Prevalence of opioid-induced adverse events across opioids commonly used for analgesic treatment in Japan: a multicenter prospective longitudinal study

Purpose Although opioids have been shown to be effective for cancer pain, opioid-induced adverse events (AEs) are common. To date, little is known about the differences in risks of AEs by opioid type. This study was performed to compare the prevalence of AEs across opioids commonly used for analgesic treatment in Japan. Methods This study was conducted as a preplanned secondary analysis of a multicenter prospective longitudinal study of inpatients with cancer pain who received specialized palliative care for cancer pain relief. We assessed daily AEs until termination of follow-up. We rated the severity of AEs based on the Common Terminology Criteria for Adverse Events version 5.0. We computed adjusted odds ratios for each AE (constipation, nausea and vomiting, delirium, and drowsiness) with the following variables: opioid, age, sex, renal dysfunction, and primary cancer site. Results In total, 465 patients were analyzed. Based on the descriptive analysis, the top four most commonly used opioids were included in the analysis: oxycodone, hydromorphone, fentanyl, and tramadol. With respect to the prevalence of AEs among all analyzed patients, delirium ( n = 25, 6.3%) was the most frequent, followed by drowsiness ( n = 21, 5.3%), nausea and vomiting ( n = 19, 4.8%), and constipation ( n = 28, 4.6%). The multivariate logistic analysis showed that no single opioid was identified as a statistically significant independent predictor of any AE. Conclusion There was no significant difference in the prevalence of AEs among oxycodone, fentanyl, hydromorphone, and tramadol, which are commonly used for analgesic treatment in Japan.