We've now seen a similar effect. We were sent samples that were close to the Abbott cut-off, and we ran them on the Roche assay. There was a lack of agreement for quite a few samples, tending towards more positives with the Roche assay, and with pos/neg results further from the cut-off. I don't have any clinical details.
Tanya
Tanya Hart PhD FRCPath
Principal Clinical Scientist
Department of Clinical Biochemistry
Poole and Royal Bournemouth Hospitals
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of SHARROD-COLE, Hayley (THE ROYAL WOLVERHAMPTON NHS TRUST)
Sent: 22 June 2020 11:56
To: [log in to unmask]
Subject: Comparisons between the Roche and Abbott SARS-CoV-2 antibody assay
Dear Collective,
We have also been able to run some comparisons between the Roche and Abbott assays and have also seen discordant interpretation in the samples identified as 'weak positives' on the Roche assay. Samples in this region are typically negative by the Abbott assay. For our lab this could equate to detection of 5% fewer 'positive' results than a Roche lab.
The numerical values from the Roche assay are up to 10 fold higher in 'positive' samples which I don't think can be explained solely by the different antibody isotype detection by the two assays, although I accept the knowledge of the immune response to this virus is not yet fully understood.
Does anyone have any thoughts on this?
Hayley
Hayley Sharrod-Cole FRCPath
Principal Clinical Scientist
Black Country Pathology Services
Supporting: The Royal Wolverhampton NHS Trust
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of ACB-CLIN-CHEM-GEN automatic digest system
Sent: 22 June 2020 00:05
To: [log in to unmask]
Subject: ACB-CLIN-CHEM-GEN Digest - 20 Jun 2020 to 21 Jun 2020 (#2020-148)
There is 1 message totaling 96 lines in this issue.
Topics of the day:
1. Comparisons between the Roche and Abbott SARS-CoV-2 antibody assay
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Date: Sun, 21 Jun 2020 21:38:10 +0100
From: Gavin Murdock <[log in to unmask]>
Subject: Comparisons between the Roche and Abbott SARS-CoV-2 antibody assay
Hi all
We were able to participate in a sample exchange with a lab running the
Abbott assay (we use the Roche assay) which has allowed us to look at the
concordance between the Roche and Abbott antibody assays.
There were only 21 samples in total.
In summary:
- All the samples negative by the Roche assay were negative by the
Abbott assay
- All the strongly positive samples by the Roche assay (defined as > 60
COI in this sample) were also positive by the Abbott assay.
- Disagreement appears to be over what I would describe as weak
positives. These were samples with results on the Roche assay in the range
1 - 5 COI. They were all, apart from one, negative by the Abbott assay.
I believe that the Abbott assay is specific for IgG nucleocapsid antibodies
whilst the Roche assay should detect all nucleocapsid antibody isotypes.
This seems like one obvious reason for the discrepancy.
I thought I'd share to add to the data in this area.
I'll be interested to see what the EQA schemes show.
A lab in Vienna has posted the results of its comparison of the Roche,
Abbott and DiaSorin assays - https://doi.org/10.1101/2020.06.04.20117911
Regards,
Gavin
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