Comparison of the self-administered and interviewer-administered modes of the child-OIDP

BACKGROUND The mode of questionnaire administration may affect the estimates and applicability of oral health-related quality of life indicators. The aim of this study was to compare psychometrically the self-administered Child-OIDP index with the original interviewer-administered instrument. METHODS This was a cross-sectional study of 144 consecutive children aged 9-16 years referred to orthodontic clinics in Bedfordshire. To compare the two administration modes of the Child-OIDP, the sample was randomly split in two groups. The two groups were analysed in terms of baseline characteristics, self-perceived measures (self-rated oral health, self-perceived need for braces, happiness with dental appearance, frequency of thinking about dental appearance), Child-OIDP performance scores and overall score and psychometric properties (criterion validity and internal reliability). RESULTS No significant difference between the two groups was found in relation to their sociodemographic profile and self-perceived measures. The self- and interviewer-administered Child-OIDP had identical mean scores and did not differ in recording any of the eight performances (p > or = 0.206). For criterion validity, the correlation coefficients of the Child-OIDP with self-perceived measures were not different between the two modes of administration (p > or = 0.118). Furthermore, the Cronbach's alpha values of the two groups were similar (p = 0.466). CONCLUSION This study demonstrated that the self-administered Child-OIDP performed the same as the original interviewer-administered mode, while at the same time reducing administration burden. This provides support for the use of the self-administered Child-OIDP. Further studies should focus on a more comprehensive psychometric evaluation.