Background: Opioids are known to induce delirium, but few studies have closely investigated differences in incidence of delirium among different opioids.
Objectives: To determine whether there is a clinically significant difference in the incidence of delirium between oral opioids in previously opioid-naive patients.
Methods: Subjects were 259 opioid-naive in-patients with cancer who were started on morphine sulfate, oxycodone hydrochloride, or tapentadol hydrochloride extended-release tablets at our hospital between August 1, 2014, and September 30, 2018. The incidence of delirium during the first week of treatment was compared between the drugs.
Results: The incidence of delirium was 4.8% (n = 83) for morphine sulfate, 6.9% (n = 131) for oxycodone hydrochloride, and 6.7% (n = 45) for tapentadol hydrochloride. The incidence did not significantly differ between oxycodone hydrochloride (OR = .69, 95% CI = .20-2.30, P [Fisher's exact test] = .77) or tapentadol hydrochloride (OR = .71, 95% CI = .15-3.32, P [Fisher's exact test] = .70) and morphine sulfate (reference group). Moreover, the incidence did not significantly differ between tapentadol hydrochloride (OR = 1.03, 95% CI = .27-3.00, P [Fisher's exact test] = 1.00) and oxycodone hydrochloride (reference group).
Conclusion: The incidence of delirium in previously opioid-naive patients did not differ significantly among morphine sulfate, oxycodone hydrochloride, and tapentadol hydrochloride extended-release tablets, suggesting similar risk of delirium in opioid-naive patients among these oral opioids.
Keywords: concomitant drugs; delirium; morphine; oral opioids; oxycodone; tapentadol.