Abstract WMP64: Increased Risk Of Adverse Outcomes With Methocarbamol Versus Cyclobenzaprine Use In Medication Naïve Acute Stroke Patients

Introduction: Methocarbamol and Cyclobenzaprine are often used interchangeably as muscle relaxants for acute stroke patients. There is limited data comparing medication side effect profiles within this hemodynamically vulnerable population. Methods: Electronic medical records from 65 health care organizations (Aug 2002-Jul 2022) were used to identify a cohort of medication naïve acute stroke patients (ICD-10 codes I61-I63) who received Methocarbamol or Cyclobenzaprine. A 1:1 matched propensity score was used to adjust for baseline demographic and comorbidity differences. Outcomes included the 30-day relative risk (RR) and risk difference (RD) for: falls, sedation/fatigue, bradycardia, hypotension, seizure, urinary retention, and death. Sensitivity analysis focused on 30-day risk among patients aged > 65 years. Results: Prior to matching, the final cohort consisted of 34,865 stroke patients who received Methocarbamol (n=20,150) or Cyclobenzaprine (n=14,715). A total of 13,667 pairs were matched, all baseline covariates were well balanced. In the adjusted analyses, Methocarbamol (vs. Cyclobenzaprine) use during the acute stroke period was associated with a 44% increased risk of fall (RR: 1.44; 95% CI: 1.31-1.50) sedation/fatigue (RR: 1.54 95% CI: 1.44-1.65), bradycardia (RR: 1.32; 95% CI: 1.19-1.44), hypotension (RR: 1.29 95% CI: 1.20-1.38), and seizure (RR: 1.32 95%CI: 1.24-1.40). Results were not affected by age as adverse event risks were similar among patients aged >65. Conclusions: Compared to Cyclobenzaprine, Methocarbamol use was associated with increased 30-day risk of a range of adverse outcomes across the age spectrum for acute stroke patients.