Analysis of open answers in the validation of a health-related quality-of-life questionnaire for children

This paper discusses the contribution of lexical analyses of open answers, based on multivariate statistical procedures, to the validation of the EQ-5D(Child), a health-related quality-of-life (HRQL) questionnaire for pediatric age. The basic idea is that children and adolescents’ ideas about health-related concepts may divert from those expected by adults/researchers, thus resulting in misleading interpretations of the intended meaning of the questionnaire’s items. In order to overcome this threat to the content validity of the instrument, 415 participants to the validation study of the Italian version of the EQ-5D(Child) were asked to explain, by means of open answers, the reasons why they reported having difficulties (if they had any) in each of the domains explored by the questionnaire profile (i.e., mobility, self-care, daily activities, pain/discomfort, and worry/sadness/unhappiness). Participants who reported having “no difficulty” were asked to figure out why youths their age might have them. A multiple correspondence analysis was performed on the resulting textual corpus in order to: a) describe the semantic fields associated with each domain; b) pointing out the relationships of proximity/distance between each of the five domains. Perspectives for possible further applications of lexical analyses to the questionnaire validation procedures are also discussed.