The Edmonton Symptom Assessment System, a proposed tool for distress screening in cancer patients: development and refinement

The Edmonton Symptom Assessment System (ESAS) has been proposed as one element of a distress screening strategy in cancer patients. It consists of 11-point numerical rating scales for self-report of nine common symptoms of cancer, with a 10th scale for a patient-specific symptom. The ESAS has undergone widespread adoption internationally for clinical, research and administrative purposes. Despite its rapid uptake, validity evidence has lagged behind, and concerns have been raised about feasibility and usefulness. The objective of this paper is to provide a synthesis of a program of research focusing on the psychometric properties of the ESAS.We describe and discuss a series of three ESAS studies undertaken by our group: (i) a review of ESAS validation studies (1991-2006); (ii) a think-aloud study conducted in 20 advanced cancer patients; and (iii) a prospective multicenter study conducted in 160 patients in different palliative care settings, comparing the ESAS with a revised version (ESAS-r).The review identified 13 articles focusing on gathering reliability and/or validity evidence; the need to standardize the ESAS and conduct further validation research was apparent. The think-aloud study elucidated the complex cognitive processes by which patients arrive at symptom ratings and areas of potential difficulty in understanding and completing the ESAS. The multicenter study demonstrated that the ESAS-r was significantly easier for patients to understand.Overall, our findings support consideration of the ESAS and its successor, the ESAS-r, for use in distress screening in cancer patients. Areas for future research will be presented. Copyright © 2011 John Wiley & Sons, Ltd.