Abstract
Dear Editor:
I read the article by Miwa et al. 1 on terminal dyspnea with appreciation for its pragmatic multicenter design and its inclusion of patients in the last days of life—an often understudied population. The work meaningfully contributes to the evidence base on opioid use for breathlessness and, importantly, to the discussion of feasible outcome assessment near the end of life.
I offer several comments to support interpretation and future work.
First, while dyspnea improvement is reported across prognostic groups, the acquisition rate of the Numerical Rating Scale in the “days” group declined to about 55% at 72 hours. This suggests substantial and likely nonrandom missingness. Patients able to self-report may therefore represent a selected subgroup, potentially biasing estimates of opioid benefit upward in the “days” cohort.
Second, I agree that the Integrated Palliative Care Outcome Scale is a valuable proxy when patient-reported outcomes are not feasible. However, given its ordinal structure, complementary analyses (e.g., ordinal models, nonparametric summaries, or responder-based endpoints) could strengthen inference and improve clinical interpretability.
Third, despite statistically significant improvements, a considerable proportion of patients (approximately 40%–60%) continued to experience moderate to severe dyspnea after 72 hours. These results may be best framed as partial relief, with a substantial residual symptom burden—particularly in patients with a prognosis of days.
Finally, the increased incidence of somnolence and delirium in the “days” group is clinically important, yet confounding by the dying process and concurrent medications is likely. Sensitivity analyses accounting for baseline neurocognitive status and sedating comedications could help contextualize these findings.
I congratulate the authors on addressing a complex and clinically crucial symptom and for advancing the discussion on how best to measure breathlessness when patient self-report is no longer feasible. We hope these remarks contribute constructively to ongoing research aimed at refining assessment strategies and optimizing care for terminal breathlessness.