Dear Reza and Chris
This has also caused us severe problems. We have previously had problems with the Ca 153 assay which were traced to the instrument mechanics so that when we noticed a positive shift in IQC along with problems with another assay we spent a great deal of time and effort in trying to locate the source of the problem. Whilst we were doing this we informed our clinicians of the problem and made safe all samples. Eventually we were told by Siemens that they had re-calibrated the assay which had resulted in an IQC shift of +14% and a small patient sample shift below the reference range. We verified that our IQC shift was about 14% and like Chris measured a set of old EQA samples which suggested that there was no significant change in patient sample results. Total down time was a week, BMS troubleshooting time was considerable.
This seems to be a recurring scenario!
Best wishes
Douglas
Dr D Thompson
Principal Biochemist
Clinical Biochemistry and Immunology
The General Infirmary
Leeds LS1 3EX
Tel 0113 3926503
Please visit our web-site at www.leedsteachinghospitals.com
>>> Reza Morovat <[log in to unmask]> 11/3/09 16:40 >>>
Dear Chris,
Thanks for alerting us. There is indeed a positive bias. According to our re-running of IQC (we use BioRad's) and old EQA specimens, the bias has a mean of around 20% (with new lot 137 vs. the old 136). Consequently, we're not reporting any CA15-3 until I hope we manage to assess the change over a much longer period (i.e. how did 136 compare with the previous lot?), and decide upon an acceptable interim measure.
Best wishes,
Reza
Reza Morovat
Clinical Biochemist
Oxford
Date: Thu, 5 Mar 2009 17:01:02 +0000
From: [log in to unmask]
Subject: Ca153 assay on Centaur
To: [log in to unmask]
Ca153 assay on Centaur
Apologies if this has already been queried but I wonder whether other Centaur users are experiencing any problems with their Ca153 assay quality control? The message we get from the manufacturer is that our observed positive bias on IQC (increased some 25-30%) will not be reflected in changes to patient results. Re-run EQA does seem to behave in a similar fashion to IQC though and unfortunately we have no way of going back to previous patient samples to assess.
Chris
------------------------------------------------
Chris Sergeant
Principal Biochemist
Clinical Biochemistry
BHR NHS Trust
Ext. 8318
Direct: 0208 970 8318
------------------------------------------------
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