Providing an extended use of an otological-specific outcome instrument to derive cost-effectiveness estimates of treatment.

OBJECTIVES: Although Quality-Adjusted Life Years (QALYs) are increasingly being used by decision makers to make comparisons of cost-effectiveness, there are no otological-specific outcome measures that fit within this QALY framework. This study had two main objectives. The first was to provide a means to derive QALYs from a condition-specific otological instrument (COQOL) and the second, was to assess the convergent validity, or degree of correlation, between the COQOL and SF-6D, an established QALY instrument. DESIGN: Longitudinal cohort study designed to assess the convergent validity between SF-6D and COQOL, and to generate a mapping function to enable SF-6D values to be predicted from the COQOL responses. SETTING: Cambridge University Hospital, UK. PARTICIPANTS: 207 patients attending a routine outpatient general otology clinic. MAIN OUTCOME MEASURES: SF-6D and the COQOL instrument completed at baseline, and again 3 months later. RESULTS: Convergent validity was demonstrated with mean SF-6D values decreasing linearly with increasing severity on the COQOL instrument. Overall, the correlation between the COQOL scores and the SF-6D values was moderate and statistically significant (r=.490, p=