Unjustified use of the Quality of Well-Being Scale in priority setting in Oregon

The Quality of Well-Being Scale (QWB) is an instrument for valuing health states on a continuum from unity (healthy) to zero (dead). While it seems safe to assume that the values have ordinal properties, there is neither theoretical nor empirical basis for claiming that they have the cardinal properties that are required in calculations of social benefit in cost-utility analysis. Failure to recognize this led the Oregon Health Services Commission to produce a QWB-based priority list with a number of counterintuitive rankings. A set of health state values based on upper end compression would have produced a list more in accordance with public preferences.