Oxycodone vs Remifentanil for Analgesia in Mechanically Ventilated ICU Patients: Retrospective Review of Medical Records for Delirium Incidence and Duration.

Background: Delirium occurs in 45-80% of mechanically ventilated ICU patients and significantly worsens clinical outcomes. The impact of opioid analgesic selection on delirium risk remains unclear. We aimed to examine the association of oxycodone-based versus remifentanil-based analgesia with delirium incidence and duration in mechanically ventilated ICU patients. Methods: This single-center retrospective review of medical records included adults requiring invasive mechanical ventilation for >24 hours at a tertiary ICU in Suzhou, China (January-December 2025). Patients received oxycodone (n = 186) or remifentanil (n = 253) as the primary analgesic, as selected by the attending intensivist rather than by random assignment. Delirium was assessed twice daily via the Confusion Assessment Method for the ICU (CAM-ICU). Primary outcomes were delirium incidence and, among patients who developed delirium, delirium duration. Multivariable logistic regression, competing-risk analysis, and propensity score matching were applied to control for confounders; mechanical ventilation duration and ICU length of stay were prespecified as secondary, exploratory outcomes. Results: Among 439 patients (mean age 63.0 years; 61.0% male), oxycodone-based analgesia was associated with a lower observed delirium incidence (32.8% vs 48.6%; adjusted OR, 0.54; 95% CI, 0.36-0.80; P =0.002) and, among patients who developed delirium, a shorter delirium duration (median 2.20 vs 3.30 days; P <0.001). In unadjusted exploratory analyses, oxycodone was also associated with shorter mechanical ventilation duration (92.45 vs 127.00 hours; P <0.001) and ICU length of stay (8.60 vs 9.90 days; P =0.001). Mortality was comparable between groups (11.8% vs 11.5%). Constipation was more frequent with oxycodone (23.7% vs 15.8%); the study was not powered to establish equivalence or noninferiority for mortality or adverse events. Conclusion: In this single-center retrospective review of medical records, oxycodone-based analgesia was associated with a lower observed incidence of delirium and shorter delirium duration among patients who developed delirium compared with remifentanil-based analgesia. Given the nonrandomized treatment assignment, between-group differences in sedation depth and pain control, and the potential for residual confounding, these findings should be considered hypothesis-generating. Prospective studies using protocolized, equianalgesic treatment strategies are required before conclusions regarding comparative effectiveness or safety can be drawn.