Performance status assessment among oncology patients: a review.

Performance status is a global assessment of a patient's ability for self-care and ambulation. It is an important and widely used prognostic variable for patients with cancer. Several different scales to assess performance status are in use, and scale scores are used for a variety of purposes, including patient selection and stratification for cancer clinical trials. New uses for life quality evaluations have also been proposed. Despite the widespread use of the scales, little information is available about the reliability and validity of these measures. Improved and extended application of these scales requires that several types of data about measurement properties of the scales be collected and analyzed. Various issues related to the measurement properties of the scales and their implications for oncology need to be understood to best develop their use.