title: Performance of influenza rapid antigen testing in influenza in emergency department patients.
abstract: BACKGROUND
  The use of rapid antigen tests to triage specimens for polymerase chain reaction (PCR) testing from emergency department patients with influenza-like illness during surveillance for novel influenza viruses has been suggested.
  
  
  OBJECTIVE
  To measure the observed sensitivity and specificity for a widely used rapid antigen test (Binax) using a PCR-based assay (Medical Diagnostic Laboratories).
  
  
  METHODS
  Nasopharyngeal samples were taken with flocked swabs (Copan Diagnostics) from patients presenting to the emergency department of a community hospital. Samples were analysed using a rapid antigen and a PCR-based test. PCR testing was used as the criterion reference. Sensitivity and specificity were calculated for influenza and influenza A. Positive predictive values were calculated over a range of possible prevalence.
  
  
  RESULTS
  Samples from 566 unique patients were tested using both methods. Sensitivity was 69.1% (95% CI 58.9% to 78.1%) and specificity was 97.7% (95% CI 95.8% to 98.8%) for the detection of any influenza and 75.3% (95% CI 64.7% to 84.0%) and 97.8% (95% CI 95.9% to 98.9%), respectively, for influenza A only. The resultant positive predictive value ranges from 23% to 77% when the prevalence ranges from 1% to 10%.
  
  
  CONCLUSIONS
  When planning early outbreak surveillance, provision of adequate PCR testing capacity rather than triaging specimens using rapid antigen testing for influenza is advisable.
authors.affiliation: Department of Emergency Medicine, Kern Medical Centre, Bakersfield, CA 93305, USA.
authors.forename: C
authors.initials: C
authors.lastname: Biggs
authors.forename: P
authors.initials: P
authors.lastname: Walsh
authors.forename: C L
authors.initials: CL
authors.lastname: Overmyer
authors.forename: D
authors.initials: D
authors.lastname: Gonzalez
authors.forename: M
authors.initials: M
authors.lastname: Feola
authors.forename: E
authors.initials: E
authors.lastname: Mordechai
authors.forename: M E
authors.initials: ME
authors.lastname: Adelson
authors.forename: K T
authors.initials: KT
authors.lastname: Iacono
mesh_terms: D000956:Antigens, Viral / Q000032:analysis*; D006801:Humans; D007118:Immunoassay; D007251:Influenza, Human / Q000175:diagnosis*; D009305:Nasopharynx / Q000821:virology; D009975:Orthomyxoviridae / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D014421:Turkey
chemical_list: D000956:Antigens, Viral