COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

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Diagnosis Lee J, Song JU Diagnostic accuracy of the Cepheid Xpert Xpress and the Abbott ID NOW assay for rapid detection of SARS-CoV-2: A systematic review and meta-analysis. J Med Virol. 2021 Jul;93(7):4523-4531. doi: 10.1002/jmv.26994. Epub 2021 May 3.

Rapid and accurate diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is essential to prevent the spread of the virus. We investigated the diagnostic accuracy of the Xpert Xpress and the ID NOW assays for rapid detection of SARS-CoV-2 using a systemic review and meta-analysis approach. A systematic literature search was performed using PubMed, Embase, and the Cochrane COVID-19 Study Register. The sensitivity and specificity of these tests for detecting viruses in patients with suspected SARS-CoV-2 infection were pooled. We used commercial and laboratory-developed reverse transcription-polymerase chain reactions as reference standards. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess the risk of bias. We identified 11 studies involving 1734 subjects for the Xpert Xpress assay and 10 studies involving 1778 subjects for the ID NOW assay. The pooled sensitivity and specificity of the Xpert Xpress assay for detection of SARS-CoV-2 were 0.99 (95% confidence interval [CI], 0.97 to 0.99) and 0.97 (95% CI, 0.95 to 0.98), respectively. The pooled sensitivity and specificity of the ID NOW assay were 0.79 (95% CI, 0.69 to 0.86) and 1.00 (95% CI, 0.98 to 1.00), respectively. The studies included in our analysis seemed to have low methodological quality. The Xpert Xpress assay showed excellent diagnostic accuracy for rapid detection of SARS-CoV-2. However, as the ID NOW assay showed relatively low sensitivity, this test might miss several positive samples.

Discipline / Specialty Area Score
Hospital Doctor/Hospitalists
Internal Medicine
Public Health
Infectious Disease
Emergency Medicine
Comments from MORE raters

Emergency Medicine rater

My concern is that this is not a head to head study. It's impossible to know if subjects in the study were similar.

Infectious Disease rater

There have been numerous evaluations of both tests, this one offers nothing new.

Infectious Disease rater

This is a careful analysis of the available data on the sensitivity and specificity of two of the four available rapid COVID-19 tests. As an ID doc, I find this interesting and useful when considering the meaning of a test result in an individual and when advising on which test might be best to implement in a specific screening scenario or Heath system.