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How to Validate an Aggregometer

From Rrosales:

I am interested in purchasing a platelet aggregometer for our hematology lab, but we don’t have an existing instrument to compare it with. Some suggested H58 NCCLS (CLSI, does not really help) but I am used to validating an instrument with an old instrument (comparison/parallel testing). Can you tell me how to start the validation without an instrument to compare it with and does CAP allows this method?

Hello, and thanks for your question. Because aggregometry is essentially a qualitative procedure, validation is relatively simple. Typically, when you purchase an aggregometer, your representative will assist you with its validation, either by comparing to a calibrated instrument or the instrument of a nearby client. The rep will be acquainted with CAP and CMS requirements. Though I don’t mean to endorse a particular instrument, I suggest you contact Kathy Jacobs from Chronolog, Inc, whose post appears just below this one. Kathy and the Chronolog staff are experts.

Comments (2)
Platelet Function Testing
Mar 13, 2014 2:53pm

We have recently validated our platelet aggregometetr and ha
We have recently validated our platelet aggregometetr and have experienced exactly what you describe. Quantitative analysis shows some variability of results between our old aggregometer and our new one, but the interpretation of the platelet aggregation test is qualitative and the observed quantitative differences in my view are not clinically significant; they would not lead me to conclude that someone has a platelet disorder after running the sample on one instrument as opposed to the other.

May 4, 2012 8:23am

We addressed this issue with Trudy Darden @
We addressed this issue with Trudy Darden @ CAP a couple of years ago. Her response to us was as follows: The requirements for validation of new instruments can be found in the CAP General checklist. However, many of these requirements will not apply to platelet aggregometers due to the nature of the test. There are no commercial controls available for this instrument. The manufacturer recommends that a normal range study be performed using 20-50 “normal” samples. The manufacturer provides broad guidelines regarding where this range should fall. The laboratory must define the normal population they will be using for this study. The number of samples is the discretion of the medical director. Since there are no commercial controls available, an accuracy study cannot be performed. The laboratory can perform a precision study however, because the normal samples can be repeated for precision. The manufacturer provides guidance for interferences (low platelet counts) and to discontinue the test after 6 minutes.

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