Journal of clinical microbiology 2017 03 15() pii 10.1128/JCM.00119-17
Background: The absence of markers of inflammation in the cerebrospinal fluid (CSF) commonly predict the absence of herpes simplex virus (HSV) central nervous system (CNS) infection. Consequently, multiple authors have proposed and validated criteria to defer HSV PCR tests from CSF in immune competent hosts with normal CSF white cells and protein (≤5 cells/mm(3), ≤50 mg/dL, respectively). Immune competence equates to age ≥2 years without HIV or transplant. Adoption of the criteria may erroneously exclude HSV infected persons from a necessary diagnostic test, or alternatively, reduce the costs associated with HSV tests with minimal to no effect on patient care. Little is known about the cost-effectiveness of this approach.Methods: A decision analysis model was developed to evaluate the adoption of criteria to screen HSV tests in CSF. Estimates of input parameter values combined available literature with a multiyear, multisite review at two of the largest healthcare systems in the United States.Results: Adoption of criteria to screen HSV tests proved cost-effective when less than 1 in 200 patients deferred from testing truly had an HSV CNS infection. Similar to prior studies, none of the deferred cases had HSV encephalitis (n=3120). Adoption of the criteria in the United States would save an estimated $127 million ($95 million to $158 million, +/-25%) annually. The model calculations remained robust to variation in test cost, prevalence of HSV infection, and random variation to study assumptions.Conclusion: The adoption of criteria to screen HSV PCR tests in CSF represents a cost-effective approach.