The development and assessment of a condition specific quality of life measure for patients with developmentally absent teeth

The aim of this study was to develop a condition specific quality of life measure for hypodontia patients. A structured three stage approach to the methodology was followed, based on the work of Hunt et al. (1986). This entailed the use of qualitative methods to identify relevant dimensions of patients' perceptions, the creation of items from the qualitative data and then testing the properties of the measure including readability, ease of administration, validity and reliability. Five focus groups were held with a total of twenty two participants to identify issues of importance to patients. The transcripts of the discussions were analysed to derive the themes of importance. The frequency of occurrence of themes was determined. Four broad themes were identified that informed the design of the sections of the questionnaire. The readability ofthe questionnaire was assessed using the Flesch Reading Ease Score and was found to have a value of 81, or a U.S. grade level 5 equivalent to a reading age of 10 years. The criterion validity was analysed by comparing seven items of the questionnaire with seven similarly worded items in the Child Perception Questionnaire (CPQ). The criterion validity was good for these seven items. The construct validity was tested using Principal Component analysis (PCA). This in general showed good construct validity for the four sections of the questionnaire. It highlighted a low level of construct validity for one question each in both the activities and appearance section of the questionnaire. Cronbach’s alpha was used to test internal consistency reliability and was shown to be good for both the overall questionnaire and the individual sections of the questionnaire. Test-retest reliability scores showed good agreement between responses at Tl and T2 for all four sections. This was tested using the Intra Class Correlation Coefficient and Bland and Altman method. A condition specific quality of life measure has been developed for use in hypodontia patients. It demonstrates acceptable levels of reliability and validity and can therefore be considered for use in future hypodontia research and audit.