Intravenous Methocarbamol for Acute Pain After Spine Surgery

Active, not recruiting

• Conditions: Acute Post Operative Pain; Postsurgical Pain Management; Spine Surgery; Acute Pain, Postoperative; Multimodal Analgesia
• Interventions: Drug: Intravenous Methocarbamol

• Registration Number: NCT06659965
• Lead Sponsor: The University of Texas Health Science Center, Houston

Brief Summary

The goal of this target trial emulation is to evaluate the impact of intravenous (IV) methocarbamol on postoperative pain and opioid use in adults undergoing elective spine surgery. The main questions it aims to answer are:

* Does IV methocarbamol reduce pain in the 6 hours following surgery?

* Does IV methocarbamol decrease the need for opioid pain medications in the same period?

Participants who receive IV methocarbamol as part of their routine postoperative care will have their pain scores and opioid consumption tracked for 6 hours after treatment. Pain levels will be measured using standard assessments, and opioid use will be quantified in oral morphine equivalents.

Detailed Description

The IMAPSS study is a target trial emulation evaluating the effect of intravenous (IV) methocarbamol on postoperative pain management and opioid consumption in adult patients undergoing elective spine surgery. The study employs a target trial emulation design to simulate the conditions of a randomized controlled trial using observational data extracted from electronic medical records. The main focus is to determine if administering IV methocarbamol within two hours after surgery reduces postoperative pain scores and opioid use.

Patients will be tracked from the point of their first recorded pain score in the Post-Anesthesia Care Unit (PACU) after surgery to assess for treatment assignment eligibility. Data will be collected at 15-minute intervals, which corresponds to the standard assessment frequency in Phase I PACU care, for up to 12 hours postoperatively for each patient. The primary analysis will use time-varying propensity score matching (TV-PSM) to control for baseline and time-varying confounders. Pain levels will be measured using a time-weighted average (TWA) of pain scores, and opioid consumption will be quantified in oral morphine equivalents (OME).

The primary analysis will utilize TV-PSM, with propensity scores estimated through a Cox proportional hazards model. Matching will create balanced treatment groups at each 15-minute interval. Generalized estimating equations (GEE) will then estimate the effect of IV methocarbamol on the primary outcome (TWA pain) and secondary outcome (cumulative OME) over a 6-hour postoperative period. As a sensitivity analysis, a marginal structural model (MSM) using inverse probability weighting (IPW) will assess the robustness of the findings to the time-varying confounder adjustment.

This study's findings will aim to inform evidence-based recommendations for postoperative pain management and opioid-sparing strategies, potentially providing safer alternatives to conventional opioid-based regimens.

Study Timeline

• Study Start: 2020-01-01
• Primary Completion: 2023-12-31
• Study First Submitted: 2024-10-24
• Study First Submitted QC: 2024-10-24
• Study First Posted: 2024-10-26
• Status Verified: 2025-03
• Last Update Submitted: 2025-03-24
• Last Update Posted: 2025-03-28
• Study Completion: 2025-12-31

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 6000

Inclusion Criteria

• 18 years of age or older
• Undergoing one of the following three elective spine surgeries: (i) Anterior Cervical Discectomy and Fusion (ACDF), (ii) Posterior Spinal Fusion, or (iii) Laminectomy, Laminotomy, or Discectomy

Exclusion Criteria

• Emergency Surgery
• Pregnancy
• Sensitivity to methocarbamol (allergy)
• End-stage renal disease (ESRD)
• Myasthenia gravis

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
IV methocarbamol	Intravenous Methocarbamol	Patients who received intravenous methocarbamol

Primary Outcome Measures

Name	Time	Method
Time-Weighted Average Pain Score	6 hours after treatment assignment	The primary outcome of this study is the Time-Weighted Average (TWA) pain score measured over the 6-hour period following treatment assignment. Pain scores are collected using a standardized numerical pain rating scale, ranging from 0 (no pain) to 10 (worst possible pain). These scores are assessed in 15-minute intervals, the standard frequency for Phase I PACU assessments, throughout the 6-hour follow-up period. The TWA pain score is calculated by averaging these pain ratings, giving greater weight to scores recorded more frequently or for longer periods. This method provides a comprehensive summary of the patient's pain experience over the observed time frame, accounting for fluctuations in pain intensity during recovery. A lower TWA score indicates better pain control and a potentially greater effect of the intervention.

Secondary Outcome Measures

Name	Time	Method
Cumulative Opioid Use	6 hours after treatment assignment	The secondary outcome of this study is the cumulative opioid use measured in Oral Morphine Equivalents (OME) over the 6-hour period following treatment assignment. Opioid doses administered during this timeframe are converted into OME to standardize and compare the total amount of opioids used, accounting for the specific medication, dose, and route of administration. Data on opioid administration are assessed in 15-minute intervals, aligned with standard PACU assessment practices. The cumulative OME reflects the total opioid exposure a patient received, providing a quantitative measure of opioid consumption and its potential reduction with the intervention. Lower cumulative OME values suggest more effective pain management with fewer opioids, indicating the potential benefits of non-opioid alternatives.

Trial Locations

Locations (1)

Memorial Hermann Health System; 🇺🇸 Houston, Texas, United States