The Efficacy of Acupuncture in Postoperative Pain Management: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis, conducted by Wu and colleagues in 2016, represents one of the most comprehensive evaluations of acupuncture for postoperative pain management. The study analyzed data from 13 randomized clinical trials involving 682 adult patients undergoing various types of surgery, ranging from abdominal procedures to cardiac and orthopedic operations. The research was motivated by the growing need for therapeutic alternatives to reduce dependence on opioid analgesics, which, although effective, are associated with significant side effects such as nausea, vomiting, sedation, and reduced intestinal motility. The methodology rigorously followed the PRISMA guidelines, with a systematic search of MEDLINE, the Cochrane Library, and EMBASE through September 2014.

Inclusion criteria were strict: only randomized controlled trials involving adults (18 years or older) who received acupuncture, electroacupuncture, or transcutaneous electrical nerve stimulation at acupoints (TENS) for acute postoperative pain. Studies using auriculotherapy were excluded due to methodological differences. The principal results demonstrated significant efficacy of acupuncture. On the first postoperative day, patients treated with acupuncture or related techniques showed lower pain intensity (mean difference: -1.27 points, 95% CI: -1.83 to -0.71, P<0.001) and lower opioid analgesic consumption (standardized mean difference: -0.72, 95% CI: -1.21 to -0.22, P=0.005) compared with control groups.

Sensitivity analysis using the leave-one-out method confirmed the robustness of the findings, indicating that the results did not depend on any single study. No publication bias was detected by the Egger test. Subgroup analyses revealed important differences between modalities. Conventional acupuncture was superior, reducing pain by 2.67 points (95% CI: -3.92 to -1.43, P<0.001), although it did not show a significant benefit in reducing opioid use.

TENS at acupoints was effective for both pain reduction (mean difference: -0.98, 95% CI: -1.81 to -0.15, P=0.020) and reduction in opioid consumption (P=0.001). Surprisingly, electroacupuncture did not demonstrate statistically significant superiority over control for pain reduction (P=0.116) or opioid use (P=0.142). Proposed mechanisms for acupuncture analgesia include the release of endogenous neuropeptides in the central nervous system, such as β-endorphins, enkephalins, and dynorphins, as well as the modulation of neurotransmitters such as serotonin, norepinephrine, and GABA. Stimulation of specific points may activate endogenous inhibitory pain pathways and facilitate self-healing mechanisms.

The clinical implications are substantial. The findings suggest that acupuncture may be a valuable adjunctive therapy in postoperative pain management, potentially reducing dependence on opioids and their associated adverse effects. This is particularly relevant in the current context of the opioid crisis and the search for multimodal approaches to pain control. However, the study has important limitations.

Heterogeneity in surgical types, acupuncture points, and control models may have influenced the results. The methodological quality of the included studies was considered moderate, with more than half presenting a high risk of detection bias due to inadequate allocation concealment and blinding. In addition, the analysis focused only on the first postoperative day, limiting understanding of long-term benefits. The study did not assess reduction in opioid side effects, a clinically relevant outcome.

Variation in pain measurement instruments (visual analog scale, numerical rating scale, and percentage of pain relief) may have affected some assessments. This meta-analysis provides robust evidence for the use of acupuncture as adjunctive therapy in postoperative pain management, particularly conventional acupuncture and TENS at acupoints. The results support integrating these modalities into postoperative recovery protocols, contributing to a more holistic and potentially safer approach to surgical pain control.