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Padoan A, Talli I, Cosma C, Moz S, Furlan G, Navaglia F, Marchioro L, Zaninotto M, Basso D, Plebani M. Analytical and clinical evaluations of SNIBE Maglumi chemiluminescent immunoassay for the detection of SARS-CoV-2 antigen in salivary samples. Clin Chem Lab Med 2024; 62:572-577. [PMID: 37787733 DOI: 10.1515/cclm-2023-0947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 09/21/2023] [Indexed: 10/04/2023]
Abstract
OBJECTIVES In this study, we describe the analytical and clinical performances of the SNIBE Maglumi SARS-CoV-2 antigen fully-automated chemiluminescent immunoassay (MAG-CLIA) on salivary samples. METHODS Limit of detection (LOD), linearity and precision were tested for values close to or below the declared LOD. Clinical performance of MAG-CLIA was evaluated on leftover salivary samples from the healthcare workers (HCW) surveillance program, at the University-Hospital of Padova. Salivary samples were analyzed by Lumipulse G SARS-CoV-2 Ag, and in case where the values exceeded 0.41 ng/L, further testing was conducted using TaqPathTM COVID-19 RT-PCR (Applied Biosystems, Thermo Fisher Scientific). RESULTS The estimated MAG-CLIA LOD was 3 ng/L, with repeatability of 7.5 %. Good linearity was demonstrated by diluting two samples at 52.7 ng/L and 211.4 ng/L. Of the 228 HCW samples, 59/228 (25.9 %) were positive, 169/228 (74.1 %) were negative. MAG-CLIA SARS-CoV-2 sAg median level (and interquartile range [IQR]) was 5.03 ng/L (<0.001-35.8 ng/L) for positive and <0.001 ng/L (<0.001 ng/L) for negative samples. MAG-CLIA AUC was 0.795 (95 % CI: 0.720-0.871). Using the best cut-off, 3.5 ng/L, sensitivity and specificity were 57.1 % (95 % CI: 42.2-71.2 %) and 97.0 % (95 % CI: 93.2-99.0 %), respectively. The agreement with the molecular assay was 88.1 % (Cohen's kappa 0.606 [SE=0.066, p<0.001]). CONCLUSIONS The analytical performances of MAG-CLIA are satisfactory, also when values below LOD were tested. In saliva samples, although specificity was elevated, clinical performance was not comparable with that on nasopharyngeal swabs (NPS).
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Affiliation(s)
- Andrea Padoan
- Department of Medicine (DIMED), University of Padova, Padova, Italy
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
- QI.LAB.MED., Spin-off of the University of Padova, Padova, Italy
| | - Ilaria Talli
- Department of Medicine (DIMED), University of Padova, Padova, Italy
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
| | - Chiara Cosma
- Department of Medicine (DIMED), University of Padova, Padova, Italy
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
- QI.LAB.MED., Spin-off of the University of Padova, Padova, Italy
| | - Stefania Moz
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
| | - Giulia Furlan
- QI.LAB.MED., Spin-off of the University of Padova, Padova, Italy
| | - Filippo Navaglia
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
| | - Lucio Marchioro
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
- QI.LAB.MED., Spin-off of the University of Padova, Padova, Italy
| | - Martina Zaninotto
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
- QI.LAB.MED., Spin-off of the University of Padova, Padova, Italy
| | - Daniela Basso
- Department of Medicine (DIMED), University of Padova, Padova, Italy
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
- QI.LAB.MED., Spin-off of the University of Padova, Padova, Italy
| | - Mario Plebani
- Department of Medicine (DIMED), University of Padova, Padova, Italy
- Laboratory Medicine Unit, University-Hospital of Padova, Padova, Italy
- QI.LAB.MED., Spin-off of the University of Padova, Padova, Italy
- Clinical Biochemistry and Clinical Molecular Biology, School of Medicine, University of Padova, Padova, Italy
