Thrombocytopenia during intravenous valproic acid therapy in the neurological intensive care unit

Thrombocytopenia is a common laboratory abnormality among critically ill patients under neurological intensive care unit (NCU) care. Valproic acid (VPA), a widely used antiepileptic drug, is one of the common causes of drug-induced thrombocytopenia. The purpose of this study was to estimate the incidence and risk factors of thrombocytopenia after intravenous VPA therapy among the patients admitted to NCU.

We retrospectively reviewed the medical records of patients who were treated with intravenous VPA during their NCU stay between January 2014 and December 2018. We studied the frequency of thrombocytopenia and further evaluated the risk of thrombocytopenia in these patients.

Among the 283 patients (181 male [64.0%], mean age: [61.0 ± 14.9] years) who were treated with intravenous VPA, thrombocytopenia was observed in 104 patients (36.7%). Thrombocytopenia was associated with several risk factors, including lower baseline platelet counts (<200 × 10⁹ /L); aetiologies other than intracranial or subarachnoid haemorrhage; longer use of VPA (more than 3 days); higher daily dose of VPA (more than 1000 mg/d); concurrent use of VPA with other antiepileptic drugs; infection; and the use of mechanical ventilation. Multivariate analysis found several independent risk factors of thrombocytopenia with intravenous VPA therapy, including lower baseline platelet counts, aetiologies other than intracranial or subarachnoid haemorrhage, use of VPA for more than 3 days and infection.

Thrombocytopenia is common in NCU patients. Because several clinical and laboratory factors are associated with thrombocytopenia, careful use of VPA should be considered in patients with these risk factors.