MicroRNA Biomarkers on Day of Injury Among Patients with Post Concussive Symptoms at 28-Days: A Prospective Cohort Study.

Background: After mild traumatic brain injury (mTBI), some patients experience symptoms that persist for weeks to months. Recovery from mTBI is primarily assessed using selfreported symptom questionnaires. Blood biomarkers, including microRNA species, have shown promise to assist diagnosis of mTBI, however, little is known about how blood microRNA measures might predict symptom recovery.

Objective: The aim of this study was to investigate the variances in plasma microRNAs on the day of injury between individuals with mTBI who report post-concussive symptoms at the 28- day mark and those who do not.

Methods: Patients who presented to an adult, tertiary referral hospital emergency department on the day of the injury and were diagnosed with isolated mTBI (n=35) were followed up for 28 days. Venous blood samples were collected and symptom severity was assessed using the Rivermead Post-Concussion Symptom Questionnaire (RPQ) on the day of injury and at 28 days. Patients who reported ongoing symptoms of total RPQ score ≥10 or at least one symptom severity ≥2, were compared to those with lesser symptom severity or symptom resolution.

Results: There were 9 (25.7%; 95%CI: 12.5-43.3) patients who reported persistent symptoms. Day of injury plasma miR-223-3p levels were significantly higher in individuals with ongoing symptoms compared to those without, however, no such differences were observed for miRs 142- 3p, 423-3p, 32-5p, 144-3p, and let-7f-5p.

Conclusion: Acute plasma miR-223-3p levels appear to detect patients who later have persistent symptoms after mTBI. The results demonstrate the potential utility for such biomarkers to assist in decisions towards early referral for therapy after mTBI.