Efficacy of Directigen (R) RSV testing in patient management following admission from a paediatric emergency department

We investigated the use of the Directigen(R) Respiratory Syncytial Virus te st performed under 'Stat Laboratory' conditions, in the management of infan ts after admission from the Paediatric Emergency Department (ED). The study group consisted of 242 consecutive paediatric ED patients tested by Direct igen in the Stat laboratory during the winter 1995-1996 respiratory virus s eason. Specimens were submitted to the Virology Laboratory for confirmatory consensus testing utilizing in part, an in-house multiplex immunofluoresce nce assay (IFA) and conventional virus isolation methodologies. The sensiti vity, specificity positive and negative predictive values for Directigen, I FA, and isolation, were 71, 91, 85, 80%; 98, 100, 100, 99%; and 51, 100, 10 0, 72% respectively. Re-testing of 17 discordant original NP aspirates usin g Directigen, suggested that errors were due to technologist interpretation as well as to overt assay failure. The low analytical sensitivity and spec ificity of Directigen precludes its use in the clinical setting described i n this study. Evening or weekend specimen collection, followed by IFA testi ng in a centralized Virology Laboratory at the start of the next working da y, produces reliable test results. Among the small number of pediatric pati ents who might be candidates for antiviral therapy IFA testing should be ma de available on an on-call basis by Virology Laboratory.