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How Many QC Repetitions?

From Heather DeVries at Indiana University Health. Hello George! In a system meeting recently, our procedure for evaluating new lot calibrator material was discussed. Currently, we require sites to run 5 points of QC after calibrating with a new lot. If the mean of those 5 points is within 20% of the established mean, we are done.  If there is a shift where the mean is >20% different, we require sites to run 20 total points over 3 days to re-establish mean. Smaller sites consider this a waste of reagent, even though I don’t believe we have ever had to run 20 points. Even 5 points seems too much for them. How do other facilities handle new lot calibrator material? Thanks!

Hi, Heather, and thank you for your question. Am I correct to conclude the 5 points of QC, or the 20 points, when necessary, refers to control material, which, along with reagents to run the assays seems like a modest use of materials, but I’d like to learn what our participants are doing. Geo.

Comments (1)
Sep 13, 2016 1:35am

I guess it also depends on
I guess it also depends on what assay you are performing and whether you are using kit provided controls or a third party QC material. If you use the latter, even a single QC point for normal and pathological/therapeutic (depending on the assay) will provide some preliminary information. But I would agree that the process outlined should help establish progressive bias, and whether a new mean needs to be established. If you use only kit provided controls, then no number of data points will tell you whether any shift has occurred, and you will probably need to establish a new mean for the ‘new kit’ controls anyway.

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