A reflex test in the laboratory setting is most simply defined as a test that the laboratory automatically adds on based on the result of the initial requested test, in order to optimise the diagnostic process.

Sounds like a no-brainer…

For example one might add a Hepatitis C viral load test to a sample which is positive for antibodies to Hepatitis C. Or one could add cytomegalovirus (CMV) serology to a sample which is negative for Epstein Barr virus (EBV), but with clinical and blood count parameters consistent with infectious mononucleosis. Within molecular testing, an example might be reflex testing for trichomonas in a patient who tests positive for either chlamydia or gonorrhoea. There is not so much potential for reflex testing in classical culture based bacteriology, unless of course you consider antibiotic susceptibility testing to be a reflex test, which of course it is to a certain extent. And once you delve into the field of immunology, the potential for reflex testing is massive…

The potential list of reflex tests for a clinical laboratory is actually extremely long.

So what reflex testing should be performed by the laboratory? This is actually a bit of a political hot potato.

Because everyone has their different agendas on reflex testing:

The laboratory’s view of reflex testing will depend to an extent on how they are funded. If they are funded on a fee per service/test model, they will welcome reflex testing with open arms, and utilise every opportunity to implement and encourage it. More tests equals more revenue.

If however the laboratory is funded on a “capped budget”, they will shy away from reflex testing. Extra tests in this setting means extra expenditure.

With regards to the laboratory funders, occasionally they will see that reflex testing might save them money in the long run through decreased hospital care etc. In general however, funders aren’t big fans of reflex testing, as it essentially means extra tests to fund (see idealism and realism below)

Requestors generally like the idea of reflex testing. It prevents a further consultation, further sampling etc. Anything to make the system run smoother. Occasionally though requestors get annoyed at getting a result on a test which they have not requested.

For patients also, reflex testing is generally a good thing. One must always be wary however of the consent process. Will the reflex test be included in the initial consent for laboratory testing? Personally I think that consent for laboratory testing should be on the premise that the laboratory will do “whatever it takes” to diagnose the cause of the patient’s symptoms. We don’t do test consenting very well as a rule…

Reflex testing demonstrates the difference between idealism and realism. For example 100 patients have a positive test X necessitating test Y. If test Y was reflexed by the laboratory then all 100 patients  would receive test Y. If the undertaking of test Y depended on the requestor reviewing the result of test X and actively requesting test Y, only a proportion of the 100 patients would end up getting test Y done. This is the real world.

The clinical value of reflex testing is also a continuous spectrum. For some reflex tests, the clinical value of adding on the test automatically is unequivocally high. For others the clinical value (and cost-effectiveness) is much more debatable.

Because it is such a political area, I think it is important that none of the groups above have undue influence in what reflex testing is done. Ideally a completely independent panel should set the criteria for reflex testing, and preferably on a national basis.

“No science is immune to the infection of politics and the corruption of power.”  (Jacob Bronowski)

Michael