Two additional COVID-19-related tests or procedures should be re-evaluated
by physicians before using
The American Society for Clinical Pathology (ASCP) has selected two more targeted, evidence-based recommendations for COVID-19 testing to add to its existing roster, bringing the total number of COVID-19 tests to review to four. The recommendations have been developed by the ASCP Effective Test Utilization Committee in collaboration with the ASCP Commission on Science, Technology and Policy.
“Our understanding of COVID-19 and the appropriate tests is evolving so quickly that we need to make sure the medical community understands what tests are most appropriate for each patient,” said Lee H. Hilborne, MD, MPH, FASCP, DLM(ASCP)CM, a past ASCP President and chair of the ASCP Effective Test Utilization Committee.
As stewards for laboratory medicine, ASCP is mindful of the need to use the best tests available while conserving scarce testing resources.
The two newest recommendations related to COVID-19 tests state:
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When antigen tests are used to evaluate an asymptomatic population, positive results should be confirmed using a RT-PCR method. “Although the specificity of an antigen test may be high, the positive predictive value is low when these are used to test asymptomatic patients. Otherwise stated, when the pretest probability of infection is low, then false positives will represent a higher percentage of all positive results, so confirmation of positive results using RT-PCR is recommended,” the recommendation states.
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Do not order a respiratory viral panel (i.e., SARS-CoV-2 and other pathogens) for COVID-19 screening to evaluate asymptomatic patients following possible exposure or for return to work/school. Instead, order just the appropriate SARS-CoV-2 (COVID-19) PCR or antigen test. The recommendations note that limited respiratory pathogen panels (e.g., SARS-CoV-2, influenza) have recently become available to evaluate symptomatic patients for possible COVID-19 infection. These panels are appropriate for evaluating symptomatic patients when the pathogens in the panel are part of the differential diagnosis. However, when evaluating asymptomatic patients specifically for COVID-19 reasons (e.g., exposure, return to work, pre-flight), only the SARS-CoV-2 antigen or nucleic acid amplification test is medically necessary.
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In recent months, ASCP has also advised against using serology testing to evaluate patients with upper or lower respiratory tract symptoms of acute COVID-19 infections, and to instead use nucleic acid amplification or antigen testing. “When considering which test is optimal for a patient, the healthcare provider should consider the test performance characteristics (i.e., sensitivity and specificity) and the pre-test probability of infection, in conjunction with the risk to the patient and others of obtaining a false negative or false positive test result,” the recommendation states.
The other recommendation for clinicians, when treating symptomatic patients with a negative antigen test, is to confirm with a more sensitive test (i.e., PCR) if clinically indicated. ASCP’s recommendation notes that antigen tests are less sensitive than nucleic acid amplification tests. Hence, if a patient appears to have COVID-19, but the antigen test is negative, then a follow-up COVID PCR test is strongly recommended.
To view the ASCP COVID-19 testing recommendations, click
here.
Pathologists and laboratory professionals have an opportunity to play a leadership role in addressing these challenges, which is why ASCP has recommended these two targeted COVID-19 tests. It is critical that pathologists and laboratory professionals contribute to improving patient care and reducing the high cost of health care in the United States.
For more information, please contact Edna Garcia, MPH, ASCP Director of Scientific Engagement, at edna.garcia@ascp.org.
Resources:
1. Coronavirus Disease 2019 (COVID-19). Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antigen-tests-guidelines.html. Last updated December 16, 2020. Accessed January 14, 2021.
2. References: Novitas Solutions, Inc. Proposed Local Coverage Determination (LCD): Respiratory Pathogen Panel Testing (DL38916). January 14, 2021. Accessed online at: https://www.cms.gov/medicare-coverage-database/new-search/search.aspx March 20, 2021.
