Oral oxycodone offers equivalent analgesia to intravenous patient-controlled analgesia after total hip replacement: a randomized, single-centre, non-blinded, non-inferiority study

Background. To determine if oral oxycodone (OOXY) could provide equivalent postoperative analgesia and a similar side-effect profile to i.v. patient-controlled morphine in patients undergoing elective primary total hip replacement (THR) under spinal anaesthesia. Methods. We studied 110 consecutive patients aged 60-85 yr. After operation, patients were randomly allocated to receive either oral controlled-and immediate-release OOXY or i.v. patient-controlled analgesia (IVPCA) with morphine. Both groups received regular co-analgesia and antiemetics. The primary outcome measures were: (i) postoperative pain at rest and movement and (ii) nausea score recorded 12 hourly. The secondary outcome measures were: (i) time to first mobilization, (ii) total amount of opioid consumed, (iii) number of additional antiemetic doses, and (iv) time to analgesic discontinuation. Results. There were no statistically significant differences in the primary outcome measures of pain at rest and movement (P > 0.05, 95% confidence intervals -0.41, +0.96) or nausea score (P > 0.5). The secondary outcome measures showed no significant difference in the total amount of opioid consumed (102 vs 63 mg; P > 0.05) or time to mobilization (24.45 vs 26.6 h, P=0.2). The number of antiemetic doses required in the first 24 h was significantly lower in the OOXY group (1.1 vs 1.4, P < 0.05). The time to analgesic discontinuation was significantly shorter in the OOXY group (50.5 vs 56.6 h, P < 0.05). Oral analgesia with OOXY was approximately GBP 10 less expensive per patient than IVPCA. Conclusions. Oral analgesia with OOXY after THR offers non-inferior analgesia to IVPCA and may offer some logistical and cost advantages.