Validation of the Italian version of the Cystic Fibrosis Quality of Life Questionnaire (CFQoL), a disease specific measure for adults and adolescents with cystic fibrosis.

BACKGROUND: Disease specific, health-related quality of life (HRQoL) measurement is important in cystic fibrosis (CF). This work aimed to translate the original English Cystic Fibrosis Quality of Life Questionnaire (CFQoL) into Italian, evaluate the linguistic translation and to psychometrically evaluate the Italian version of the CFQoL. METHODS: The linguistic translation followed the international guidelines of forward and backward translation. Psychometric evaluation of the Italian CFQoL involved the assessment of construct validity, internal reliability, concurrent validity, known groups validity and test-retest reliability. RESULTS: The instrument was acceptable to adolescents and adults with CF and demonstrated robust psychometric properties. Principle components analysis indicated that the factorial structure was essentially similar to the original, and the internal reliability of each domain was good (Cronbach alpha coefficients 0.73 to 0.91). Appropriate domains of the CFQoL and SF-36 correlated well indicating good concurrent validity (r=0.68-0.80). Consistent with theoretical expectations some domains were able to discriminate between disease severity groups. Test-retest reliability, assessed by intraclass correlation coefficients, was found to be excellent (ICC 0.83 to 0.98). CONCLUSIONS: The Italian CFQoL is a valid and reliable measure. Its use in individual patient monitoring and research should complement traditional clinical outcome measures.