A retrospective review of empiric acyclovir prescribing practices for suspected viral central nervous system infections: A single-centre study

Acyclovir has an important role in the treatment of viral central nervous system (CNS) infection, especially herpes simplex virus (HSV)-1 encephalitis. It is therefore used broadly as empiric therapy for many patients who present to the hospital with symptoms of a possible neurologic infection. We sought to review our practices in acyclovir prescribing, deprescribing, and associated investigations for the clinical syndromes it treats. Through a retrospective chart review, we identified patients prescribed acyclovir for a possible CNS infection upon admission to Vancouver General Hospital between January 1, 2019, and December 31, 2019. Patient demographics, signs, symptoms, and comorbidities were taken from admission consultation notes or discharge summaries; their investigations, including laboratory tests and imaging, were also recorded. The primary purpose was to describe the appropriateness of empiric acyclovir use in suspected meningoencephalitis cases. Among the 108 patients treated with acyclovir, 94 patients had an indication for starting empiric treatment for encephalitis or meningitis. There was suspicion and workup for encephalitis alone in 76 patients. Among discharge diagnoses, the most common was delirium of a different identified source (18 cases), followed by unknown/other (15 cases). There were seven patients whose CSF viral PCR test was positive for HSV or varicella-zoster virus (VZV); three of them had HSV-1 encephalitis. There were two total adverse events recorded attributed to acyclovir; both cases were of mild acute kidney injury. We found that in many patients, acyclovir was not necessary or could have been stopped earlier, avoiding toxicity and drug costs.