Rapid influenza diagnostic tests (RIDTs) that detect influenza viral antigens are often used at the point of care to obtain quick diagnostic test results. While these tests were developed and introduced prior to the emergence of influenza A(H1N1) 2009, clinicians have utilized these tests routinely to identify patients infected with influenza A(H1N1) 2009 and to make treatment decisions for those patients. Although the specificity of RIDTs as compared to real-time RT-PCR has been shown to be high (90–100%), substantial variation in testing sensitivity (17·8–76·7%) in detecting influenza A(H1N1) 2009 has been reported.1–5
Previous studies have shown that RIDT sensitivity was correlated with increasing viral titer2,6,7 and that higher RIDT sensitivity was found in younger age groups than older groups.3,5,8,9 However, these studies were conducted either in pediatric patients or with a small sample of older patients.
The purpose of this study was to evaluate RIDT performance for the detection of influenza A(H1N1) 2009 in patients by age group, and to determine the association of patient age with RIDT performance.