Herpes Simplex Virus PCR testing and acyclovir use in children: a single institution five year review.

Background: Herpes Simplex Virus (HSV) causes significant morbidity and mortality if acyclovir is delayed for invasive infection. The gold standard for diagnosis is skin, blood or cerebral spinal fluid (CSF) PCR for which UMass Memorial Medical Center (UMMC) uses a referral laboratory. Our objectives were 1) To measure the empiric use of acyclovir for suspected HSV infection in the pediatric population at UMMC over 5 years. 2) To determine if having on-site HSV PCR, with predicted turn-around time (TAT) of 36 hours, could decrease acyclovir exposure and length of stay and 3) to document renal toxicity from acyclovir.

Methods: We performed a retrospective chart review of patients ≤21 years with suspected HSV infection (HSV PCR sent and >1 dose of acyclovir administered) over five years. We collected demographics, indication for acyclovir, HSV PCR TAT, number of acyclovir doses received, length of stay, and renal function. We defined acyclovir as empiric if it was discontinued within 24 hours of a negative HSV PCR. We calculated excess acyclovir doses among patients receiving empiric treatment based on a 36-hour TAT verses actual TAT. We calculated potential excess length of stay for patients receiving empiric acyclovir who were discharged within 24 hours of a negative HSV PCR. We measured renal toxicity using the bedside Schwartz calculation for creatinine clearance and the Pediatric RIFLE criteria. The protocol was approved by the Institutional Review Board.

Results: 109 patients met inclusion criteria. Subjects included 61 males (57%) and 46 females (43%), ages ranging from 1 day old to 21 years of age. Preliminary results show a mean TAT of 80.8 hours, ranging from 22 to 148 hours. Among 74 subjects receiving empiric acyclovir, 176 doses of acyclovir and 62 hospital days would have been saved if all TAT had been 36 hours. A total of 12 patients (11%) met pediatric RIFLE criteria during acyclovir use.

Conclusion: Our preliminary conclusions are that a modest number of excess acyclovir doses were given due to prolonged TAT of HSV PCRs. A larger cost saving of in-house HSV PCR testing may lie in earlier discharges after HSV infection has been ruled out. Acyclovir is overall safe, with a minority of patients developing reversible renal toxicity.