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BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) is currently finally determined in laboratory settings by real-time reverse-transcription polymerase-chain-reaction (rt-PCR). However, simple testing with immediately available results are crucial to gain control over COVID-19. The aim was to evaluate such a point-of-care antigen rapid test (AG-rt) device in its performance compared to laboratory-based rt-PCR testing in COVID-19 suspected, symptomatic patients.MethodsFor this prospective study, two specimens each of 541 symptomatic female (54.7%) and male (45.3%) patients aged between 18 and 95 years tested at five emergency departments (ED, n=296) and four primary healthcare centres (PHC, n=245), were compared, using AG-rt (positive/negative/invalid) and rt-PCR (positive/negative and cycle threshold, Ct) to diagnose SARS-CoV-2. Diagnostic accuracy, sensitivity, specificity, positive predictive values (PPV), negative predictive value (NPV), and likelihood ratios (LR+/-) of the AG-rt were assessed.ResultsDifferences between ED and PHC were detected regarding gender, age, symptoms, disease prevalence, and diagnostic performance. Overall, 174 (32.2%) were tested positive on AG-rt and 213 (39.4%) on rt-PCR. AG correctly classified 91.7% of all rt-PCR positive cases with a sensitivity of 80.3%, specificity of 99.1%, PPV of 98.3, NPV of 88.6%, LR(+) of 87.8, and LR(-) of 0.20. The highest sensitivities and specificities of AG-rt were detected in PHC (sensitivity: 84.4%, specificity: 100.0%), when using Ct of 30 as cut-off (sensitivity: 92.5%, specificity: 97.8%), and when symptom onset was within the first three days (sensitivity: 82.9%, specificity: 99.6%).ConclusionsThe highest sensitivity was detected with a high viral load. Our findings suggest that AG-rt are comparable to rt-PCR to diagnose SARS-CoV-2 in COVID-19 suspected symptomatic patients presenting both at emergency departments and primary health care centres.SUMMARYThe rapid SARS-Cov-2 antigen test (SARS-CoV-2 Rapid Antigen Test (Roche Diagnostics), was compared in symptomatic patients with PCR testing both in emergency departments and primary health care centres. It showed an overall sensitivity of 80.3% and specificity of 99.1%; these were higher with lower PCR cycle threshold numbers and with a shorter onset of symptoms.

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).