The following is a summary of “Low-dose ketamine versus morphine in the treatment of acute pain in the emergency department: A meta-analysis of 15 randomized controlled trials,” published in the February 2024 issue of Emergency Medicine by Guo, et al.

For a study, researchers sought to conduct a meta-analysis to compare the efficacy and safety of ketamine and morphine in adult patients presenting with acute pain in the emergency department (ED).

Following the Cochrane methodology, the meta-analysis focused on randomized controlled trials (RCTs) comparing low-dose ketamine with morphine in adult ED patients with acute pain. Only RCTs with an experimental group receiving low-dose ketamine and a control group receiving morphine were eligible. The primary outcome measured included the numeric rating scale (NRS) and visual analog scale (VAS). Secondary measures encompassed complete pain resolution, NRS reduction ≥3 points, NRS reduction ≥50% or 60%, change of NRS score, VAS score, rescue analgesia, satisfaction, and adverse events. Subgroup analysis was conducted for studies utilizing intravenous and intranasal ketamine administration. The Review Manager Database was used for data analysis.

About 15 RCTs involving 1,768 patients were included. The ketamine group exhibited lower NRS scores compared to the morphine group at 30 minutes post-treatment (MD, −0.77 [95% CI, −0.93 to −0.61]; P < 0.00001), while morphine demonstrated superior analgesic effects at 120 minutes (MD, 0.33 [95% CI, 0.15 to 051]; P = 0.0003). Complete pain resolution was more frequent in the ketamine group at 15 minutes (RR 3.18, 95% CI 1.75 to 5.78; P = 0.0001). Additionally, ketamine showed a lower incidence of adverse events requiring intervention compared to morphine (RR, 0.34 [95% CI, 0.18 to 0.66]; P = 0.001). Subgroup analysis revealed that intravenous ketamine was more effective than morphine at reducing VAS scores at 30 minutes. However, intranasal ketamine was less effective on the 30-minute VAS score compared to morphine.

Ketamine provided better analgesic effects in the early stages post-treatment, whereas morphine maintained longer-lasting effects. Furthermore, ketamine demonstrated a lower incidence of adverse events requiring intervention compared to morphine. Subgroup analysis indicated that intravenous ketamine was more effective than intranasal administration.

Reference: sciencedirect.com/science/article/abs/pii/S073567572300668X