Conflict of Interest Disclosures

Abstract

The sensitivity analysis suggests that a moderate effect size equates to a greater than 1-point change for many symptoms, with values around 1 equating to a small effect size, but the authors have not commented on this. Their findings were compared with other work that estimated the MCID of other components of the Edmonton Symptom Assessment Scale. Our group has calculated the MCID for chronic breathlessness for a standalone 0 to 10 numerical rating scale. The MCID of a change of 1 point on the breathlessness scale found by Hui et al is remarkably similar to the findings of our secondary analysis of data from 4 clinical trials of opioids for refractory breathlessness. Furthermore, because the MCID in Johnson et al was assessed by patient-anchored (blinded patient preference) and statistical distribution methods, we were able to determine that such a change would be both a moderate effect size and a difference that resulted in patient-led treatment choice. Our findings from the distribution method were remarkably similar to the estimate derived from Hui et al’s standard-error-of-measurement sensitivity analysis (an 11.3-mm moderate effect size for Johnson et al vs a 1.2-point change for 0.5 standard deviations for Hui et al). Although the patient population in Johnson et al’s study included people with cancer and noncancer life-limiting illnesses causing breathlessness, a pooled data analysis showed that etiology was not a predictor of response to breathlessness, and this MCID for chronic refractory breathlessness was relevant regardless of the underlying etiology; this is an important finding in itself. The MCID is important in both clinical and research practice. Methodological work that provides a nuanced understanding is crucial because of the flow-on effects of the findings on clinical trial design and even reimbursement decisions.