Cross-cultural French adaptation and validation of the Impact On Family Scale (IOFS)

BACKGROUND: The IOFS (Impact On Family Scale) questionnaire is a useful instrument to assess the impact of chronic childhood conditions on general family quality of life. As this instrument was not validated in French, we proposed to translate, adapt and validate the IOFS questionnaire for clinical and research use in French-speaking populations. FINDINGS: The sample studied comprised French-speaking parents with a child presenting a cleft lip or cleft lip and palate, aged 6 to 12 years and treated in the University Hospital of Strasbourg, France. The 15-item version of the IOFS was translated into French and then sent to the parents by post. The structure of the measure was studied using Exploratory Factor Analysis (EFA), internal consistency was assessed using Cronbach’s alpha coefficient and test-retest reliability was studied by calculating the Intraclass Correlation Coefficient (ICC). A total of 209 parents answered the questionnaire. Its acceptability was good, with 67.9% of mothers and 59.9% of fathers answering the questionnaire. EFA identified one main factor that explained 77% of the variance. Internal consistency was good, with a Cronbach’s alpha of 0.93. Finally, the ICC values were 0.77 (95% confidence interval 0.66–0.85) and 0.87 (95% confidence interval 0.80–0.92) for inter- and intra-observer reliability respectively. CONCLUSIONS: The French version of the IOFS questionnaire exhibited very good psychometric properties. For practitioners, this instrument will facilitate the assessment of the impact of chronic childhood conditions on quality of life among French-speaking families.