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Bernasconi L, Neyer P, Oberle M, Schmid B, Martin E, Fankhauser H, Haubitz S, Hammerer-Lercher A. Efficiency evaluation of a SARS-CoV-2 diagnostic strategy combining high throughput quantitative antigen immunoassay and real time PCR. Clin Chem Lab Med 2023; 61:1661-1669. [PMID: 36947812 DOI: 10.1515/cclm-2023-0087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 03/08/2023] [Indexed: 03/24/2023]
Abstract
OBJECTIVES Laboratory testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has played an important role in the effort to prevent and contain local outbreaks. The aim of this study was to assess the diagnostic accuracy of a new fully automated SARS-CoV-2 laboratory-based antigen assay (CoV2Ag) and to explore the efficiency of a diagnostic algorithm combining antigen and conventional high-throughput molecular assays to address potential future challenges of the SARS-CoV-2 pandemic. METHODS One thousand two hundred and twenty four consecutive nasopharyngeal swabs were tested using RT-PCR and CoV2Ag assay. RESULTS The overall sensitivity and specificity of CoV2Ag were 79.1 and 97.8%, respectively. When the analysis was restricted to cases with Ct values ≤30, the sensitivity of the assay improved to 98.1%. Acceptable sensitivity was found when the analysis was limited to patients presenting within one or two to four days of symptom onset (80.5 and 84.8%, respectively). A retrospective analysis of the use of a two-step diagnostic approach combining the CoV2Ag assay and RT-PCR during an acute pandemic phase of 97 days showed a potential reduction in the number of RT-PCR tests by 36.1%, corresponding to savings in reagent costs and technician workload of approximately €8,000 and 10.5 h per day, respectively. CONCLUSIONS Our data show that the proposed algorithm represents a valid alternative diagnostic approach to increase testing efficiency during future pandemic phases with high positivity rates (>20%) and elevated numbers of RT-PCR test requests.
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Affiliation(s)
- Luca Bernasconi
- Institute of Laboratory Medicine, Kantonsspital Aarau AG, Aarau, Switzerland
| | - Peter Neyer
- Institute of Laboratory Medicine, Kantonsspital Aarau AG, Aarau, Switzerland
| | - Michael Oberle
- Institute of Laboratory Medicine, Kantonsspital Aarau AG, Aarau, Switzerland
| | - Bettina Schmid
- Institute of Laboratory Medicine, Kantonsspital Aarau AG, Aarau, Switzerland
| | - Eileen Martin
- Department of Infectious Diseases and Hospital Hygiene, Kantonsspital Aarau AG, Aarau, Switzerland
| | - Hans Fankhauser
- Institute of Laboratory Medicine, Kantonsspital Aarau AG, Aarau, Switzerland
| | - Sebastian Haubitz
- Department of Infectious Diseases and Hospital Hygiene, Kantonsspital Aarau AG, Aarau, Switzerland
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Lippi G, Henry BM, Plebani M. Pooled analysis of laboratory-based SARS-CoV-2 antigen immunoassays. Clin Chem Lab Med 2023; 61:e165-e167. [PMID: 36634259 DOI: 10.1515/cclm-2022-1321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 01/03/2023] [Indexed: 01/13/2023]
Affiliation(s)
- Giuseppe Lippi
- IFCC Task Force on COVID-19, Milano, Italy
- IFCC WG on SARS-CoV-2 Variants, Milano, Italy
- Section of Clinical Biochemistry and School of Medicine and School of Medicine, University of Verona, Verona, Italy
| | - Brandon M Henry
- IFCC Task Force on COVID-19, Milano, Italy
- IFCC WG on SARS-CoV-2 Variants, Milano, Italy
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA
| | - Mario Plebani
- IFCC Task Force on COVID-19, Milano, Italy
- IFCC WG on SARS-CoV-2 Variants, Milano, Italy
- Department of Medicine, University of Padova, Padova, Italy
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Pighi L, Henry BM, Mattiuzzi C, De Nitto S, Salvagno GL, Lippi G. Cost-effectiveness analysis of different COVID-19 screening strategies based on rapid or laboratory-based SARS-CoV-2 antigen testing. Clin Chem Lab Med 2023; 61:e168-e171. [PMID: 36848496 DOI: 10.1515/cclm-2023-0164] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 02/18/2023] [Indexed: 03/01/2023]
Affiliation(s)
