Comparison of direct and indirect methods of estimating health state utilities for resource allocation: review and empirical analysis

doi:10.1136/bmj.b2688

Published 22 July 2009, doi:10.1136/bmj.b2688
Cite this as: BMJ 2009;339:b2688

Research

Comparison of direct and indirect methods of estimating health state utilities for resource allocation: review and empirical analysis

David Arnold, medical student¹, Alan Girling, senior research fellow², Andrew Stevens, professor of public health², Richard Lilford, professor of clinical epidemiology²

¹ Cardiff University Medical School, Cardiff, ² School of Health and Population Sciences, University of Birmingham, Birmingham B15 2TT

Correspondence to: R Lilford r.j.lilford{at}bham.ac.uk

Background and objective Utilities (values representing preferences)for healthcare priority setting are typically obtained indirectlyby asking patients to fill in a quality of life questionnaireand then converting the results to a utility using populationvalues. We compared such utilities with those obtained directlyfrom patients or the public.

Design Review of studies providing both a direct and indirectutility estimate.

Selection criteria Papers reporting comparisons of utilitiesobtained directly (standard gamble or time trade off) or indirectly(European quality of life 5D [EQ-5D], short form 6D [SF-6D],or health utilities index [HUI]) from the same patient.

Data sources PubMed and Tufts database of utilities.

Statistical methods Sign test for paired comparisons betweendirect and indirect utilities; least squares regression to describeaverage relations between the different methods.

Main outcome measures Mean utility scores (or median if meansunavailable) for each method, and differences in mean (median)scores between direct and indirect methods.

Results We found 32 studies yielding 83 instances where directand indirect methods could be compared for health states experiencedby adults. The direct methods used were standard gamble in 57cases and time trade off in 60 (34 used both); the indirectmethods were EQ-5D (67 cases), SF-6D (13), HUI-2 (5), and HUI-3(37). Mean utility values were 0.81 (standard gamble) and 0.77(time trade off) for the direct methods; for the indirect methods:0.59 (EQ-5D), 0.63 (SF-6D), 0.75 (HUI-2) and 0.68 (HUI-3).

Discussion Direct methods of estimating utilities tend to resultin higher health ratings than the more widely used indirectmethods, and the difference can be substantial. Use of indirectmethods could have important implications for decisions aboutresource allocation: for example, non-lifesaving treatmentsare relatively more favoured in comparison with lifesaving interventionsthan when using direct methods.

© Arnold et al 2009
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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