UPMC Study Reports Patterns of COVID-19 Testing from Large Health Care System

MedicalResearch.com Interview with:
Dr. Amy KennedyDr. Amy Kennedy, M.D., M.S
Clinician-Researcher Fellow, General Internal Medicine
University of Pittsburgh 

MedicalResearch.com: What is the background for this study?

Response: UPMC uses a nucleic acid polymerase chain reaction (PCR) test for SARS-CoV-2 and specimen collection is done with a nasopharyngeal swab by trained clinicians. The health system developed its COVID-19 test in early March 2020 in anticipation of the tremendous need for diagnostic capabilities.

My colleagues and I worked with the Wolff Center at UPMC — the health system’s quality care and improvement center — to review the results of more than 30,000 COVID-19 tests performed on adult patients who received care through one of UPMC’s 40 academic, community and specialty hospitals, or 700 doctors’ offices and outpatient sites in Pennsylvania, New York and Maryland. The tests were performed between March 3 and May 3, 2020. Of those tests, 485 were repeated at least once. 

MedicalResearch.com: What are the main findings?

Response: We found that retesting was uncommon, patients positive for COVID-19 stayed positive for an average of three weeks and repeating tests in patients who were initially negative very rarely led to a positive result.

MedicalResearch.com: What should readers take away from your report?

Response: In the U.S., COVID-19 testing capacity is limited — not everyone who wants a test can get one — so we have to be judicious in how we use it. Often, testing decisions are left to individual clinicians, which leads to questions about when and whom to retest for COVID-19, how often false positives or negatives might occur, and the duration of positivity. So, it is important that we understand the value of retesting and what information it can, and cannot, provide.

Among 74 UPMC patients who initially tested positive and were retested, about half were still positive and half were negative. The median time between an initial positive and a repeat positive was 18 days, whereas the median time from initial positive to a negative test was 23 days, suggesting that PCR tests may remain positive until some point in between, around 21 days. The most common reason for repeat testing on someone who initially tested positive was to determine if infection prevention protocols needed to be continued when the patient was discharged.

Among the 418 patients who initially tested negative and were retested, 96.4% were still negative on retesting. Pre-operative asymptomatic screening was the most common reason negative patients were retested, followed by clinical suspicion that the first test was a false negative. For the 15 patients who went from negative to positive, the median time between tests was eight days.

It is important to note that the data was not collected as part of a formal study and testing was done at each clinician’s discretion, so we are unable to calculate a true false negative rate.

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: Although our analysis cannot provide definitive clinical guidance regarding retesting for COVID-19, it does point to several interesting areas for further research. These include identifying predictors of initial false negatives and providing a better estimate for how long someone who tests positive could transmit the virus to others.

MedicalResearch.com: Is there anything else you would like to add?

Response: Additional authors on this research include Jessica Merlin, M.D., Ph.D., M.B.A., Mary K. Hilmes, M.B.A., Linda Waddell, R.N., M.S.N., Alexandra Bartow, R.N., M.S.N., A.C.N.P.-B.C., M.B.A., Carla Baxter, R.N., B.S.N., and Christiane M. Hadi, M.D., M.P.H., M.Sc., all of Pitt or UPMC.

This research was supported by U.S. Health Resources & Services Administration grant T32HP22240. 


Amy J. Kennedy et al, Re-Testing for SARS-CoV-2: Patterns of Testing from a Large U.S. Healthcare System, Infection Control & Hospital Epidemiology (2020). DOI: 10.1017/ice.2020.413


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Last Modified: Aug 10, 2020 @ 9:38 pm

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