Effect of Preemptive Acetaminophen on Opioid Consumption: A Meta-Analysis.

Background: Strategies for reducing postoperative opioid consumption have been explored in many recent studies, due in large part to the recent opioid epidemic. Preemptive analgesia has been proposed as a potential method, but its use is still controversial.

Objectives: This review aimed to evaluate the efficacy of a single dose of acetaminophen as preemptive analgesia for patients undergoing general anesthesia.

Study Design: A meta-analysis of randomized controlled trials (RCTs).

Setting: The electronic databases of PubMed, EMBASE, Cochrane Library, and the Web of Science were searched. The protocol was previously registered in the PROSPERO database under the registration number CRD 42020165634.

Methods: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. RCTs that compared preemptive acetaminophen with placebo in surgical patients receiving general anesthesia were included. The risk of bias for each included study was independently assessed using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions.

Results: Six studies with 563 patients were included. Overall, the studies showed a reduction in 24-hour opioid consumption (standardized mean difference [SMD], -1.45; 95% confidence interval [CI], -2.36 to -0.55; P = 0.002), pain scores at 12 hours postoperatively (SMD, -0.86; 95% CI, -1.25 to -0.48; P < 0.0001), and a lower incidence of postoperative nausea (risk ratio [RR] 0.45; 95% CI, 0.34-0.58; P < 0.001) and vomiting (RR 0.39; 95% CI, 0.22-0.72; P = 0.002).

Limitations: The major limitation of this meta-analysis relates to the risk of bias in the limited number of included studies.

Conclusions: Preemptive acetaminophen administration significantly reduces opioid consumption within the initial 24 hours following general anesthesia, with lower pain scores at 12 hours after surgery, and less nausea and vomiting. However, well-conducted RCTs are still needed.