- Laura Pighi
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda (VR), Italy; and Service of Clinical Governance and Medical Direction, Provincial Agency for Social and Sanitary Services (APSS), Trento, Italy
| | - Brandon M Henry
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Camilla Mattiuzzi
- Service of Clinical Governance and Medical Direction, Provincial Agency for Social and Sanitary Services (APSS), Trento, Italy
| | - Simone De Nitto
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda (VR), Italy; and Service of Clinical Governance and Medical Direction, Provincial Agency for Social and Sanitary Services (APSS), Trento, Italy
| | - Gian Luca Salvagno
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda (VR), Italy; and Service of Clinical Governance and Medical Direction, Provincial Agency for Social and Sanitary Services (APSS), Trento, Italy
| | - Giuseppe Lippi
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Clinical Governance and Medical Direction, Provincial Agency for Social and Sanitary Services (APSS), Trento, Italy
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Pighi L, Henry BM, De Nitto S, Salvagno GL, Lippi G. Reliability of a single-nostril nasopharyngeal swab for diagnosing SARS-CoV-2 infection. Diagnosis (Berl) 2023; 10:326-327. [PMID: 36797826 DOI: 10.1515/dx-2023-0014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Accepted: 02/06/2023] [Indexed: 02/18/2023]
Affiliation(s)
- Laura Pighi
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Brandon M Henry
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Simone De Nitto
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Gian Luca Salvagno
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Giuseppe Lippi
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
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Pighi L, Henry BM, De Nitto S, Gianfilippi G, Salvagno GL, Plebani M, Lippi G. Clinical assessment of SNIBE Maglumi SARS-CoV-2 antigen fully-automated chemiluminescent immunoassay. Clin Chem Lab Med 2023; 61:1506-1510. [PMID: 36883744 DOI: 10.1515/cclm-2023-0181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 02/27/2023] [Indexed: 03/09/2023]
Abstract
OBJECTIVES Given that SARS-CoV-2 antigen tests will represent a pillar for supporting or surrogating molecular testing in the endemic period, we report here the clinical performance of the new SNIBE Maglumi SARS-CoV-2 antigen fully-automated chemiluminescent immunoassay (MAG-CLIA SARS-CoV-2 Ag). METHODS The study population consisted of 181 subjects (mean age 61 ± 21 years; 92 females) undergoing coronavirus disease 2019 (COVID-19) testing at the local diagnostic facility, from December 2022 to February 2023. Routine diagnostic practice involved the collection of a double nostril nasopharyngeal swab, analyzed in duplicate with SARS-CoV-2 antigen (MAG-CLIA SARS-CoV-2 Ag) and molecular (Altona Diagnostics RealStar SARS-CoV-2 RT-PCR Kit) tests. RESULTS A significant Spearman's correlation was found between MAG-CLIA SARS-CoV-2 Ag and mean Ct values of SARS-CoV-2 E and S genes (r=-0.95; p<0.001). In all nasopharyngeal samples, the area under the curve (AUC) of MAG-CLIA SARS-CoV-2 Ag was 0.86 (95% CI, 0.81-0.90), with 0.71 sensitivity and 1.00 specificity at 7 ng/L cut-off, increasing to 0.98 (95% CI, 0.96-1.00) AUC and 0.96 sensitivity (with 0.97 specificity) in high viral load samples. When SARS-CoV-2 N protein concentration was replaced with raw instrumental readings (i.e., relative light units [RLU]), the AUC in all samples increased to 0.94. A RLU value of 945 was associated with 88.4% accuracy, 0.85 sensitivity, 0.95 specificity, 0.77 negative predictive value (NPV) and 0.97 positive predictive value (PPV), respectively. CONCLUSIONS We found satisfactory analytical performance of MAG-CLIA SARS-CoV-2 Ag, which could be used as surrogate of molecular testing for identifying high viral load samples. Broadening the reportable range of values may generate even better performance.
