Minimal clinically important differences in the Edmonton symptom assessment system in patients with advanced cancer

Abstract

Context: Longitudinal symptom monitoring is important in the setting of patients with advanced cancer. Scores over time may naturally fluctuate, although a patient may feel the same.

Objectives: The purpose of this study was to determine the minimal levels of change required to be clinically relevant (minimal clinically important difference [MCID]) using the Edmonton Symptom Assessment System (ESAS).

Methods: Between 1999 and 2009, patients completed the ESAS before palliative radiotherapy and at follow-up. MCIDs were calculated using both the anchor- and distribution-based methods for improvement and deterioration; 95% confidence intervals for the differences in mean change scores between adjacent categories also were calculated.

Results: A total of 276 patients completed the ESAS at baseline and during at least one follow-up visit. At the four-week follow-up, decrease of 1.2 and 1.1 units in pain and depression scales, respectively, constituted clinically relevant improvement, whereas increase of at least 1.4, 1.8, 1.1, 1.1, and 1.4 units, respectively, in pain, tiredness, depression, anxiety, and appetite loss items were required for deterioration. At the subsequent follow-ups, these values were similar. Overall, the MCID for improvement tended to be smaller than that for deterioration. The distribution-based method estimates tended to be larger than the 0.3 SD estimates, but closer to the 0.5 SD estimates.

Conclusion: MCIDs allow health care professionals to determine the success of treatment in improving the patient's quality of life. MCIDs may prompt health care professionals to intervene with new treatment. Future studies should confirm our findings with a variety of anchors.

Keywords: Edmonton Symptom Assessment System; Minimal clinically important difference; advanced cancer; palliative care.