Lateral-flow immunoassay as a diagnostic test for influenza type A and B in children

Background The diagnosis of influenza remains difficult to establish because of its similar symptoms to those of respiratory infection caused by other viruses. The "gold standard" for the diagnosis of influenza is viral culture, which takes time to gain the result and is expensive as well. A simple, rapid, and easily used tool for detection of influenza virus type A and B is needed. Objective To assess the accuracy of lateral-flow immunoassay with Quick Vue Influenza A+B (R) in detecting influenza virus of type A and B. Methods This was an observational study designed for diagnostic test. The subjects were children aged 0-14 years old presenting with acute respiratory infection in primary Health Care Jetis, Godean I, Godean II and Prof. Dr. Sardjito Hospital Yogyakarta, from October 2005 to May 2007. Specimens were collected from both the anterior nares and the throat by physicians for lateralflow immunoassay with Quick Vue Influenza A+B (R) and viral culture as gold standard. Lateral-flow immunoassay was done in each study centre, nasal specimen was placed in an extraction reagent tube and sent to NAMRU II laboratory. Results There were 255 children enrolled in this study. Lateralflow immunoassay by Quick Vue Influenza A+B (R) has sensitivity 70% (CI95% 6; 83%), specificity 93% (CI95% 90; 97%), positive predictive value 68% (CI95% 54; 82%), negative predictive value 94% (CI95% 91; 97%), positive likelihood ratio 10,56 (CI95% 6,14; 18,19) and negative likelihood ratio 0,32 (CI95% 0,21; 0,51). Conclusion Lateral-flow immunoassay (Quick Vue Influenza A+B (R)), nasal swab specimen is not accurate to detect influenza virus A and B in children.