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Affiliation(s)
- Laura Pighi
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Brandon M Henry
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA
| | - Simone De Nitto
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | | | - Gian Luca Salvagno
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Mario Plebani
- Department of Medicine, University of Padova, Padova, Italy
| | - Giuseppe Lippi
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
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Lippi G, Henry BM, Plebani M. Diagnostic accuracy of Siemens SARS-CoV-2 Antigen (CoV2Ag) chemiluminescent immunoassay for diagnosing acute SARS-CoV-2 infection: a pooled analysis. Clin Chem Lab Med 2023; 61:1133-1139. [PMID: 36634305 DOI: 10.1515/cclm-2022-1287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 01/03/2023] [Indexed: 01/13/2023]
Abstract
BACKGROUND This article provides a critical literature review and pooled analysis of diagnostic accuracy of the fully-automated Siemens SARS-CoV-2 Antigen (CoV2Ag) chemiluminescent immunoassay for diagnosis of acute SARS-CoV-2 infections. METHODS An electronic search was conducted in Scopus, PubMed and medRxiv using the keywords ["Siemens AND CoV2Ag"] OR ["Siemens AND SARS-CoV-2 AND antigen"] for capturing studies that investigated the accuracy of Siemens CoV2Ag for diagnosing acute SARS-CoV-2 infection against a reference SARS-CoV-2 molecular test. The retrieved information was used for constructing a 2 × 2 table and for calculating pooled diagnostic sensitivity, specificity, Summary Receiver Operating Characteristic Curve (SROC) and Agreement. This study followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) reporting checklist. RESULTS Four studies totalling 1,310 respiratory samples (612 with high viral load) were finally included in our analysis. The cumulative area under the curve, accuracy, sensitivity, specificity, were 0.964 (95% CI, 0.957-0.971), 86.9% (95% CI, 84.9-88.7%), 0.79 (95% CI, 0.76-0.82) and 0.98 (95% CI, 0.96-0.99), respectively. The negative (NPV) and positive (PPV) predictive values were 0.77 (0.74-0.79) and 0.98 (95% CI, 0.96-99), respectively. The diagnostic sensitivity in samples with high viral load (i.e., Ct<29-30) was 0.95 (95% CI, 0.93-0.97). CONCLUSIONS The Siemens CoV2Ag fully-automated and high-throughput immunoassay approximates the minimum performance criteria for general SARS-CoV-2 antigen testing and displays excellent performance in samples with high viral load, thus representing a valuable screening solution for risk assessment in COVID-19 and for limiting viral spread.
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Affiliation(s)
- Giuseppe Lippi
- IFCC Task Force on COVID-19, Milano, Italy
- IFCC WG on SARS-CoV-2 variants, Milano, Italy
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
| | - Brandon M Henry
- IFCC Task Force on COVID-19, Milano, Italy
- IFCC WG on SARS-CoV-2 variants, Milano, Italy
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA
| | - Mario Plebani
- IFCC Task Force on COVID-19, Milano, Italy
- IFCC WG on SARS-CoV-2 variants, Milano, Italy
- Department of Medicine, University of Padova, Padova, Italy
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Pighi L, Henry BM, De Nitto S, Gianfilippi G, Salvagno GL, Lippi G. Real-world assessment of the clinical performance of COVID-VIRO ALL IN rapid SARS-CoV-2 antigen test. Diagnosis (Berl) 2023; 10:187-192. [PMID: 36656638 DOI: 10.1515/dx-2022-0138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 12/23/2022] [Indexed: 01/20/2023]
Abstract
OBJECTIVES Since the external validation of severe acute respiratory syndrome coronavirus 2 antigen rapid diagnostic tests (SARS-CoV-2 RDT-Ags) is a necessary requisite before they can be introduced into routine clinical practice, this study reports the results of a real-world assessment of the clinical performance of the new COVID-VIRO ALL IN device. METHODS The study population consisted in 165 outpatients (median age: 43 years, range: 14-68 years; 66.1% females) who had paired nasal and nasopharyngeal samples collected upon hospital presentation. The samples were concomitantly tested with the AAZ-LMB COVID-VIRO ALL IN SARS-CoV-2 RDT-Ag and with Cepheid Xpert Xpress SARS-CoV-2 real-time reverse transcription polymerase chain reaction (RT-PCR). RESULTS The number of subjects with positive RT-PCR results (i.e., mean Ct value <45) was 116 (70.3%), 109 (66.1%) and 86 (52.1%) with mean Ct values <37 and <30, respectively. In all RT-PCR positive samples, COVID-VIRO ALL IN displayed 78.8% agreement, 0.698 sensitivity, 1.000 specificity, 0.583 negative predictive value (NPV) and 1.000 positive predictive value (PPV) compared to RT-PCR. The median Ct value of samples testing positive with COVID-VIRO ALL IN was significantly lower than those testing negative (22.8 vs. 32.2; p<0.001). In samples with high viral load (i.e., Ct value <30), COVID-VIRO ALL IN displayed 92.1% agreement, 0.895 sensitivity, 0.949 specificity, 0.983 NPV and 0.951 PPV compared to RT-PCR. CONCLUSIONS Although the diagnostic performance of COVID-VIRO ALL IN do not exactly match those of the manufacturer, its high NPV in high viral load samples would enable fast-track and rapid identification of highly contagious subjects.
