"The trouble with QALYs...".

This paper summarises the use of QALYs in evaluating changes in mental health states, highlighting the benefits and challenges of their use in this field. The general principles underlying the QALY measure and the most common methods of measuring QALYs are discussed briefly. Evidence of the usefulness and problems of using this generic measure of health-related quality of life are provided from a sample of recent studies relating to depression, schizophrenia, attention deficit hyperactivity disorder and dementia. In each case, attempts were made to use QALYs to measure changes in health states. While in principle, the QALY is enormously attractive, its suitability for measuring changes in many mental health conditions remains open to doubt as existing tools for generating QALY scores such as the EQ-5D have tended not to perform sufficiently well in reflecting changes in many mental health states. New developmental work is needed to construct better QALY-measuring tools for use in the mental health field. Both the conceptualisation and measurement of QALYs need to be built on a valid, comprehensive model of quality of life specific to a mental health disorder, to ensure that the resultant tool is sensitive enough to pick up changes that would be expected and seen as relevant in the course of the illness.