A Randomized Control Trial Comparing the Safety and Analgesic Efficacy of Diclofenac Administered Through Intramuscular versus Oral Route in Patients with Acute Musculoskeletal Injuries

Background: Clinical trials comparing efficacy of NSAIDs administration through different routes have provided indefinite conclusions due to sev-eral limitations. The current study aimed to ascertain early post-medication pain reduction in participants presenting with acute musculoskeletal injuries (MSI) to the emergency department (ED) receiving intramuscular (IM) versus per oral (PO) diclofenac. Methods: This was a prospective, double blinded, randomized control trial. Adults (18-65 years of age) presenting to the ED within 24 hours of acute MSI, and who had a triage pain score on Numerical rating scale (NRS) of at least 5 were enrolled in this study. Participants were assigned (1:1) to either intramuscular (75mg) or oral (100mg) diclofenac group using a computer generated randomized concealed list in the blocks of six and eight. The primary objective was to evaluate and compare the proportions of IM vs. PO participants attaining a 50% reduction in pain score at 30 minutes from t0. Findings: Between January 15, and June 10, 2018, we enrolled 300 participants (150 in the IM diclofenac group, and 150 in the PO diclofenac group) in the study. The primary outcome was achieved in 99.3( 95% CI 96.3-100) in the intramuscular group and 86.7( 95% CI 80.2- 91.7) in per oral group. This corresponds to a number needed to teat (NNT) of 8 cases (95% CI, 6-14) receiving IM rather than the PO diclofenac, in order to achieve one additional case of 50% pain reduction within a half-hour of drug administration. There were no adverse events experienced in any treatment group. Interpretation: The overall efficacy and time taken for pain reduction by IM diclofenac injection has relatively little advantage over per oral admin-istration of diclofenac. Considering the additional resources and risks entailed in IM administration, per oral administration is prefera-ble when and if clinical circumstances allow a choice in NSAID administration route. Trial Registry: The trial was registered with ClinicalTrials.gov, number NCT03472339. Funding: Hamad Medical Corporation, Medical Research Center, Doha, Qatar (MRC#16413/16) Declaration of Conflict of interest: There is no conflict of interest among the authors. Ethics Approval Statement: The HGH institutional ethics board approved the study.