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Affiliation(s)
- Laura Pighi
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Brandon M Henry
- Medical Direction, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Simone De Nitto
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Gianluca Gianfilippi
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Gian Luca Salvagno
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Giuseppe Lippi
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
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Salvagno GL, Henry BM, Bongiovanni G, De Nitto S, Pighi L, Lippi G. Positivization time of a COVID-19 rapid antigen self-test predicts SARS-CoV-2 viral load: a proof of concept. Clin Chem Lab Med 2023; 61:316-322. [PMID: 36315978 DOI: 10.1515/cclm-2022-0873] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 10/16/2022] [Indexed: 11/09/2022]
Abstract
OBJECTIVES This proof of concept study was aimed to validate the hypothesis that the time of positivization of SARS-CoV-2 self-performed rapid diagnostic tests (RDTs) may reflect the actual viral load in the specimen. METHODS A SARS-CoV-2 positive sample with high viral load was diluted and concomitantly assayed with molecular assay (Xpert Xpress SARS-CoV-2) and RDT (COVID-VIRO ALL IN RDT). The (mean cycle threshold; Ct) values and RDT positivization times of these dilutions were plotted and interpolated by calculating the best fit. The parameters of this equation were then used for converting the positivization times into RDT-estimated SARS-CoV-2 Ct values in routine patient samples. RESULTS The best fit between measured and RDT-estimated Ct values could be achieved with a 2-degree polynomial curve. The RDT-estimated Ct values exhibited high correlation (r=0.996) and excellent Deming fit (y=1.01 × x - 0.18) with measured Ct values. In 30 consecutive patients with positive RDT test, the correlation between RDT positivization time and measured Ct value was r=0.522 (p=0.003). The correlation of RDT-estimated and measured Ct values slightly improved to 0.577 (Deming fit: y=0.44 × x + 11.08), displaying a negligible bias (1.0; 95% CI, -0.2 to 2.2; p=0.105). Concordance of RDT-estimated and measured Ct values at the <20 cut-off was 80%, with 0.84 sensitivity and 0.73 specificity. CONCLUSIONS This proof of concept study demonstrates the potential feasibility of using RDTs for garnering information on viral load in patients with acute SARS-CoV-2 infection.
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Affiliation(s)
- Gian Luca Salvagno
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Brandon M Henry
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | | | - Simone De Nitto
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Laura Pighi
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
- Service of Laboratory Medicine, Pederzoli Hospital, Peschiera del Garda, Italy
| | - Giuseppe Lippi
- Section of Clinical Biochemistry, University of Verona, Verona, Italy
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Lippi G, Henry BM, Plebani M. An overview of the most important preanalytical factors influencing the clinical performance of SARS-CoV-2 antigen rapid diagnostic tests (Ag-RDTs). Clin Chem Lab Med 2023; 61:196-204. [PMID: 36343376 DOI: 10.1515/cclm-2022-1058] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022]
Abstract
Due to the many technical limitations of molecular biology, the possibility to sustain enormous volumes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic testing relies strongly on the use of antigen rapid diagnostic tests (Ag-RDTs). Besides a limited analytical sensitivity, the manually intensive test procedures needed for performing these tests, very often performed by unskilled personnel or by the patients themselves, may contribute to considerably impair their diagnostic accuracy. We provide here an updated overview on the leading preanalytical drawbacks that may impair SARS-CoV-2 Ag-RDT accuracy, and which encompass lower diagnostic sensitivity in certain age groups, in asymptomatic subjects and those with a longer time from symptoms onset, in vaccine recipients, in individuals not appropriately trained to their usage, in those recently using oral or nasal virucidal agents, in oropharyngeal swabs and saliva, as well as in circumstances when instructions provided by the manufacturers are unclear, incomplete or scarcely readable and intelligible. Acknowledging these important preanalytical limitations will lead the way to a better, more clinically efficient and even safer use of this important technology, which represents an extremely valuable resource for management of the ongoing pandemic.
