Methodologic challenges in the development of utility measures of health-related quality of life in rheumatoid arthritis.

Utility measures of health-related quality-of-life (HRQL) are unique in that they focus on patient preferences for alternative health conditions and combine benefit and toxicity into one number. This paper addresses the application of utility measurement techniques to assess HRQL in rheumatoid arthritis (RA). More specifically, the measurement issues and empirical evaluation strategies relevant to establishing the usefulness of utility measures in clinical trials and "n of 1" studies in RA are presented. First, utilities are reviewed within the context of RA and the other measures of benefit and toxicity currently in use. Second, the key methodologic challenges relevant to the development of HRQL measures of RA treatment impact are identified. Finally, a new utility instrument suitable for use in both parallel group and "n of 1" drug trials in RA is presented. The work described also addresses the interpretation of utility values and hence their acceptability to clinicians, researchers and policy makers and may aid initiatives to establish HRQL as one of the criteria for approval by federal drug regulatory agencies. Given that patient preferences constitute a central concept within the framework of HRQL, further empirical evaluation of utility measures of preference is fundamental to improving the HRQL measurement tool-kit.