Increased plasma UCH-L1 after aneurysmal subarachnoid hemorrhage is associated with unfavorable neurological outcome.

Objective: Aneurysmal subarachnoid hemorrhage (aSAH) is a common cause of long-term disability and death. After primary hemorrhage, secondary brain injury is the main cause of mortality and morbidity. Despite extensive research, reliable prognostic biomarkers are lacking. We measured ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) levels in aSAH patients to evaluate its prognostic potential. This is the first time that plasma UCH-L1 has been studied as a potential prognostic biomarker in patients with aSAH.

Methods: In this prospective population-based study, UCH-L1 levels were measured in aSAH patients (n=47) for up to five days. UCH-L1 was measured at 0, 12 and 24h after the admission to the intensive care unit (ICU) and daily thereafter until the patient was transferred from the ICU. Only patients whose UCH-L1 was measured within 24h from aSAH were included in the study. The patients' neurological outcome was evaluated with the modified Rankin Scale (mRS) at six months after aSAH.

Results: UCH-L1 levels during the first 24h after aSAH were not significantly different between the groups with favorable (mRS 0-2) and unfavorable (mRS 3-6) neurological outcome. In 22 patients, UCH-L1 levels were obtained for up to five days. In this subgroup, UCH-L1 measured at day five showed significant elevation from baseline levels in patients with unfavorable outcome (p=0.026). Elevated UCH-L1 levels at day five were higher in patients with unfavorable outcome than in patients with favorable outcome (p=0.001).

Conclusions: Elevated UCH-L1 levels during the five-day follow-up were associated with unfavorable neurological outcome. Repetitive measurements of UCH-L1 concentrations with an emphasis on change relative to the individual baseline could be the optimal approach for future clinical studies.