Posted by Sten Westgard, MS
Readers may recall an earlier lesson we posted in June titled, Would your laboratory have caught this error?
It generated quite a bit of reader interest, but coincidentally, a recent article published in Clinical Chemistry has reported that the laboratory in question was not alone:
As it turns out, the Mayo Clinic and the University of Virginia Medical Center were experiencing similar problems with the same method. Mayo Clinic estimated that if 1,000 patients were being tested per month, they were possibly generating 50 false-positive results, causing extra testing, care, delay, confusion, and anxiety. In an era where health systems are seeking and try to eliminate waste, having a test that causes such problems is a cardinal sin. It appears this method error persisted for multiple years. That's a lot of false positives and a lot of financial cost to a health system, even if it's not easy to tally up on a balance sheet.
What's more concerning and interesting about the recent study is that the usual lot-to-lot reagent tests were not able to catch the growing problem. The typical approach, to test a few patient samples on both old and new reagent lots, was not able to detect the problem - the study authors estimate they would have needed hundreds of patient specimens in a crossover study in order to be able to detect the problem. Which is not practical, even for large volume laboratories.
Ultimately, what we see is that the problems get much harder to handle once they reach the customer (the lab) - it would be far easier if the manufacturer was doing a better job in the first place: monitoring the method quality and the reagent quality. And if the manufacturer wasn't monitoring this, then some type of external quality assurance group needs to be able to detect these problems (possibly with accuracy-based samples).
I guess the obstacle to getting manufacturers to monitor their quality more closely is that it becomes a self-selecting problem: the manufacturers wih the worst quality are the manufacturers least likely to want to monitor their own quality or talk about quality to their customers. Somehow, the manufacturers need a nudge in the correct direction.
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