Background: The Edmonton Symptom Assessment Scale (ESAS) is a nine-item patient-rated symptom visual analogue scale developed for use in assessing the symptoms of patients receiving palliative care. The purpose of this study was to validate the ESAS in a different population of patients.
Methods: In this prospective study, 240 patients with a diagnosis of cancer completed the ESAS, the Memorial Symptom Assessment Scale (MSAS), and the Functional Assessment Cancer Therapy (FACT) survey, and also had their Karnofsky performance status (KPS) assessed. An additional 42 patients participated in a test-retest study.
Results: The ESAS "distress" score correlated most closely with physical symptom subscales in the FACT and the MSAS and with KPS. The ESAS individual item and summary scores showed good internal consistency and correlated appropriately with corresponding measures from the FACT and MSAS instruments. Individual items between the instruments correlated well. Pain ratings in the ESAS, MSAS, and FACT correlated best with the "worst-pain" item of the Brief Pain Inventory (BPI). Test-retest evaluation showed very good correlation at 2 days and a somewhat smaller but significant correlation at 1 week. A 30-mm visual analogue scale cutoff point did not uniformly distinguish severity of symptoms for different symptoms.
Conclusions: For this population, the ESAS was a valid instrument; test-retest validity was better at 2 days than at 1 week. The ESAS "distress" score tends to reflect physical well-being. The use of a 30-mm cutoff point on visual analogue scales to identify severe symptoms may not always apply to symptoms other than pain.