Efficacy of Vitamin C in Acute Musculoskeletal Pain Management: A Double-Blind Randomized Controlled Pilot Study

This double-blind randomized controlled pilot study evaluated the feasibility of a larger trial investigating vitamin C's analgesic effects in acute musculoskeletal injury patients, confirming recruitment and adherence feasibility while noting high electronic diary retention rates and inconclusive pain reduction results due to wide confidence intervals.

The Gist

Imagine your body is like a busy construction site. When you break a bone, sprain an ankle, or tear a muscle, it's like a sudden storm has damaged the site. The workers (your immune system) rush in to fix the damage, but in the process, they create a lot of "construction dust" and chaos (inflammation and free radicals). This chaos causes the pain you feel.

For years, doctors have known that Vitamin C is like the ultimate "clean-up crew" and "repair crew" combined. It helps clear the dust and rebuild the walls. We've seen it work wonders in post-surgery patients (people who just had a planned construction project), but we didn't know if it could help people who just walked into the Emergency Room (ED) with a sudden, unplanned injury.

This paper is a test drive (a pilot study) to see if we can run a big, serious experiment to test Vitamin C on these emergency patients.

The Experiment: A Taste Test for Pain

The researchers set up a "blind taste test" in a Montreal hospital. Here's how it worked:

1. The Participants: They looked for adults who had just arrived at the ER with fresh injuries (less than 48 hours old) and were in significant pain.
2. The Teams: They split these patients into two secret teams:
   • Team Vitamin C: They got a powerful dose of Vitamin C (900 mg) twice a day for three days.
   • Team Placebo: They got a "sugar pill" (lactose) that looked exactly the same but did nothing.
3. The Mission: Both teams had to fill out a daily diary for six days, reporting their pain levels and what meds they took. The researchers didn't know who got which pill until the very end.

The Results: Did the Test Drive Work?

The main goal wasn't to prove Vitamin C cures pain yet; it was to see if they could successfully run the whole experiment without things falling apart.

• Recruitment (Finding the Drivers): They found 147 potential drivers. About 60 agreed to join. This is like finding enough people to fill a small bus. It worked, but the researchers noticed they missed a lot of people because the doctors were too busy or confused by other studies happening at the same time.
• The "Lost" Passengers: This was the tricky part. About 30% of the people who started the study didn't finish it.
  • The Analogy: Imagine giving people a paper map to fill out and mail back. A few weeks later, the postal workers went on strike! The paper maps got lost in the mail.
  • People who used electronic diaries (like texting the researchers) stayed on the bus much better than those using paper diaries.
• The Pain Relief: Did the Vitamin C group feel better? The numbers were a bit fuzzy. The group taking Vitamin C did report slightly less pain over the three days, but the difference wasn't huge enough to say "Yes, it definitely works" just yet. It's like saying one car drove slightly smoother than the other, but you need a bigger race to be sure.

The Big Takeaway

Think of this study as a dress rehearsal for a big Broadway show.

• The Good News: The show can be put on. They found enough actors, the script (the study design) made sense, and the actors (patients) generally followed the instructions.
• The Fixes Needed:
  1. Don't miss the actors: Doctors need better instructions so they don't accidentally skip people who could join.
  2. Go digital: Stop using paper maps (diaries) that can get lost in the mail. Everyone should use phones or computers.
  3. Keep the actors engaged: Send more text reminders so people don't forget to finish their part.

Conclusion

The researchers are saying: "We have the green light to build a bigger, better version of this study."

They believe that if they fix the logistics (like using electronic diaries and recruiting earlier), a larger study could prove that a simple, cheap vitamin might be a powerful tool to help people in the ER feel less pain and take fewer strong painkillers. It's a promising spark, but they need to build a bigger fire to see if it really lights up the room.

Technical Summary

1. Problem Statement

Acute musculoskeletal (MSK) injuries represent a significant portion of Emergency Department (ED) visits and are associated with moderate-to-severe pain that can persist and lead to chronic conditions. While preclinical studies and meta-analyses suggest Vitamin C (ascorbic acid) has analgesic and opioid-sparing properties in postoperative settings (via antioxidant mechanisms and collagen synthesis support), its efficacy in managing acute traumatic MSK pain in the ED has not been established. Furthermore, there is a lack of data regarding the feasibility of conducting a large-scale randomized controlled trial (RCT) for this specific population and intervention.

2. Methodology

Study Design:

• Type: Double-blind, placebo-controlled, parallel-group pilot RCT.
• Setting: Single tertiary care university-affiliated trauma center in Montreal, Canada (approx. 60,000 annual ED visits).
• Duration: Recruitment occurred from September 18, 2025, to February 4, 2026.

