Marc Wirden1, Linda Feghoul2, Mélanie Bertine3, Marie-Laure Nere4, Quentin Le Hingrat3, Basma Abdi1, David Boutolleau1, Valentine Marie Ferre3, Aude Jary1, Constance Delaugerre5, Anne-Genevieve Marcelin1, Diane Descamps3, Jérôme Legoff2, Benoit Visseaux3, Marie-Laure Chaix6. 1. Sorbonne Université, INSERM, Institut Pierre Louis d'Epidémiologie et de Santé Publique IPLESP, AP-HP, Hôpital Pitié-Salpêtrière, Laboratoire de virologie, Paris, France. 2. Université de Paris, Département des Agents Infectieux, Service de Virologie, Hôpital Saint-Louis, Paris, France; INSERM UMR 976, Université de Paris, Paris, France. 3. Université de Paris, Assistance Publique - Hôpitaux de Paris, Service de virologie, Hôpital Bichat, Paris, France; UMR 1137-IAME, DeSCID: Decision SCiences in Infectious Diseases control and care, INSERM, Université de Paris, Paris, France. 4. Université de Paris, Département des Agents Infectieux, Service de Virologie, Hôpital Saint-Louis, Paris, France. 5. Université de Paris, Département des Agents Infectieux, Service de Virologie, Hôpital Saint-Louis, Paris, France; INSERM UMR 944, Université de Paris, Paris, France. 6. Université de Paris, Département des Agents Infectieux, Service de Virologie, Hôpital Saint-Louis, Paris, France; INSERM UMR 944, Université de Paris, Paris, France. Electronic address: marie-laure.chaix@aphp.fr.
Abstract
BACKGROUND: RT-PCR testing is crucial in the diagnostic of SARS-CoV-2 infection. The use of reliable and comparable PCR assays is a cornerstone to allow use of different PCR assays depending on the local equipment. In this work, we provide a comparison of the Cobas® (Roche) and the RealStar® assay (Altona). METHODS: Assessment of the two assays was performed prospectively in three reference Parisians hospitals, using 170 clinical samples. They were tested with the Cobas® assay, selected to obtain a distribution of cycle threshold (Ct) as large as possible, and tested with the RealStar assay with three largely available extraction platforms: QIAsymphony (Qiagen), MagNAPure (Roche) and NucliSENS-easyMag (BioMérieux). RESULTS: Overall, the agreement (positive for at least one gene) was 76 %. This rate differed considerably depending on the Cobas Ct values for gene E: below 35 (n = 91), the concordance was 99 %. Regarding the positive Ct values, linear regression analysis showed a coefficient of determination (R2) of 0.88 and the Deming regression line revealed a strong correlation with a slope of 1.023 and an intercept of -3.9. Bland-Altman analysis showed that the mean difference (Cobas® minus RealStar®) was + 3.3 Ct, with a SD of + 2.3 Ct. CONCLUSIONS: In this comparison, both RealStar® and Cobas® assays provided comparable qualitative results and a high correlation when both tests were positive. Discrepancies exist after 35 Ct and varied depending on the extraction system used for the RealStar® assay, probably due to a low viral load close to the detection limit of both assays.
BACKGROUND: RT-PCR testing is crucial in the diagnostic of SARS-CoV-2 infection. The use of reliable and comparable PCR assays is a cornerstone to allow use of different PCR assays depending on the local equipment. In this work, we provide a comparison of the Cobas® (Roche) and the RealStar® assay (Altona). METHODS: Assessment of the two assays was performed prospectively in three reference Parisians hospitals, using 170 clinical samples. They were tested with the Cobas® assay, selected to obtain a distribution of cycle threshold (Ct) as large as possible, and tested with the RealStar assay with three largely available extraction platforms: QIAsymphony (Qiagen), MagNAPure (Roche) and NucliSENS-easyMag (BioMérieux). RESULTS: Overall, the agreement (positive for at least one gene) was 76 %. This rate differed considerably depending on the Cobas Ct values for gene E: below 35 (n = 91), the concordance was 99 %. Regarding the positive Ct values, linear regression analysis showed a coefficient of determination (R2) of 0.88 and the Deming regression line revealed a strong correlation with a slope of 1.023 and an intercept of -3.9. Bland-Altman analysis showed that the mean difference (Cobas® minus RealStar®) was + 3.3 Ct, with a SD of + 2.3 Ct. CONCLUSIONS: In this comparison, both RealStar® and Cobas® assays provided comparable qualitative results and a high correlation when both tests were positive. Discrepancies exist after 35 Ct and varied depending on the extraction system used for the RealStar® assay, probably due to a low viral load close to the detection limit of both assays.
Authors: Emma Davies; Hamzah Z Farooq; Benjamin Brown; Peter Tilston; Ashley McEwan; Andrew Birtles; Robert William O'Hara; Shazaad Ahmad; Nicholas Machin; Louise Hesketh; Malcolm Guiver Journal: Clin Lab Med Date: 2022-03-08 Impact factor: 2.172
Authors: Fausto Baldanti; Nirmal K Ganguly; Guiqiang Wang; Martin Möckel; Luke A O'Neill; Harald Renz; Carlos Eduardo Dos Santos Ferreira; Kazuhiro Tateda; Barbara Van Der Pol Journal: Crit Rev Clin Lab Sci Date: 2022-03-15 Impact factor: 6.250