Effectiveness of opioid switching for dyspnea and its predictors in cancer patients: a single-center retrospective observational study

Background: Morphine is the most used opioid for dyspnea, but other opioids such as oxycodone and fentanyl are increasingly used, and opioid switching to these is sometimes undertaken. No studies have verified the effectiveness of opioid switching for relief of dyspnea. We retrospectively investigated the effectiveness of opioid switching for dyspnea and its predictors. Methods: All patients with opioid switching for dyspnea during hospitalization at Komaki City Hospital from January 2019 to August 2022 were included. Opioid switching was defined as a change to another opioid, and the assessment period for evaluating the effectiveness and adverse events of opioid switching was set as 1 week. Patients with Numeric Rating Scale or Japanese version of the Support Team Assessment Schedule reduction for dyspnea of at least 1, or with clear improvement based on medical records, were considered valid. Mitigating factors for dyspnea were identified using logistic regression analysis. Results: Of the 976 patients with opioid switching, 57 patients had opioid switching for relief of dyspnea. Of these, opioid switching was effective in 21 patients (36.8%). In a multivariate analysis, older patients (odds ratio: 5.52, 95% CI: 1.50-20.20, P < 0.01), short prognosis for post-opioid switching (odds ratio: 0.20, 95% CI: 0.04-0.87, P = 0.03) and cachexia (odds ratio: 0.12, 95% CI: 0.02-0.64, P < 0.01) were significantly associated with opioid switching effects for dyspnea. There were no serious adverse events after opioid switching. Conclusion: This study indicates that opioid switching for dyspnea may have some effect. Furthermore, opioid switching for dyspnea may be more effective in older patients and less effective in terminally ill patients or in those with cachexia.