This study was conducted in the Paediatric Dentistry Department at St Thomas’ Hospital, London and approved by NHS research ethics, namely HRA and Health and Care Research Wales (HCRW) (REC reference 19/NS/0164). Participants were provided with an invitation letter and an information leaflet regarding the study, and a written consent form was signed by the parent/carer if they agreed to participate. Consent was voluntary and participation was on an opt-in basis only. The participant could withdraw consent at any time.
The study aimed to recruit 50 parents/carers of children from those who were referred to the new patient assessment clinic. To avoid selection bias, all eligible parents/carers were approached on the clinic. The following exclusion criteria were applied: the child referred was under 3 or over 16 years of age; the child had medical problems, hypodontia (missing teeth) or had cFPMs which required extraction; the parent had insufficient knowledge of English. These exclusions were applied to avoid the influence that certain medical and dental conditions might have on participant’s values. Parents of children with cFPMs were excluded, to avoid the influence this questionnaire may have had on their treatment preferences for their child’s cFPMs.
The questionnaire comprised an introduction, a ranking exercise, questions eliciting preferences using VAS and TTO and questions on demographics. Guidance was followed on the development of questionnaires for eliciting preferences over health states (15). The questionnaire was piloted for content and face validity among colleagues and patients. The questionnaire and associated consent material were shown to several parents attending the Paediatric Dentistry clinic. Patient feedback was considered regarding their layout and content. The Gunning Fog Index was used to ensure appropriate readability. The reading age for the study documents ranged from age 7 – 10 years. Parents found the study documents easy to read and found the layout acceptable. Regarding the questionnaire, one parent found ‘some of it a little complicated’. One parent stated that they had to ‘read it a few times before they could understand it’. Following this feedback, we ensured that the researcher would be available to help participants if they had any questions.
Eight health states were valued in the questionnaire representing the most common outcomes of either restoring or extracting a cFPM over the long term:
- White filling
- Silver crown
- Root canal treatment and crown
- Open gap (tooth missing)
- Closed gap (tooth missing)
- Extraction and bridge
- Extraction and implant
- Extraction and denture.
The reader is directed to the original questionnaire in Additional File 1 for a brief description of the eight health states.
Ranking exercise
Participants were asked to imagine if they had a cFPM. Different treatment options were presented in a table with an explanation of each treatment option. The participant was asked to rank these treatment options from 1 (most preferred option) to 8 (least preferred option).
VAS method
Participants were asked to think about the same treatment options. For each option, the participant was asked to rate it on a 100mm scale from 0 to 100. The ends of the scale were labelled as the worst possible outcome and the best possible outcome.
TTO method
The participant was presented with a choice between a traditional treatment outcome and a hypothetical treatment that would result in a perfectly healthy tooth but with reduced longevity. The traditional treatment option would last for 10 years, after which any tooth or restoration would be removed, and a gap would remain. The hypothetical treatment would last for less than ten years after which the tooth would be removed and a gap would remain. Each participant was asked how many years (out of 10 years) with a ‘perfect tooth’ followed by a gap would be equivalent to the traditional treatment option.
The questionnaire concluded with questions on age, gender, ethnic background, employment status and partial postcode. The questionnaire took approximately 10 minutes to complete. The parent completed the questionnaire after the child’s dental appointment. Questionnaires were administered with guidance and support from the researcher to help ensure respondents understood the tasks and to promote engagement with the survey.
Statistical Analysis
Response data were summarised as means, medians, standard deviations, and inter quartile range of scores. The response data was checked for normality using histograms. The data were skewed and therefore the relationship between demographic characteristics and responses were examined using either the Mann Whitney U test or the Kruskal Wallis test, with significance set at p<0.05. Since this was an exploratory analysis no adjustment was made for multiple testing. Weighted kappa was used to assess the agreement between the ranking, VAS and TTO responses. All statistical analysis of the data was carried out using Stata version 16® and Excel®.