Efficacy and safety of patient-controlled opioid analgesia for acute postoperative pain - A quantitative systematic review

Background: The usefulness of intravenous patient-controlled analgesia (PCA ) with opioids for postoperative analgesia is not well defined. Methods: We systematically searched (MEDLINE, EMBASE, Cochrane Library, bib liographies, any language, to January 2000) for randomised trials comparing opioid-based PCA with the same opioid given intramuscularly, intravenously , or subcutaneously. Weighted mean differences (WMD) for continuous data, r elative risks (RR) and numbers-needed-to-treat (NNT) for dichotomous data w ere calculated with 95% confidence intervals (CI) using fixed and random ef fects models. Results: Data from 32 trials were analysed: 22 (1139 patients) were with mo rphine, five (682) with pethidine, three (184) with piritramide, one (47) w ith nalbuphine and one (20) with tramadol. In three morphine and one pethid ine trial (352 patients), more patients preferred PCA (89.7% vs 65.8%, RR 1 .41 (95%CI 1.11 to 1.80), NNT 4.2). Combined dichotomous data on pain inten sity and relief, and the need for rescue analgesics from eight morphine, on e pethidine, one piritramide, and one nalbuphine trial (691 patients), were in favour of PCA (RR 1.22 (1.00 to 1.50), NNT 8). In two morphine trials ( 152), pulmonary complications were more frequently prevented with PCA (100% vs 93.3%, RR 1.07 (1.01 to 1.14), NNT 15). There was equivalence for cumul ative opioid consumption, pain scores, duration of hospital stay, and opioi d-related adverse effects. Conclusion: These trials provide some evidence that in the postoperative pa in setting, PCA with opioids, compared with conventional opioid treatment, improve analgesia and decrease the risk of pulmonary complications, and tha t patients prefer them.