The Effectiveness of Ketamine Versus Opioids in Patients With Acute Pain in the Emergency Department: A Systematic Review and Meta-Analysis

Opioids are the mainstay of treatment for acute pain in the emergency department. However, its misuse led to the investigation of alternative effective analgesic options for acute pain complaints such as ketamine. Therefore, this systematic review and meta-analysis aimed to determine the effectiveness of ketamine in comparison to opioids in the management of acute pain. This was a systematic review and meta-analysis of randomized controlled trials comparing ketamine to opioids for the relief of acute pain in the ED. Eligible studies were identified by searching the following electronic databases: Medline, Embase, and Central. Studies utilizing either the visual analog scale (VAS) or the numeric rating scale (NRS) for pain scoring in ketamine vs opioids were included. The revised Cochrane risk-of-bias tool for randomized trials was utilized. A random-effects model was performed, and all outcomes were pooled by the inverse variance weighting method. The total number of studies that met the criteria of systematic reviews was nine of which seven of them were included in the meta-analysis with 789 participants. The overall effect of NRS trials was the standardized mean difference (SMD) = -0.07, 95% confidence interval (CI) -0.31 to 0.17, P-value = 0.56, I(2) =85%. While VAS trials showed an overall effect of SMD = -0.02, 95% CI -0.22 to 0.18, P = 0.84, I(2 )= 59%). Moreover, higher adverse events were reported in opioids; however, this was not statistically significant (SMD = 1.23, 95% CI 0.93-1.64, P = 0.15, I2 =38%). Ketamine for immediate pain relief at 15 minutes could be an effective alternative to opioids, but its overall effect in comparison to opioids for improving the pain has not shown a statistically significant difference. There was high heterogeneity in the included studies; thus, a sub-group analysis was performed.