Non-inferiority of intranasal ketamine compared to intravenous morphine for musculoskeletal pain relief among older adults in an emergency department: a randomised controlled trial

Abstract

Objectives: ketamine has potential advantages over morphine for musculoskeletal pain relief. The aim of this study was to compare the analgesic efficacy and safety of intranasal (IN) ketamine to intravenous (IV) morphine for older adults with musculoskeletal pain in the emergency department (ED). Methods: this was a non-inferiority, double-blind, randomised controlled trial of ED patients aged of 65 and older presenting with acute moderate to severe musculoskeletal pain defined as a score ≥5 on an 11-point numeric rating scale (NRS). Patients were randomly assigned to receive IN ketamine or IV morphine. The primary outcome was comparative reduction of NRS pain scores between ketamine and morphine groups at 30 min post-treatment. Secondary outcomes were incidence of adverse events and requirement for rescue therapy. Results: seventy-four patients were eligible for analysis (37 in the IN ketamine and 37 in the IV morphine group). Mean pain score at 30 min did not differ significantly between IN ketamine and IV morphine groups (6.03 versus 5.81). Similarly, the difference in mean NRS change from baseline between IN ketamine and IV morphine groups [(-2.14, 95% CI: -2.79 to -1.48) and (-0.81, 95% CI: -2.36 to -1.26) = -0.32, 95% CI: -1.17 to -0.52] did not reach the non-inferiority margin of 1.3. Adverse events and incidence of rescue therapy also did not differ between groups. Conclusions: intranasal ketamine can provide a non-inferior analgesic effect compared to intravenous morphine for acute musculoskeletal pain in older adults with mild adverse effects and low incidence of rescue analgesic treatment.