Use of quality of life measures in clinical trials.

To be useful in clinical trials, quality of life (QOL) measures must meet basic criteria related to psychometric properties (reliability, validity, and sensitivity), length and acceptability to patients, and availability of parallel child and proxy versions. This paper examines the adequacy of several current measures, with special reference to childhood cancer. We identified 10 such measures of varying length, age-appropriateness, and content. We also discerned a number of obstacles to inclusion of QOL measures in trials. These include clinician bias, financial cost, and time required to inform families and to obtain informed consent from parents. We noted some methodological difficulties associated with measuring QOL over time. These include allowing for maturation and accounting for response shift, or children's propensity to change their internal standards for assessing QOL.