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Affiliation(s)
- Giuseppe Lippi
- IFCC Task Force on COVID-19, Milan, Italy
- IFCC Working Group on SARS-COV-2 Variants, Milan, Italy
- Section of Clinical Biochemistry and School of Medicine, University of Verona, Verona, Italy
| | - Brandon M Henry
- IFCC Task Force on COVID-19, Milan, Italy
- IFCC Working Group on SARS-COV-2 Variants, Milan, Italy
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Mario Plebani
- IFCC Working Group on SARS-COV-2 Variants, Milan, Italy
- University of Padova, Padova, Italy
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Aita A, Navaglia F, Moz S, Contran N, Barbaro F, Cattelan AM, Padoan A, Cosma C, Faggian D, Plebani M, Basso D. New insights into SARS-CoV-2 Lumipulse G salivary antigen testing: accuracy, safety and short TAT enhance surveillance. Clin Chem Lab Med 2023; 61:323-331. [PMID: 36282616 DOI: 10.1515/cclm-2022-0849] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/26/2022] [Indexed: 12/15/2022]
Abstract
OBJECTIVES The rapid, accurate and safe detection of SARS-CoV-2 is the key to improving surveillance and infection containment. The aim of the present study was to ascertain whether, after heat/chemical inactivation, SARS-CoV-2 N antigen chemiluminescence (CLEIA) assay in saliva remains a valid alternative to molecular testing. METHODS In 2022, 139 COVID-19 inpatients and 467 healthcare workers were enrolled. In 606 self-collected saliva samples (Salivette), SARS-CoV-2 was detected by molecular (TaqPath rRT-PCR) and chemiluminescent Ag assays (Lumipulse G). The effect of sample pre-treatment (extraction solution-ES or heating) on antigen recovery was verified. RESULTS Salivary SARS-CoV-2 antigen assay was highly accurate (AUC=0.959, 95% CI: 0.943-0.974), with 90% sensitivity and 92% specificity. Of the 254 antigen positive samples, 29 were false positives. We demonstrated that heterophilic antibodies could be a cause of false positive results. A significant antigen concentration decrease was observed after ES treatment (p=0.0026), with misclassification of 43 samples. Heat had a minimal impact, after treatment the correct classification of cases was maintained. CONCLUSIONS CLEIA SARS-CoV-2 salivary antigen provides accurate, timely and high-throughput results that remain accurate also after heat inactivation, thus ensuring a safer work environment. This supports the use of salivary antigen detection by CLEIA in surveillance programs.
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Affiliation(s)
- Ada Aita
- Department of Medicine - DIMED, University of Padova, Padova, Italy
| | - Filippo Navaglia
- Laboratory Medicine Unit, University Hospital of Padova, Padova, Italy
| | - Stefania Moz
- Laboratory Medicine Unit, University Hospital of Padova, Padova, Italy
| | - Nicole Contran
- Laboratory Medicine Unit, University Hospital of Padova, Padova, Italy
| | - Francesco Barbaro
- Tropical and Infectious Diseases Unit, University Hospital of Padova, Padova, Italy
| | - Anna Maria Cattelan
- Tropical and Infectious Diseases Unit, University Hospital of Padova, Padova, Italy
| | - Andrea Padoan
- Department of Medicine - DIMED, University of Padova, Padova, Italy
- Laboratory Medicine Unit, University Hospital of Padova, Padova, Italy
| | - Chiara Cosma
- Laboratory Medicine Unit, University Hospital of Padova, Padova, Italy
| | - Diego Faggian
- Laboratory Medicine Unit, University Hospital of Padova, Padova, Italy
| | - Mario Plebani
- Department of Medicine - DIMED, University of Padova, Padova, Italy
| | - Daniela Basso
- Department of Medicine - DIMED, University of Padova, Padova, Italy
- Laboratory Medicine Unit, University Hospital of Padova, Padova, Italy
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Di Gaudio F, Brunacci G, Contino F, Gallo A, Centineo F. Technical and health governance aspects of the External Quality Assessment Scheme for the SARS-CoV-2 molecular tests: institutional experience performed in all clinical laboratories of a Regional Health Service. Clin Chem Lab Med 2023; 61:173-179. [PMID: 36114825 DOI: 10.1515/cclm-2022-0780] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 09/07/2022] [Indexed: 12/15/2022]
Abstract
OBJECTIVES Since December 2019, the worldwide public health has been threatened by a severe acute respiratory syndrome caused by Coronavirus-2. From the beginning, a turning point has been the identification of new cases of infection, in order to minimize the virus spreading among the population. For this reason, it was necessary introducing a panel of tests able to identify positive cases, which became crucial for all countries. METHODS As a Regional Reference Centre, the CRQ Laboratory (Regional Laboratory for the Quality Control) developed and conducted an External Quality Assessment (EQA) panel of assay, so as to evaluate the quality of real-time reverse transcription polymerase chain reaction (PCR), which were used by 62 Sicilian laboratories, previously authorized to issue certificates for the COVID-19 diagnosis, on behalf of the Public Health Service. RESULTS The qualitative performance test was based on pooled samples with different viral loads of SARS-CoV-2 or human Coronavirus OC43. 75% of the participating laboratories tested all core samples correctly, while the remaining 25% interpreted incorrectly the EQA exercise samples matching negatively the standards required. CONCLUSIONS Subsequent inspection visits confirmed the issue of incorrect positive and negative certifications for COVID-19 by private and public laboratories, despite the possession of the authorization requirements currently provided for by current regulations, with a significant impact on the SSR.
