Impact of Vitamin C on the Reduction of Opioid Consumption After an Emergency Department Visit for Acute Musculoskeletal Pain: A Double-Blind Randomized Control Trial Protocol

Study Rationale Literature suggests that the administration of vitamin C has an effect in reducing pain and opioid consumption in the context of immediate postoperative acute pain. However, the investigators could not find evidence on the effectiveness of vitamin C administration after an ED visit in the context of acute pain, notably in trauma injuries like fractures, bruises, sprains, strains, etc. Previous studies have only evaluated pain relief and opioid use for the immediate postoperative period of 24 to 72 hours. Therefore, the investigators propose to evaluate the efficacy of a 14-day regiment of vitamin C given to ED patients discharged with an opioid prescription for acute musculoskeletal (MSK) pain on total opioid consumption after two weeks. The two-week period was chosen because it defines the usual acute pain time frame, during which need for analgesics including opioids is essentially resolved in most patients (88% of our previous study cohort). Furthermore, since vitamin C is also associated with less post-herpetic neuralgia and complex regional pain syndromes (CRPS), the investigators also propose to evaluate its impact on the incidence of chronic pain and CRPS at 3 months.

Study Objectives The primary aim is to compare the difference in the total morphine 5 mg equivalent pills consumed after a two-week follow-up between patients receiving vitamin C versus patients receiving a placebo during these two weeks.

The secondary aims are to compare the following between patients receiving vitamin C vs patients receiving a placebo: pain intensity trajectories, average pain relief during the two-week, side effects, total morphine 5 mg equivalent pills consumed after a two-week follow-up for each type of MSK pain (fracture, contusions, cervical pain, lower back pain, MSK pain at other sites), incidence of chronic pain (including CRPS) at 3 months globally and for each type of MSK pain, incidence of CRPS for limb fractures, and for a wrist fracture in particular at 3 months, and prevalence of opioid use at 3 months.

Study Design The investigators will conduct a multi-center, double-blind, randomized, placebo-controlled trial performed in two tertiary trauma care university-affiliated hospitals located in Montreal and in Quebec City (Quebec, Canada) with an annual census of 60,000 and 67,000 visits, respectively.

Participants and recruitment Consecutive patients (from 8 to 20h every day) diagnosed with an acute musculoskeletal pain complaint ongoing for less than two weeks and discharged from the ED with an opioid prescription will be approached by the treating clinician to participate in the study and obtain their verbal consent to be seen by a research assistant. The decision to prescribe opioids will be at the discretion of the treating physician, but included patients will receive a standardized prescription of 20 pills of morphine 5 mg based on our previous work. The research assistant will then verify the patient's inclusion and exclusion criteria, explain the research protocol, and obtain informed written consent. Patients will be assessed via a two-week electronic (or paper) diary and contacted 3 months after ED discharge.