A recent Letter in Clinical Chemistry (2007;53:1715-1716) is another in the series that advocates using the right model for assay analytical performance (see this essay). Unfortunately, I didn’t see an error in the proofs. The sentence, “Because neither controls nor pooled samples are used in a proficiency survey, random patient interferences cannot be estimated.” Should be “Because either controls or pooled samples are used in a proficiency survey, random patient interferences cannot be estimated.”
This Letter is about creatinine and the authors replied (2007;53:1716-1717). All of this is quite similar to an earlier Letter about glucose in Clinical Chemistry (2001;47:1329-30) and the authors’ reply (2001;47:1330-31).
Using the right model creates some experimental difficulties, but it is still worth it.