Factors influencing the diagnostic accuracy of the rapid influenza antigen detection test (RIADT): a cross-sectional study

Abstract

ObjectiveTo evaluate the diagnostic accuracy of the rapid influenza antigen detection test (RIADT) and determine which symptoms are relevant to results.DesignSingle-centre, cross-sectional study.SettingPrimary care centre, Tokyo, Japan.Participants82 consecutive outpatients presenting with upper respiratory symptoms and fever ≥37°C at any time from symptom onset, between December 2010 and April 2011.Main outcome measuresResults of history and physical examination including age, sex, temperature, time of test from symptom onset, vaccination record and current symptoms (sore throat, arthralgia and/or myalgia, headache, chills, cough and/or throat phlegm, nasal discharge) were recorded. The RIADT and a fully automated respiratory virus nucleic acid test (Verigene Respiratory Virus Plus; VRV), the latter being the gold standard, were performed. Patients were divided into four groups: false negative (FN), RIADT− and VRV+; true positive (TP), RIADT+ and VRV+; true negative (TN), RIADT− and VRV−; and false positive, RIADT+ and VRV−. Groups were compared regarding age, sex, temperature, time of test from symptom onset, vaccination record and symptoms.ResultsRIADT sensitivity, specificity, positive predictive value and negative predictive value were 72.9% (95% CI 61.5% to 84.2%), 91.3% (79.7% to 102.8%), 95.6% (89.5% to 101.6%) and 56.8% (40.8% to 72.7%), respectively. Time from symptom onset to test was shorter for the FN group than the TP group (p=0.009). No significant differences were detected for the other factors assessed. Results revealed higher temperatures for FN than TN patients (p=0.043), and more FN than TN patients had chills (p=0.058).ConclusionsThe RIADT sensitivity was low, due to early administration of the test. In the epidemic season, the RIADT should not be used for suspected influenza until 12 h after symptom onset. A positive RIADT firmly supports the influenza diagnosis; a negative result does not confirm its absence. High fever and chills might indicate influenza, but additional tests are sometimes necessary.

Comparative epidemiology of influenza A and B viral infection in a subtropical region: a 7-year surveillance in Okinawa, Japan

“…However, RAT results should be expected to show significant heterogeneity due to differences in patient age, virus type and brand variety, all of which can affect test results. Furthermore, some studies describe lower sensitivity for detection of influenza B infection than that of influenza A infection [12, 36–39]. This decrease in sensitivity may cause even lower rates of detection for influenza B, due to increased false negative results in some populations.…”

“…As a result, patients with mild disease, including upper respiratory tract infection, often visit general hospitals directly. In many cases, attending physicians suspecting an influenza-like illness (ILI) will use a rapid antigen test (RAT), which can detect influenza A and B separately [12]. In Okinawa, four representative general hospitals aggregate and report the weekly results of the RATs.…”

Practical Guidance for Clinical Microbiology Laboratories: Viruses Causing Acute Respiratory Tract Infections

“…Use was often restricted to specific specimen types (e.g., NPS or NS), the sensitivities of these assays in pediatric and adult populations varied but were considered to be poor, and the assays could not be used to rule out infection (201,202). Performance characteristics of these assays were typically determined during normal respiratory virus seasons, with acceptable specificity for RSV and FLU (203,204); however, the performance characteristics are significantly reduced when assays are used out of season (205)(206)(207). Many believe that the clinical utility of employing FLU and RSV POC assays, given the high numbers of both false-positive and false-negative results, is questionable (205)(206)(207), and the future long-term availability of rapid antigen detection kits is in doubt.…”

“…Performance characteristics of these assays were typically determined during normal respiratory virus seasons, with acceptable specificity for RSV and FLU (203,204); however, the performance characteristics are significantly reduced when assays are used out of season (205)(206)(207). Many believe that the clinical utility of employing FLU and RSV POC assays, given the high numbers of both false-positive and false-negative results, is questionable (205)(206)(207), and the future long-term availability of rapid antigen detection kits is in doubt. On 23 February 2017, the U.S. Food and Drug Administration (FDA) reclassified rapid antigen influenza virus test kits from class I to class II medical devices (208).…”

Acupuncture Needles Can Carry Hepatitis C Virus

“…Preference was given for deep muscle insertion, as this had resulted in traces of blood on needles in previous work. 3 Needles used for each patient treatment were submerged immediately in 100 mL of TRIzol reagent (Life Technologies) after removal and then sent to the Genomic Study Laboratory of the State University of São Paulo, Brazil.…”