Introduction Postoperative pain (POP) represents a major challenge in the management of surgical patients, as it is highly common after major surgeries and is associated with increased morbidity and mortality. POP and its impact on patients who underwent liver transplantation (LT) is poorly understood. Aim This study was undertaken to investigate the incidence, assessment of POP, and clinical outcomes of patients with high level of postoperative pain in LT. Materials and methods After IRB approval, adult LT patients between March 2013 and September 2015 at our center were retrospectively reviewed. All patients who were extubated in the first week following LT were included. Pain score (0 to 10) during the first seven days post-extubation was assessed by numerical rating scale and recorded. Patients were divided into two groups: postoperative low to moderate pain score (PLMPS) reported pain score from (0-6) and postoperative high pain score (PHPS) from (7-10). The two groups were compared using univariate analysis and independent risk factors were identified by multivariate logistic regression. Of 424 patients who underwent LT during this period, 272 were extubated within the first postoperative week and were included in the analysis. Results A total of 114 (41.9%) patients reported pain score at 7 or higher during 7 days following extubation and 158 patients (58.1%) reported pain score "between 0 to 6" during the same period. There were no significant differences regarding to age, gender, MELD score, surgery time, intraoperative blood transfusion, vasopressor use and renal replacement therapy between the PLMPS and PHPS groups. However, patients in the PHPS group had a higher dose of hydromorphone (6.2±7.1 vs. 3.4±4.3, p=0.001), oral morphine equivalent (233.9±302.7 vs 132.6±309.8, p=0.008), and longer hospital stay after LT compared with those in the PLMPS group (44.2±46.3 days vs 30.7± 26.6, p=0.006). Using multivariate logistic regression analysis, PHPS was independent risk factor for prolonged (>30 days) hospital stay after LT (OR 2.0 95% CI 1.04-3.83, p=0.04). Other independent risk factors for prolonged hospital stay after LT include preoperative encephalopathy, renal replacement therapy, and graft failure. Conclusion PHPS was reported to affect 41.9% of adult LT patients. Patients with PHPS had high doses of hydromorphone, oral morphine equivalent andprolonged hospital stay after LT than patients with PLMPS. Out findings, highlight the importance of pain incidence, assessment and management after LT. Abbreviations: POP, postoperative pain; OLT, orthotopic liver transplantation; LT, liver transplantation; PHPS, postoperative high pain score; PLMPS, postoperative low to moderate pain score; OME, oral morphine equivalent; CI, confidence interval; OR, odds ratio; MELD, model for end-stage liver disease; UCLA, University of California, Los Angeles.
