1. Compared to traditional rapid influenza diagnostic tests (RIDTs), digital immunoassays (DIAs), and rapid nucleic acid amplification tests (NAATs) had significantly higher sensitivities for influenza A and B in both adults and children, with specificities that were equally high.
2. The clinical impact and economic impact of DIAs and NAATs should be analyzed to help direct decisions about using rapid testing in clinical practice for influenza diagnosis.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Annually, influenza viruses cause up to 30% of people to be infected with acute respiratory illness. Diagnosing influenza based on clinical symptoms is challenging due to the nonspecific and varied signs of the illness. Therefore, diagnostic tests are a valuable aid in diagnosis. Reverse transcriptase polymerase chain reaction (RT-PCR) is the current gold standard for diagnosing influenza, but the turnaround time takes longer than the clinical encounter. Potential advantages of accurate rapid testing (<30 minutes turnaround time) include quicker antiviral therapy administration, fewer hospitalizations, and decreased unneeded use of antibiotics. This systematic review and meta-analysis sought to evaluate the diagnostic accuracy (compared to RT-PCR) of commercialized RIDTs, DIAs, and rapid NAATs in detecting influenza A and B infection in patients suspected to have influenza. Researchers found that compared to traditional RIDTs, DIAs and NAATs had significantly higher sensitivities for influenza A and B in both adults and children, with specificities that were equally high. The authors suggest that RIDTs are apt to be gradually discontinued due to their poor sensitivity. The clinical impact and economic impact of DIAs and NAATs should be analyzed to help direct decisions about using rapid testing in clinical practice for influenza diagnosis.
Considering that in February 2017 the U.S. Food and Drug Administration (FDA) reclassified and introduced performance standard minimums for rapid influenza tests, a strength of the study is that it provides an updated and thorough review of accuracy data on such tests. Study limitations include unclear risk of bias for many studies included in the analysis, clinical variables underreporting resulting in reduced heterogeneity analysis, limited adult-specific data for NAAT studies, and lack of NAAT studies evaluating point-of-care testing.
In-Depth [systematic review and meta-analysis]: Using PubMed, Embase, BIOSIS Previews, Scopus, Web of Science, and the Cochrane Central Register of Controlled Trials from date of inception through May 2017, researchers found 162 studies (130, 19, and 13 pertaining to RIDTs, DIAs, and NAATs, respectively) meeting study criteria. Criteria included English, French, or Spanish language studies comparing rapid tests (<30 minutes) with RT-PCR for diagnosing influenza. Pediatric-specific data was presented by 46 and 24 studies for influenza A and influenza B, respectively. Adult-specific data was presented by 35 and 16 studies for influenza A and influenza B, respectively. Except for influenza A for NAATs, pooled sensitivity data were higher in pediatric cases by 12.1 to 31.8 percentage points. Pooled sensitivity data for detection of influenza A were 54.4% for RIDTs, 80.0% for DIAs, and 91.6% for NAATs. Pooled sensitivity data for influenza B detection were 53.2% for RIDTs, 76.8% for DIAs, and 95.4% for NAATs. Pooled specificity data were evenly high (>98%).
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