Evaluation of a novel, rapid antigen detection test for the diagnosis of SARS-CoV-2.

BACKGROUND: Severe 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. METHODS: For 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. RESULTS: Differences 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%). CONCLUSIONS: The 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.

Evaluation of the AMP SARS-CoV-2 rapid antigen test in a hospital setting.

OBJECTIVES: Quick and inexpensive SARS-CoV-2 screening and frontline testing are in growing demand. Our study aimed to evaluate the performance of the immunochromatographic AMP rapid antigen test (AMP RAT) compared to the gold-standard real-time reverse transcription PCR (rRT-PCR) in a hospital cohort. METHODS: A total of 392 patients, who presented consecutively with COVID-19 symptoms in our emergency department, were included in this retrospective study. Two swabs were collected per patient: a nasopharyngeal for the RAT and a combined naso- and oropharyngeal for the rRT-PCR. A positive rRT-PCR (defined as cycle threshold (Ct) < 40) was found in 94 (24%) patients. RESULTS: In our cohort with a median patient age of 70, overall sensitivity and specificity of the AMP RAT was 69.2% (58.8-78.3, 95% CI) and 99.7% (98.1-100.0, 95% CI), respectively. In patients with a Ct value < 25 and < 30, higher sensitivities of 100.0% (89.4-100.0, 95% CI) and 91.8% (81.9-97.3%, 95% CI) were observed. CONCLUSIONS: The AMP RAT showed a high sensitivity in patients with a Ct value < 25 and < 30 and might be helpful for frontline testing whenever rRT-PCR is not readily available.

Standard blood laboratory values as a clinical support tool to distinguish between SARS-CoV-2 positive and negative patients.

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.

Serum level of IP-10 increases predictive value of IL28B polymorphisms for spontaneous clearance of acute HCV infection.

BACKGROUND & AIMS: Single nucleotide polymorphisms (SNPs) in IL28B and serum levels of interferon γ inducible protein 10 (IP-10) predict outcomes of antiviral therapy in patients with chronic hepatitis C. We associated IL28B SNPs rs12979860 and rs8099917, along with serum levels of IP-10, with outcomes of patients with acute hepatitis C (AHC). METHODS: We studied 120 patients with AHC (64 male; 37 ± 16 years old) and 96 healthy individuals (controls). The IL28B SNPs rs12979860 and rs8099917 were detected using real-time polymerase chain reaction; serum concentrations of IP-10 were measured by enzyme-linked immunosorbent assays of 62 patients with AHC. RESULTS: Hepatitis C virus was cleared spontaneously from 59 patients (49.2%). The IL28B rs12979860 C/C genotype was more frequent among patients with AHC than controls (62.5% vs 39.6%; P < .001) and among patients with spontaneous clearance than those without (74.6% vs 51.7%; P = .02) (positive predictive value, 60.3%). Patients with IL28B rs12979860 C/C more frequently developed jaundice (53.2% vs 27.6%; P = .022) than carriers of the T allele. The median level of IP-10 was lower among patients with AHC and spontaneous clearance (764 [113-2470] pg/mL) than those without spontaneous clearance (1481 [141-4412] pg/mL; P = .006). Based on receiver operating characteristic analysis, 540 pg/mL IP-10 was set as the cutoff for patients most likely to have spontaneous clearance (positive predictive value, 71.4%; negative predictive value, 65.9%). Including data on IP-10 levels increased the ability of the IL28B rs12979860 C/C to identify patients most likely to have spontaneous clearance (83% of those who had an IP-10 level <540 pg/mL and 32% who had an IP-10 level >540 pg/mL) (P < .01). CONCLUSIONS: The combination of serum level of IP-10 and SNPs in IL28B can identify patients with AHC who are most likely to undergo spontaneous clearance and those in need of early antiviral therapy.

Platelet count/spleen diameter ratio for the noninvasive diagnosis of esophageal varices: results of a multicenter, prospective, validation study.

BACKGROUND AND AIMS: Noninvasive assessment of esophageal varices (EV) may improve the management of patients with cirrhosis and decrease both the medical and financial burden related to screening. In this multicenter, international study, our aim was to prospectively validate the use of the platelet count/spleen diameter ratio for the noninvasive diagnosis of EV. METHODS: A total of 218 cirrhotic patients underwent screening endoscopy for EV. Platelet count/spleen diameter ratio ((N/mm3)/mm) was assessed in all patients and its diagnostic accuracy was calculated. On the basis of previous results, a platelet count/spleen diameter ratio cutoff of 909 was applied to this population. The diagnostic accuracy of the platelet count/spleen diameter ratio was further evaluated for both severity and etiology of disease subgroups. RESULTS: Prevalence of EV was 54.1%. The platelet count/spleen diameter ratio had 86.0% (95% CI, 80.7-90.4%) diagnostic accuracy for EV, which was significantly greater as compared with either accuracy of platelet count alone (83.6%, 95% CI 78.0-88.3%, P= 0.038) or spleen diameter alone (80.2%, 95% CI 74.3-85.3%, P= 0.018). The 909 cutoff had 91.5% sensitivity (95% CI 85.0-95.9%), 67.0% specificity (95% CI 56.9-76.1%), 76.6% positive predictive value, 87.0% negative predictive value, 2.77 positive likelihood ratio, and 0.13 negative likelihood ratio for the diagnosis of EV. Accuracy of the platelet count/spleen diameter ratio was maintained for both severity and etiology of disease subgroups. CONCLUSIONS: The platelet count/spleen diameter ratio may be proposed as a safe and reproducible means to improve the management of cirrhotic patients who should undergo screening endoscopy for EV.

Rapid suppression of hematopoiesis by standard or pegylated interferon-alpha.

BACKGROUND & AIMS: Treatment of chronic hepatitis C with interferon (IFN)-alpha often has hematotoxic effects. We evaluated the effects of acute vs. chronic and standard vs. pegylated IFN-alpha on hematopoiesis. METHODS: We studied hematopoiesis in 46 patients with chronic hepatitis C receiving single high-dose IN-Falpha2b followed by daily dose standard or weekly pegylated IFN before combination antiviral therapy. RESULTS: Single high-dose therapy resulted in a significant drop in hemoglobin (HB), leukocytes, and platelet count. Although platelets, stimulated by a significant increase in thrombopoietin (TPO), and leukocytes recovered quickly, HB remained below baseline for 7 days. Daily standard or weekly pegylated IFN-alpha leads to a more pronounced drop in all 3 lineages with concomitant increases in TPO and erythropoietin (EPO). No difference was observed between standard and pegylated IFN, except for HB, which fell more during pegylated IFN therapy. Consecutive combination antiviral therapy aggravated the anemia but not the drop in leukocytes or thrombocytes. CONCLUSIONS: The drop in all 3 hematopoietic lineages through IFN-alpha treatment, high-dose standard, standard daily dose, or pegylated, is caused by a combination of bone marrow inhibition and probably some other rapid acting mechanisms. Hematopoietic growth factors are increased as a consequence but cannot overcome the bone marrow suppression.