Efficacy of postoperative epidural analgesia: a meta-analysis

Whether epidural analgesia is a better method than parenteral opioids for postoperative pain control remains controversial.

To systematically review the efficacy of postoperative epidural analgesia vs parenteral opioids, the primary alternative technique.

Studies were identified primarily by searching the National Library of Medicine's PubMed database (1966 to April 25, 2002) and other sources for studies related to postoperative epidural analgesia.

Inclusion criteria were a comparison of epidural therapy vs parenteral opioids for postoperative analgesia, measurement of pain using a visual analog scale (VAS) or numeric rating scale, randomization of patients to either therapy, and adult patients (> or =18 years). A total of 1404 abstracts were identified, 100 of which met all inclusion criteria.

Each article was reviewed and data extracted from tables, text, or extrapolated from figures as needed. Weighted mean pain scores, weighted mean differences in pain score, and weighted incidences of complications were determined by using a fixed-effect model.

Epidural analgesia provided better postoperative analgesia compared with parenteral opioids (mean [SE], 19.40 mm [0.17] vs 29.40 mm [0.20] on the VAS; P<.001). When analyzed by postoperative day, epidural analgesia was better than parenteral opioids on each postoperative day (P<.001 for each day after surgery). For all types of surgery and pain assessments, all forms of epidural analgesia provided significantly better postoperative analgesia compared with parenteral opioid analgesia (P<.001 for all), with the exception of thoracic epidural analgesia vs opioids for rest pain after thoracic surgery (weighted mean difference, 0.6 mm; 95% confidence interval, -0.3 to 1.5 mm; P =.12). The complication rates were lower than expected for nausea or vomiting and pruritus but comparable with existing data for lower extremity motor block.

Epidural analgesia, regardless of analgesic agent, location of catheter placement, and type and time of pain assessment, provided better postoperative analgesia compared with parenteral opioids.