Participants:

• Inclusion Criteria: Adults (≥18 years) with acute MSK injuries (<48 hours duration), pain intensity >3/10 on a Visual Numerical Rating Scale (VNRS), triaged to the ambulatory section, and able to communicate in French or English.
• Exclusion Criteria: Current/recent Vitamin C use, active cancer, chronic pain, allergy to lactose or Vitamin C, use of cyclosporine/warfarin, or pre-existing conditions like oxalate nephropathy.
• Sample Size: Targeted 60 participants (30 per arm) based on pilot study guidelines.

Intervention:

• Randomization: 1:1 ratio, stratified by fracture status (yes/no), using a centralized web-based system.
• Treatment Arm: 900 mg oral Vitamin C twice daily for 3 days post-discharge.
• Control Arm: Placebo (lactose) matching the treatment in appearance.
• Blinding: Independent pharmacist dispensed pre-packed bottles; participants and researchers were blinded.

Data Collection & Outcomes:

• Primary Outcome (Feasibility): Recruitment rate (target: ≥12 participants/month).
• Secondary Outcomes:
  • SPID72: Time-weighted sum of pain intensity differences over 72 hours.
  • Adherence, loss to follow-up rates, and reasons for refusal.
  • Pain intensity recorded twice daily via a 100-point Visual Analog Scale (VASp) in electronic or paper diaries.
• Statistical Analysis: Intention-to-treat (ITT) and per-protocol analyses using ANCOVA adjusted for fracture status and baseline pain. Missing data imputed via k-nearest neighbors.

3. Key Results

Recruitment and Feasibility:

• Screening: 147 patients screened; 63 excluded (42.9%), 24 refused (16.4%).
• Enrollment: 60 participants randomized (32 Group A, 28 Group B).
• Recruitment Rate: 13.0 participants/month (met the feasibility target of 12/month).
• Consent Rate: 71.4% of eligible patients.

Demographics:

• Mean age: 41.8 years; 50% female.
• Baseline pain intensity at triage: 7.2/10.
• Groups were generally comparable, though Group A had a higher proportion of Black participants and opioid use in the ED compared to Group B.

Follow-up and Compliance:

• Completion Rate: 71.7% (43/60) completed follow-up.
• Loss to Follow-up: Significantly higher in the paper diary group (55.6%) compared to the electronic diary group (16.7%). This was attributed partly to a Canada Post strike affecting mail returns.
• Adherence: High compliance (97.6%) among those who completed the study.

Efficacy (Preliminary):

• SPID72 Analysis: No statistically significant difference was found between groups.
  • Intention-to-Treat (ITT): Least-squares mean difference = 348.7 (95% CI: -698.9 to 1396.4).
  • Per-Protocol: Least-squares mean difference = 357.6 (95% CI: -709.67 to 1424.82).
• Note: As a pilot study, it was not powered to detect clinical efficacy; the wide confidence intervals crossing zero indicate uncertainty rather than proof of no effect.

4. Key Contributions

1. Feasibility Validation: Demonstrated that a large-scale RCT on Vitamin C for acute MSK pain in the ED is feasible, achieving the recruitment target of 13 participants/month.
2. Identification of Operational Barriers:
   • Missed Patients: A high rate of missed eligible patients (42.9% of screened) was attributed to clinician confusion due to a concurrent study with overlapping criteria.
   • Retention Issues: Identified a critical flaw in using paper diaries during potential postal disruptions, leading to a >50% loss-to-follow-up rate in that subgroup.
3. Methodological Insights: Provided data on the impact of recruitment timing (discharge vs. earlier in ED stay) and the necessity of clear differentiation between concurrent studies to improve screening efficiency.

5. Significance and Future Directions

• Clinical Implication: While this pilot did not establish efficacy, it confirms that Vitamin C is safe and acceptable to ED patients with acute MSK injuries. It lays the groundwork for a definitive Phase III trial.
• Strategic Recommendations: The authors propose specific optimizations for a future full-scale trial:
  • Recruitment: Station dedicated research assistants to screen patients immediately post-triage to reduce missed opportunities and clinician confusion.
  • Retention: Abandon paper diaries in favor of electronic systems to prevent data loss from postal strikes; implement automated text reminders and follow-up calls.
  • Education: Use visual infographics in waiting rooms to address patient concerns about side effects and increase interest.
• Conclusion: The study successfully validates the protocol for a larger trial but highlights the need for operational refinements to maximize recruitment and retention rates before investigating the true analgesic efficacy of Vitamin C in this population.