Setting measurement uncertainty limits: a brief introduction to the issues

In this next of the series of articles focused on development in the application of measurement uncertainty, we discuss probably the most common question that is asked about MU. That question being — what are the limits for MU? This is a very challenging question to answer and has been a source of debate in the peer-reviewed literature for decades. Billed as the most important meeting you didn't know was happening, I couldn't wait to go to the 5th symposium of the Cutting Edge of Laboratory Medicine in Europe (CELME) meeting in Prague in October 2023.

It was clear from the outset that the intention of this meeting was not to revise the Milan Criteria (which have been referred to in previous articles, across multiple series!) for analytical performance specifications (APS), but rather to act as more of a review of how those models had been applied in the preceding decade. Rather than review the entire topic of APS, I have summarised some interesting highlights of the current understanding of APS and in particular how it is applied to the measurement uncertainty method.

Standardisation of methods requires confirmation of commutability of reference materials to patient samples. In doing so an established calibration hierarchy can be determined and results from such methods can be used interchangeably. Central to this is agreeing limits of acceptable performance so that uncertainty propagated through this traceability chain does not exceed the maximum amount allowed before clinical results are impacted.