OBJECTIVES: Economic evaluation of health services frequently requires using utility-based data to measure effectiveness. In instances where such data have not been collected but information on non-utility measures of quality of life is available, mapping from the latter to the former is accepted as a way of generating utilities. Several sleep-specific instruments used in economic evaluations are predominantly diagnostic tools, and not strictly quality-of-life measures. Others have a very narrow coverage of quality-of-life concepts. It is unknown whether such instruments can be adequately mapped onto utilities and, if so, which ones perform best. This study seeks to inform the ongoing debate through an extensive multi-instrument mapping exercise.

METHODS: Data on 1510 individuals from the Australian general population were analysed. Four statistical techniques were utilized to estimate Assessment of Quality of Life 4 Dimensions (AQoL-4D), EuroQoL 5 Dimensions 5-Level (EQ-5D-5L), Short-Form 6 Dimensions (SF-6D) and ICEPop CAPability measure for Adults (ICECAP-A) utilities derived from 6 sleep-specific instruments: Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), Functional Outcomes of Sleep Questionnaire (FOSQ), Pittsburgh Sleep Quality Index, Sleep Condition Indicator (SCI) and Flinders Fatigue Scale (FFS). K-fold validation was used to evaluate the predictive accuracy of 288 regression models using six criteria: mean absolute error (MAE), root mean squared error (RMSE), correlation, distribution of predicted utilities, distribution of residuals, and the proportion of predictions with absolute errors < 0.05.

RESULTS: Predictive-ability indices of the best-performing models were within acceptable ranges of published estimates. Best results were obtained when mapping onto SF6D and ICECAP-A utilities from the FFS, SCI and FOSQ. Mapping onto the AQoL-4D from the ESS and ISI yielded the worst predictive algorithms and lowest correlations.

CONCLUSIONS: These results suggest that, despite their widespread use in sleep economic evaluations, diagnostic tools like the ESS and ISI are unsuitable for mapping onto utilities.