In-Hospital Amantadine Does Not Improve Outcomes After Severe Traumatic Brain Injury: An 11-Year Propensity-Matched Retrospective Analysis.

BACKGROUND: Disruption of dopamine neurotransmission is associated with functional impairment after severe traumatic brain injury (sTBI). This has prompted the study of dopamine agonists, such as amantadine, to assist recovery of consciousness (RoC). Randomized trials have mostly addressed the post-hospital setting, with inconsistent findings. Therefore, we evaluated the efficacy of early amantadine administration on RoC after sTBI.

METHODS: We searched the medical records of all sTBI patients admitted to our hospital between 2010-2021 who survived ten days post-injury. We identified all amantadine receiving patients and compared them to all non-amantadine recipients and a propensity score matched non-amantadine group. Primary outcome measures included discharge GCS, Glasgow Outcome Scale-Extended (GOS-E) score, length of stay (LOS), mortality, recovery of command following (CF), and days to CF.

RESULTS: In our study population, 60 patients received amantadine and 344 did not. Compared to the propensity score-matched non-amantadine group, the amantadine group had no difference in mortality (86.67% vs 88.33%, P=.783), rates of CF (73.33% vs 76.67%, P=.673), or percentage of patients with severe (3-8) discharge GCS scores (11.11% vs 12.28%, P=.434). Additionally, the amantadine group was less likely to have a favorable recovery (discharge GOS-E 5-8) (14.53% vs 16.67%, P<.001), had a longer LOS (40.5 vs 21.0 days, P<.001), and had a longer time to CF (11.5 vs 6.0 days, P.011)> No difference in adverse events existed between groups.

CONCLUSIONS: Our findings do not support the early administration of amantadine for sTBI. Larger inpatient randomized trials are necessary to further investigate amantadine treatment for sTBI.