Caroline Chartrand, MD, MSc; Mariska M.G. Leeflang, DVM, PhD; Jessica Minion, MD, MSc; Timothy Brewer, MD, MPH; Madhukar Pai, MD, PhD
Timely diagnosis of influenza can help clinical management.
To examine the accuracy of rapid influenza diagnostic tests (RIDTs) in adults and children with influenza-like illness and evaluate factors associated with higher accuracy.
PubMed and EMBASE through December 2011; BIOSIS and Web of Science through March 2010; and citations of articles, guidelines, reviews, and manufacturers.
Studies that compared RIDTs with a reference standard of either reverse transcriptase polymerase chain reaction (first choice) or viral culture.
Reviewers abstracted study data by using a standardized form and assessed quality by using Quality Assessment of Diagnostic Accuracy Studies criteria.
159 studies evaluated 26 RIDTs, and 35% were conducted during the H1N1 pandemic. Failure to report whether results were assessed in a blinded manner and the basis for patient recruitment were important quality concerns. The pooled sensitivity and specificity were 62.3% (95% CI, 57.9% to 66.6%) and 98.2% (CI, 97.5% to 98.7%), respectively. The positive and negative likelihood ratios were 34.5 (CI, 23.8 to 45.2) and 0.38 (CI, 0.34 to 0.43), respectively. Sensitivity estimates were highly heterogeneous, which was partially explained by lower sensitivity in adults (53.9% [CI, 47.9% to 59.8%]) than in children (66.6% [CI, 61.6% to 71.7%]) and a higher sensitivity for influenza A (64.6% [CI, 59.0% to 70.1%) than for influenza B (52.2% [CI, 45.0% to 59.3%).
Incomplete reporting limited the ability to assess the effect of important factors, such as specimen type and duration of influenza symptoms, on diagnostic accuracy.
Influenza can be ruled in but not ruled out through the use of RIDTs. Sensitivity varies across populations, but it is higher in children than in adults and for influenza A than for influenza B.
Canadian Institutes of Health Research.
Rapid influenza diagnostic tests (RIDTs) are immunochromatographic assays that detect influenza viral antigens.
This systematic review of 159 studies involving 26 RIDTs found that RIDTs have a high specificity and positive likelihood ratio and modest and highly variable sensitivity for detecting influenza.
Studies that assessed the effect of ordering RIDTs on clinical outcomes were not reviewed.
Positive RIDT results rule in but negative results do not rule out influenza. Whether routine use of these tests is warranted is unclear.
Appendix Figure. Summary of evidence search and selection.
ILI = influenza-like illness; RIDT = rapid influenza diagnostic test.
Appendix Table. Study Characteristics
Table 1. Characteristics of the 159 Included Studies
Figure 1. Quality Assessment of Diagnostic Accuracy Studies assessments of the quality of included studies.
Figure 2. Hierarchical summary receiver-operating characteristic curve plot of rapid influenza diagnostic test studies.
Individual studies (n = 159) are shown as open circles whose size is proportionate to the size of the study. Summary point is shown as a closed circle, representing sensitivity estimates pooled by using bivariate random-effects regression model. The hierarchical summary receiver-operating characteristic curve is shown as a dashed line and is truncated outside the area for which data exist.
Table 2. Accuracy Estimates From Subgroup Analyses
Table 3. Studies That Provided Data on Effect of Duration of Symptoms on Test Accuracy
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Jeffrey, Petrozzino, Principal, Mark J. Atkinson
May 18, 2012
RIDT Performance: Health-Economic Implications
The study done by Chartrand et. at. (Ann Intern Med. 2012;156:500- 511) is a well-done and comprehensive metaanalysis of 26 rapid influenza diagnostic tests' (RIDT) performance in adults and children with influenza -like illness (ILI). Fundamentally, the pooled RIDT performance reported by this study (sensitivity 62.3%, 95% CI 57.9% to 66.6%; specificity 98.2%, CI 97.5% to 98.7%) is the same as that previously reported (sensitivity 72%, CI 62-81; specificity 96%, CI 93-97%) for one widely- used commercial RIDT prior to the H1N1 pandemic (1).
It is important to consider these findings in the context of the commonly used alternative of unaided clinical diagnosis for ILI, where the pooled sensitivity is essentially the same as that of the RIDT (65%, CI 55 -74%), but specificity is about 30% lower (67%, CI 57-76%). This consideration has important health-economic implications. For example, the 8-fold higher false positive rate with unaided clinical ILI diagnosis will predictably lead to more non-indicated antiviral therapy (and associated complications and costs), possible promotion of antiviral drug resistance, complications of undiagnosed or untreated bacterial illness, or undetected illnesses other than influenza. In addition to these clinical implications, the estimated average cost to prevent one false positive result by using RIDTs in place of unaided ILI diagnosis would be -$30.02 to -$11.02 (i.e., $11.02 to $30.02 savings), $8.29 to $41.54, and $123.22 to $199.22, respectively during the peri-influenza, influenza, and epidemic influenza seasons (1).
1. Petrozzino JJ, Smith C, Atkinson MJ. Rapid diagnostic testing for seasonal influenza: an evidence-based review and comparison with unaided clinical diagnosis. J Emerg Med. 2010;39:476-490.e1. [PMID: 20227846]
Jeffrey Petrozzino and Mark J. Atkinson were employees or consultants of The Aequitas Group, Inc. between September 2007 and September 2008.
Chartrand C, Leeflang MM, Minion J, Brewer T, Pai M. Accuracy of Rapid Influenza Diagnostic Tests: A Meta-analysis. Ann Intern Med. 2012;156:500-511. doi: 10.7326/0003-4819-156-7-201204030-00403
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Published: Ann Intern Med. 2012;156(7):500-511.
High Value Care, Infectious Disease, Influenza.
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