As clinical lab supply chain issues continue, there is no routine lab test that can be used as a biomarker for COVID-19 or as alternative for molecular COVID-19 diagnostic tests, new study finds
As clinical laboratories have struggled with COVID-19 testing supply chain issues and the difficulty in accessing and maintaining adequate testing resources, an area of potential interest has been the possibility that routine clinical laboratory tests can indicate the presence of COVID-19. Laboratory based COVID-19 diagnostics currently rely exclusively on SARS-CoV-2 molecular or antigen testing, and finding a routine clinical laboratory test that could at least indicate the probability of COVID-19 would be very helpful to laboratorians.
An international team of researchers has, however, recently concluded that there is no single routine laboratory test that can serve as a biomarker for COVID-19. Their study was published late November 2020 in the Cochrane Database of Systematic Reviews. The purpose of the study was to identify discrete, routine laboratory tests that could be used to diagnose a COVID-19 infection or to rule one out, allowing for the potential use of another test that could assist in the diagnosis of COVID-19.
67 Routine Clinical Laboratory Tests Explored for Connection to COVID-19
Led by Mariska M.G. Leeflang, DVM, PhD, Associate Professor of Clinical Epidemiology at the University of Amsterdam, the research team studied a total of over 70,000 patients in five different countries. The study examined 67 routine laboratory tests in patients who were PCR-positive for SARS-CoV-2 and compared the results of these tests to patients who were PCR-negative.
While researchers hoped to identify routine clinical laboratory tests that could reliably indicate the possibility of a COVID-19 infection, only three of the laboratory tests examined provided both a sensitivity and specificity above 50%, and none of these tests provided either a sensitivity or specificity of 80%. The three tests that were identified as reaching the 50% threshold included interleukin-6 (IL-6), C-reactive protein (CRP), and lymphocyte count.
The researchers concluded that none of the routine clinical laboratory tests studied “performed well enough to be a standalone diagnostic test for COVID‐19 nor to prioritize patients for treatment.”
New Insights into a Predictive Biomarker for COVID-19
“Basically, short of direct detection of the organism, there are no clearly predictive biomarkers [of COVID-19],” Yuka Manabe, MD, Associate Director of Global Health Research and Innovation at the Johns Hopkins University School of Medicine, recently said in a statement about the results of the study.
“Even though it’s disappointing that we can’t rely on any commonly available basic laboratory tests to make the diagnosis of COVID-19, it’s important we know that so that we don’t try doing it as a way to address shortages of the proper testing,” Manabe explained. “If nothing else, a study like this shows us how important it is to have adequate amounts of proper testing available to our hospitals.”
While the results of this new study do not provide any new ways of identifying COVID-19 infections, they do emphasize the importance of clinical laboratories ensuring they have adequate supplies to perform molecular testing. This study also provides valuable information about the role of multiple routine clinical laboratory tests in the diagnosis of COVID-19 and helps clinicians to better understand that COVID-19 diagnoses ultimately depend entirely on molecular diagnostics.
—By Caleb Williams, Editor, COVID-19 STAT
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