The reliability of two methods of utility assessment in dentistry

Objective The objective of this study was to investigate the modification o f two utility assessment techniques (visual analogue scale and daily time t rade-off) used in medicine to the dental setting, with a focus on their tes t-retest reliability and ease of use. Basic research design The study invol ved a postal questionnaire survey which incorporated a dental visual analog ue scale (DVAS) to assess utility values for 12 specified tooth states, and a specifically designed instrument, the dental freetime trade-off (DFTO) t o assess utility of the participants' current dental health state. Particip ants A total of 582 regularly attending adolescent dental patients were sen t the questionnaire. A further 100 of those who fully completed the relevan t sections of the questionnaire were sent a repeat questionnaire to facilit ate assessment of test-retest reliability. Results A final response rate of 74.7% was achieved with the mean age of respondents being 17 years. Fifty per cent of those sent a repeat questionnaire for the purposes of reliabili ty assessment returned the questionnaire. Test-retest reliability of both u tility assessment techniques appeared acceptable. Spearman correlation coef ficients for the dental freetime trade-off (DFTO) and the dental visual ana logue scale (DVAS) were (0.67 and 0.83 respectively. Promising results, in terms of utility values, were elicited from the DVAS whilst utility values elicited using the DFTO were highly skewed. Conclusions The newly developed modification to the daily time trade-off technique, the DFTO, showed a goo d level of test-retest reliability and ease of completion although the high ly skewed utility results produced may indicate a design flaw. The DVAS how ever, appears to show promise, in terms of test-retest reliability, ease of completion and resultant utility values.