Measuring utility values for QALYs: two methodological issues.

Two methodological concerns in utility estimation, the development of health state descriptions (scenarios) and the interpretation of interval scale anchor points, are examined in the context of disease-specific cost utility analyses (CUA). It is contended that results in CUA can be fundamentally biased by: (i) how the information presented in a scenario is generated; and (ii) the researcher's 'definition' of anchor points, when these are used as bounds to the interval scale. A number of recommendations are made, in particular for a more explicit reporting of these issues in CUA, to facilitate greater consistency in the application of utility measurement techniques.