Baseline and average platelet count can predict the outcome of patients with aneurysmal subarachnoid hemorrhage

Baseline values and the change of platelet count (PLT) during disease were reported to be associated with prognosis of patients with cancer and intensive care treatment. We aimed to evaluate the association between PLT with the course and prognosis of aneurysmal subarachnoid hemorrhage (SAH).

Admission (AdmPLT) and the 14-days mean PLT (MeanPLT) values of 763 SAH patients treated between 01/2005 and 06/2016 were recorded and, for further analysis, divided into four categories: <150, 150-260, 261-400 and > 400 × 10⁹/L. Primary endpoints were cerebral infarcts in follow-up computed tomography scans, in-hospital mortality and unfavorable outcome at 6-months follow-up defined as modified Rankin scale>3. Adverse events during SAH were assessed as secondary endpoints.

Higher PLT values were independently associated with lower risk of cerebral infarction (MeanPLT: aOR = 0.65 per-PLT-category-increase, p = 0.001), in-hospital mortality (AdmPLT: aOR = 0.64, p = 0.017; MeanPLT: aOR = 0.23, p < 0.0001) and unfavorable outcome (AdmPLT: aOR = 0.70, p = 0.031; MeanPLT: aOR = 0.35, p < 0.0001). Moreover, individuals with poorer outcome were less prone to PLT increase during SAH (mean values: -+20.3 vs + 30.5 × 10⁹/L for cerebral infarction; +9.3 vs + 32.8 × 10⁹/L for in-hospital mortality; +14.4 vs + 31.1 × 10⁹/L for unfavorable outcome). The following adverse events during SAH were related to AdmPLT and/or MeanPLT: non-aneurysm related secondary rebleeding, intracranial hypertension requiring conservative treatment or decompressive craniectomy, sepsis and acute kidney failure.

Low PLT at admission and their less prominent increase during SAH were strongly linked with poor outcome of SAH. Further analysis is required to clarify the background of this association and potential therapeutic implications.