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Standard blood laboratory parameters may have diagnostic potential, if polymerase-chain-reaction (PCR) tests are not available on time. We evaluated standard blood laboratory parameters of 655 COVID-19 patients suspected to be infected with SARS-CoV-2, who underwent PCR testing in one of five hospitals in Vienna, Austria. We compared laboratory parameters, clinical characteristics, and outcomes between positive and negative PCR-tested patients and evaluated the ability of those parameters to distinguish between groups. Of the 590 patients (20–100 years, 276 females and 314 males), 208 were PCR-positive. Positive compared to negative PCR-tested patients had significantly lower levels of leukocytes, neutrophils, basophils, eosinophils, lymphocytes, neutrophil-to-lymphocyte ratio, monocytes, and thrombocytes; while significantly higher levels were detected with erythrocytes, hemoglobin, hematocrit, C-reactive-protein, ferritin, activated-partial-thromboplastin-time, alanine-aminotransferase, aspartate-aminotransferase, lipase, creatine-kinase, and lactate-dehydrogenase. From all blood parameters, eosinophils, ferritin, leukocytes, and erythrocytes showed the highest ability to distinguish between COVID-19 positive and negative patients (area-under-curve, AUC: 72.3–79.4%). The AUC of our model was 0.915 (95% confidence intervals, 0.876–0.955). Leukopenia, eosinopenia, elevated erythrocytes, and hemoglobin were among the strongest markers regarding accuracy, sensitivity, specificity, positive and negative predictive value, positive and negative likelihood ratio, and post-test probabilities. Our findings suggest that especially leukopenia, eosinopenia, and elevated hemoglobin are helpful to distinguish between COVID-19 positive and negative tested patients.

BackgroundCoronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is current pandemic disease. Acute polymerase-chain-reaction is the gold standard test for this disease, is not available everywhere. Standard blood laboratory parameters may have diagnostic potential.MethodsWe evaluated standard blood laboratory parameters of 655 COVID-19 patients suspected to be infected with SARS-CoV-2, who underwent PCR testing in one of five hospitals in Vienna, Austria. Additionally, clinical characteristics and 28-day outcome were obtained from medical records. We compared standard blood laboratory parameters, clinical characteristics, and outcomes between positive and negative PCR-tested patients and evaluated the ability of those parameters to distinguish between groups.ResultsOf the 590 study patients including 276 females and 314 males, aged between 20 and 100 years, 208 were tested positive by means of PCR. Patients with positive compared to negative PCR-tests had significantly lower levels of leukocytes, basophils, eosinophils, monocytes, and thrombocytes; while significantly higher levels were detected with hemoglobin, C-reactive-protein (CRP), neutrophil-to-lymphocyte ratio (NLR), activated-partial-thromboplastin-time (aPTT), creatine-kinase (CK), lactate-dehydrogenase (LDH), alanine-aminotransferase (ALT), aspartate-aminotransferase (AST), and lipase. Our multivariate model correctly classified 83.9% of cases with a sensitivity of 78.4%, specificity of 87.3%, positive predictive value of 79.5%, and negative predictive value of 86.6%. Decreasing leucocytes and eosinophils and increasing hemoglobin and CRP were significantly associated with an increased likelihood of being COVID-19 positive tested.ConclusionsOur findings suggest that especially leucocytes, eosinophils, hemoglobin, and CRP are helpful to distinguish between COVID-19 positive and negative tested patients and that a certain blood pattern is able to predict PCR-results.SummaryDecreasing leucocytes and eosinophils and increasing hemoglobin and CRP were significantly associated with an increased likelihood of being COVID-19 positive tested. Each single parameter showed either a high sensitivity (leucocytes, eosinophils, CRP, monocytes, thrombocytes) or specificity (NLR, CK, ALT, lipase), or a sensitivity and specificity around 60% (Hb, LDH, AST).