A question from Jojie Acosta:
After a lab inspection we are required to perform normal whole blood controls each day of testing for our PFA-100. Previously we only did the daily self-test on the PFA, though we ran QC on every shipment of cartridges.
We currently have difficulty finding normal donors for the required daily QC during off shifts or on weekends. Also the number of suitable normal donors are limited. Any suggestions on how to address the required daily QC for the PFA-100? Normal donors are hard to find.
Dear Jojie Acosta, thank you for your question. You don’t identify who performed your lab inspection, but I think the assessor may have been working from a missed or obsolete communication. The package insert for the PFA-100 specifies “wet QC” on new lots only, thus you were doing your QC correctly. You may wish to contact your Siemens representative in case you need additional documentation. Good luck with the inspection team! Geo.
I agree. Often, inspection teams “inspect” you against what
I agree. Often, inspection teams “inspect” you against what they do in their lab and not against what’s in the checklist. I’d challenge the deficiency.
The question of daily QC for platelet function testing is co
The question of daily QC for platelet function testing is contentious. The laboratory assessor was probably working to the current CLSI guidelines for platelet function testing (Christie DJ, Avari T, Carrington LR, et al. Platelet Function Testing by Aggregometry; Approved Guideline. CLSI document H58-A. Wayne, PA: Clinical and Laboratory Standards Institute (CLSI); 2008). Nevertheless, whilst the testing of a normal individual within every day of testing using a PFA-100 would similarly represent a preferred practice, George is correct in his comment related to the product insert, and that this practice should not be considered as mandatory. First, the CLSI document is meant to cover primarily Platelet Function Testing by Aggregometry rather than PFA-100 testing, and second the document is a guideline based largely on consensus opinion (ie the guideline is not a mandatory standard). The requirement for QC for the PFA-100 is as stated in the product insert and as noted by George. My own view is that it is probably more important to actually assess the instrument’s performance at the ‘abnormal closure time’ region, since in our experience, a normal closure time is less likely to be a false normal closure time than a prolonged closure time is likely to be a false prolonged closure time. Thus, it makes more sense to run a normal control when the laboratory does not obtain normal closure times after testing of patient samples, just as it makes sense to run a normal control when the laboratory obtains a significantly abnormal platelet function test by aggregometry. Moreover, I would argue that running a normal control with each series of platelet function tests including the PFA-100 is only 20% of the story. Ideally, you should be running several abnormal controls as well. However, it is ethically inappropriate to force laboratory staff and well characterized patients to continually donate blood for this purpose and it is simply impossible from a practical perspective to incorporate the true range of potential abnormal patterns reflected by platelet function abnormalities into the quality control process for platelet function procedures. For any interested readers, the problems associated with internal QC and external QC of platelet function testing is extensively discussed elsewhere (Favaloro EJ. Internal Quality Control and External Quality Assurance of Platelet Function Tests. Semin Thromb Hemost 2009, 35: 139149.)