Diagnostic Accuracy of Routine Laboratory Tests for COVID-19

Objectives: COVID-19 has ravaged healthcare systems across the globe. Availability of and timely results for PCR testing have made diagnosis in the Emergency Department challenging. Therefore, we sought to determine if routine serum laboratory tests could be diagnostic of COVID-19. Methods: All patients tested for COVID-19 at an academic hospital in Pennsylvania between 1 March 2020-28 April 2020, were retrospectively analyzed. Results of COVID-19 PCR testing and laboratory tests were recorded. Mean difference was used to determine which tests demonstrated a significant difference, with p < 0.01 used, due to multiple observations. The tests that met these criteria had ROC curves and sensitivity and specificity determined. Results: Of the patients identified, 553 had had any laboratory test. All tests that showed a statistically significant mean difference were lower in COVID-19 positive patients. These included white blood cell count, platelets, absolute neutrophil count, absolute lymphocyte count, absolute eosinophil count, alkaline phosphatase, albumin, troponin T, lactic acid, D-DIMER, and procalcitonin. D-Dimer was excluded for only having four tests completed in COVID-19 positive patients. The remaining tests had a specificity of 88-96%, with a sensitivity of 5-50%. Discussion: No single serum laboratory test demonstrated sensitivity for COVID-19. Some tests might be moderately specific, but this was of limited clinical use. Future research should focus on a combination of tests to diagnose COVID-19, and healthcare systems should work to obtain rapid and accurate PCR tests to diagnose COVID-19.