The 90% Minimum Effective Dose of Oxycodone for Thoracoscopic Lobectomy in Elderly Patients: A Double-Blind Study Using a Biased-Coin Design

Purpose: Postoperative pain significantly impairs recovery in elderly patients. Oxycodone is widely used in the postoperative period due to its favorable safety profile and low risk of respiratory depression. To determine the minimum effective dose of intravenous oxycodone, administered in combination with postoperative patient-controlled intravenous analgesia, that achieves at least 90% efficacy in elderly patients undergoing video-assisted thoracoscopic surgery. Patients and Methods: We enrolled participants aged 65 and older who underwent thoracoscopic lobectomy. Oxycodone was administered 30 minutes before the completion of the surgical procedure. The initial dose was 0.02 mg/kg. Subsequent dose adjustments were determined based on the previous patient’s response using a biased coin design. The dose interval was 0.01 mg/kg. A positive response was defined as an NRS score ≤ 3 at cough 2 hours postoperatively. The study was terminated after 45 successful responses. Secondary endpoints included postoperative pain assessed at various time points up to hospital discharge, adverse events, sedation levels, and the occurrence of chronic pain during the postoperative period. Results: A total of sixty patients were enrolled. Among elderly patients undergoing elective VATS with multimodal analgesia, the ED90 of oxycodone was 0.104 mg/kg (95% CI: 0.095– 0.108 mg/kg). The supplementary analysis focused on patients who received at least 0.09 mg/kg of oxycodone. After adjusting for imbalanced baseline characteristics, the incidence of chronic pain in the 0.09 mg/kg dose group was significantly higher than in the 0.10 mg/kg dose group (P = 0.007). Conclusion: For thoracoscopic lobectomy in elderly individuals aged > 65 years, the ED90 of oxycodone was 0.104 mg/kg (95% CI: 0.095– 0.108 mg/kg). Keywords: ED90, oxycodone, elderly, chronic pain, video-assisted thoracoscopic surgery