Posted by Sten Westgard, MS
A forthcoming article in CCLM asks the question, are the methods for hemostatis fit-for-purpose? or are the analytical performance specifications fit-for-purpose? And concludes that a more forgiving performance specification, for diagnosis instead of for monitoring should be used.
Determination of sigma score based on biological variation for haemostatis assays: fit-for-purpose for daily practice? Hollestell MJ, Ruinemans-Koerts J, Idema RN, Miejer P, de Maat MPM; CCLM 2019 ahead of print.
"Our study demonstrates that the majority of basic haemostatis tess do not meet APS using the median value of BV data....Thelen et al suggest using state-of-the-art criteria as an alternative, if BV criteria for the parameters do not meet the APS [ed. Analytical Performance Specifications]....Our study demonstrates that APS based on BV data is still difficult to use in the field of hemostasis."
In the Method Decision chart produced in this paper, more than 70% of the performance they measured was less than 3 Sigma. Only 7 or 17 points were above 3 Sigma, and only 2 of 24 were 6 Sigma.
This issue of goals and method performance was discussed again at the LabQuality Conference in Helsinki. The most practical remedy is Thelen et al's approach of having 2 APS goals, one from biological variation, and one from "state-of-the-art" for the analytes where the biological APS goal is unattainable.
Either we accept that, for hemostasis, all methods are unacceptable in performance. Or we accept that all methods are unacceptable in their manufacturing. And then we need a more flexible, practical, lenient APS by which to judge today's methods and laboratories.