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Affiliation(s)
- Francesca Di Gaudio
- PROMISE-Promotion of Health, Maternal-Childhood, Internal and Specialized Medicine of Excellence "G. D'Alessandro", Palermo, Italy
| | - Giuseppina Brunacci
- CQRC (Quality Control and Chemical Risk) Hospital Company, Hospitals Riuniti Villa Sofia Cervello, Palermo, Italy
| | | | - Alessia Gallo
- Department of Research, IRCCS ISMETT (Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione), Palermo, Italy
| | - Fabio Centineo
- CQRC (Quality Control and Chemical Risk) Hospital Company, Hospitals Riuniti Villa Sofia Cervello, Palermo, Italy
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Favresse J, Douxfils J, Henry B, Lippi G, Plebani M. Clinical Chemistry and Laboratory Medicine celebrates 60 years – narrative review devoted to the contribution of the journal to the diagnosis of SARS-CoV-2. Clin Chem Lab Med 2022; 61:811-821. [PMID: 36420539 DOI: 10.1515/cclm-2022-1166] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 11/16/2022] [Indexed: 11/25/2022]
Abstract
Abstract
This review is an integral part of the special issue for the 60 years of the journal Clinical Chemistry and Laboratory Medicine (CCLM). The aim of the review is to highlight the role of the clinical laboratory since the emergence of the “severe acute respiratory syndrome coronavirus 2” (SARS-CoV-2), which causes Coronavirus disease 2019 (COVID-19), with special focus on the contribution of the journal in generating knowledge in SARS-CoV-2 diagnosis. As of October 30, 2022, a total of 186 CCLM publications were dedicated to COVID-19. Of importance, major International Federation of Clinical Chemistry (IFCC) guidelines related to the diagnosis of COVID-19 were published in CCLM. Between early-2020 and late October 2022, COVID-19 publications represented around 27% of all articles in CCLM, highlighting the willingness of the editorial board to help the field in order to better describe and diagnose this new emerging disease. First launched in 1963 under the name “Zeitschrift für Klinische Chemie”, the Journal was entirely devoted to clinical chemistry in the strict sense. The various topics published in relation to COVID-19 including its diagnosis, its impact on biochemical or hematological measures, as well as biosafety measures, is the perfect example that shows that the journal has greatly diversified over time.
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Affiliation(s)
- Julien Favresse
- IFCC SARS-CoV-2 Variants Working Group , Verona , Italy
- Department of Laboratory Medicine , Clinique St-Luc Bouge , Namur , Belgium
- Department of Pharmacy , Namur Research Institute for Lifes Sciences, University of Namur , Namur , Belgium
| | - Jonathan Douxfils
- Department of Pharmacy , Namur Research Institute for Lifes Sciences, University of Namur , Namur , Belgium
- Qualiblood s.a. , Namur , Belgium
| | - Brandon Henry
- IFCC SARS-CoV-2 Variants Working Group , Verona , Italy
- Clinical Laboratory, Division of Nephrology and Hypertension, Cincinnati Children’s Hospital Medical Center , Cincinnati , OH , USA
| | - Giuseppe Lippi
- IFCC SARS-CoV-2 Variants Working Group , Verona , Italy
- Section of Clinical Biochemistry and School of Medicine, University of Verona , Verona , Italy
| | - Mario Plebani
- IFCC SARS-CoV-2 Variants Working Group , Verona , Italy
- Department of Laboratory Medicine , University-Hospital of Padova , Padova , Italy
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