Mapping for economic evaluation.

INTRODUCTION/
BACKGROUND: Mapping provides a statistical algorithm that allows the estimation of utilities and consequently calculation of QALYs in clinical studies where preference-based measures are not implemented. SOURCES OF DATA: Reviews of the mapping literature were utilized. AREAS OF AGREEMENT: Mapping requires similar populations between the estimation and study data sets, with a high degree of overlap between the target and base measures being desirable. The National Institute for Health and Clinical Excellence recognizes mapping as a method to provide utility information. Areas of controversy Issues surrounding mapping include the descriptive system of the measure, the appropriate econometric method and model specification. GROWING POINTS: There is a need for further research into the issue of over-prediction for severe health states and uncertainty around the estimated utility scores. AREAS TIMELY FOR DEVELOPING RESEARCH: Mapping continues to be an important area of research for economic evaluation, in particular validation of mapping functions.