authors.lastname: Barcelos
authors.forename: J M
authors.initials: JM
authors.lastname: Vaz Patto
mesh_terms: D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007802:Language; D008875:Middle Aged; D011174:Portugal; D012463:Saliva / Q000378:metabolism; D012636:Secretory Rate; D057566:Self Report; D012859:Sjogren's Syndrome / Q000175:diagnosis; D011795:Surveys and Questionnaires / Q000592:standards; D014175:Translating; D014987:Xerostomia / Q000175:diagnosis* / Q000503:physiopathology