The CLSI document EP19


I had occasion recently to see a final draft of CLSI EP19 – which is a framework for using CLSI evaluation documents. I may review this when it is officially released but here are three comments.

  1. There is a cause and effect diagram in EP19 listing assay attributes (precision, interferences, and so on) and the CLSI documents that are used to evaluate these attributes. I published (1) a diagram in 1992 (attributes only) and later adapted my diagram to include the associated CLSI documents and this diagram appeared in a 2002 publication (2). In 2005, I proposed to CLSI that the diagram appear in all CLSI evaluation standards – it is in EP10, EP18, and EP21 although it is not in more recent documents. Now I know that CLSI is a consensus organization whereby documents are a collaborative effort and my diagram has been modified further but there should be a citation to my prior work and there isn’t.
  2. In the clinical performance section, there is no mention of error grids (EP27). In fact, a search of EP19 shows that EP27 is never mentioned. This is most strange. After all, error grids are used to determine if an assay is good enough which is the whole point of an evaluation! Error grids are part of the FDA CLIA waiver recommended guideline and fundamental in glucose meter evaluations. I don’t understand how in years of document development of EP19, EP27 has received zero mention. I did check the list of CLSI publications on their website to make sure that EP27 is still for sale.
  3. There is mention that assay claims should clear – that’s it! no more details are given. Sadly, there was an entire document about uniformity of claims (EP11) that was killed by CLSI management after one manufacturer threatened to quit.


  1. Krouwer JS Estimating Total Analytical Error and Its Sources: Techniques to Improve Method Evaluation. 1192, Arch Pathol Lab Med., 116, 726-731.
  2. Krouwer JS Setting Performance Goals and Evaluating Total Analytical Error for Diagnostic Assays. Clin. Chem., 48: 919-927 (2002).

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