Aim: The aim of this study was to validate a proxy measure of oral health designed to be completed by the English-speaking parents of people with Down syndrome (DS) aged four years or more.
Methodology: Items were generated through literature review, interviews with parents of people with DS and professional experts and through frequency testing. Data were gathered from one population-based and two clinic-based samples for the separate aspects of validation. Validation consisted of evaluation of: i) internal reliability of the domain structure through Cronbach's alpha; ii) criterion validity against clinical indicators and a clinician's evaluation of some items; iii) construct validity involving an age-matched comparison of domain scores between people with DS and non-DS siblings, and within the DS group by health status indicators; and iv) test-retest reliability through the generation of intra-class correlation coefficients (ICC).
Results: A 20-item instrument with four domains (communication, eating, parafunction and symptoms) was developed. Cronbach's alpha by domain was 0.5-0.8. Indicators of criterion validity for domains against clinical indicators (Spearman's coefficient 0.1-0.4) and parent-rated items against clinician-rated items (weighted Kappa 0.1-0.8) were varied as anticipated. Indicators of construct validity (differences with non-DS siblings and correlations with medical status within the DS group) were excellent. Test-retest reliability was good (ICC range 0.64-0.84).
Conclusion: These data suggest the test instrument is valid as a descriptive, discriminative, proxy English language measure of oral health problems in people with DS aged four years or more.