The use of condition specific outcome measures in economic appraisal.

Despite growing concern over the use of health utility measures in economic evaluations of health care programmes, economists have been reluctant to use the wealth of knowledge contained within studies using condition specific outcome measures (CSOMs). Problems with the measurement properties of many CSOMs means that the scope for their use in economic appraisal is extremely limited. This paper examines the potential uses of CSOMs in economics, namely: to provide valid descriptive material, to provide scales for comparing the effectiveness of interventions and to 'validate' the descriptive accuracy of economic measures of benefit. It is argued that valid descriptive information is essential for economic appraisal, no matter which method of evaluation is used. Generic measures have been criticised for being too narrow and insensitive to the consequences of specific conditions. CSOMs offer a rich source of information to produce quality adjusted life years (QALYs) but two potential methods, one of mapping health states from one scale to a QALY classification (such as Rosser), and the other, developing 'exchange rates' between scales are unsatisfactory. A more rigorous approach would necessitate a major research programme of revaluing existing CSOMs using preference based methods. Another interesting avenue of research would be to use the information from CSOMs to construct health scenarios for valuation. Given the current state of development of outcome measures, it seems advisable to use CSOMs alongside economic measures in trials. Such a strategy would help demonstrate the usefulness of economic measures to clinicians and to reconcile the two measures.