Is there a case for using visual analogue scale valuations in cost-utility analysis?
This paper critically reviews theoretical and empirical propositions regarding visual analogue scale (VAS) valuations of health states and their use in cost-utility analysis (CUA). A widely repeated assertion in the economic evaluation literature is the inferiority, on theoretical grounds, of VAS valuations. Five common criticisms are: VAS lacks a theoretical foundation; VAS values are not 'choice based'; VAS values are not consistent with utility-under-uncertainty requirements; context and range effects observed in VAS valuation data mean that they cannot even be considered to represent measurable value functions; and when completing a VAS, people are not trying to express values. We address each of these points: the VAS does have a theoretical basis, being entirely consistent with the non-welfarist foundations of QALYs and CUA; the 'choiceless' nature of the VAS is incorrectly judged by stated preference criteria relevant to monetary rather than health state valuations, and VAS valuations do in any case involve an element of choice; because valuations are intended for use in social decision-making, it may be advantageous that VAS values are elicited under conditions of certainty; although there are measurement problems with the VAS, means such as better design and transformations of data can deal with these; and with any method of eliciting values, it is unrealistic to expect people consciously to think in terms of social science constructs such as utilities.Moreover, there are problems, both theoretical and empirical, with alternative methods. Selection of the appropriate valuation method should be based on empirical performance, and in this the VAS has important advantages. We conclude that there are strong grounds for disputing the consensus view against the VAS and challenge those who hold it to deploy more convincing arguments and evidence in favour of alternative methods. However, we identify areas where further research is required to establish and consolidate the potential of the VAS as a valuation method.
City Health Economics Centre, City University, London, UK. d.parkin@city.ac.uk
David
D
Parkin
Nancy
N
Devlin
D003365:Costs and Cost Analysis / Q000379:methods; D006304:Health Status; D006801:Humans; D010147:Pain Measurement / Q000706:statistics & numerical data*; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D006113:United Kingdom