Efficacy of Non-opioid Analgesics in the Management of Postoperative Pain After Major Abdominal Surgery: A Comprehensive Review and Meta-Analysis of Randomized Controlled Trials

Postoperative pain (POP) is one of the leading clinical challenges of patients undergoing major surgeries, including abdominal surgeries. Opioid analgesics are considered the gold standard for POP. However, their use is associated with a high incidence of adverse events, including nausea and vomiting, which has prompted clinicians to look for alternative regimens that are not opioid-based. This review aims to provide an overview of the existing evidence regarding the effectiveness of non-opioid analgesics (NOAs) in the management of POP in patients who have undergone major abdominal surgeries. A comprehensive search was conducted on four databases: Google Scholar, PubMed, CENTRAL, and Science Direct. The studies that met the inclusion criteria were then included in the review. The reported outcomes were pooled using the Review Manager software (RevMan 5.4, The Cochrane Collaboration, London, UK). The literature search identified 657 articles, among which 18 were included in the review according to the inclusion criteria. Our study found that the mean postoperative opioid consumption was significantly lower among individuals treated with non-opioid analgesics than with opioid analgesics SMD -1.88; 95% CI (-2.40, -1.36); p < 0.0001). Further analysis showed that the mean opioid consumption was also lower in those who received NSAIDs and other atypical analgesics (SMD -2.24; 95% CI (-2.94, -1.55); p < 0.00001) and (SMD -1.18; 95% CI (-2.18, -0.17); p = 0.02), respectively. However, in those who received paracetamol, the mean opioid consumption was comparable to that of controls (SMD -1.09; 95% CI (-2.21, 0.03); p = 0.06). Secondly, our study found that the incidence of opioid-related nausea was reduced in patients who received NOA than in controls (OR 0.38; 95% CI (0.22, 0.66); p = 0.0005). However, the incidence of vomiting was equivalent across both groups (OR 0.64; 95% CI (0.39, 1.04); p = 0.07). This study found that NOAs are good adjuvants in pain management in patients undergoing major abdominal surgery. They aid in reducing the dosage of opioids required for adequate analgesia and thus also reduce the incidence of some of the related adverse events.