Editorials

Assuring the quality of diagnostic tests

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f836 (Published 13 February 2013) Cite this as: BMJ 2013;346:f836
  1. Mark Wilcox, professor
  1. 1Microbiology Department, Old Medical School, Leeds General Infirmary, Leeds LS1 3EX, UK
  1. mark.wilcox{at}leedsth.nhs.uk

How do we know that they do what we think they do?

A linked investigation by Cohen and Swift (doi:10.1136/bmj.f837) clearly shows that the system for regulating the quality of in vitro diagnostic medical devices is fallible.1 The term in vitro diagnostic medical device (IVD) refers to any reagent, reagent product, calibrator, control material, kit, instrument, apparatus, equipment, or system used for the in vitro examination of human specimens. These devices underpin most medical diagnoses, so the consequences of using suboptimal products could be far reaching.

It is perhaps surprising, then, that to be marketed across Europe most IVDs require the manufacturer just to self declare that the product complies with the essential requirements of relevant European laws. Once marketed, the manufacturer has a clear responsibility to ensure that the product performs as declared. If this is in doubt, then a regulator (in the United Kingdom, the Medicines and Healthcare Products Regulatory Agency) should be informed. Cohen and Swift’s investigation shows that a system of regulating the quality of these devices that is based on trust can be undermined, especially when there is no systematic safety net to identify poor test performance. There is no evidence to suggest that many devices are flawed, but it is clear that some yield results with suboptimal clinical usefulness.2 3

CE marking is a manufacturer’s declaration that a product complies with the essential requirements of relevant European laws, permitting marketing across 30 countries. The letters …

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