On the other hand...

I've been pretty critical of hospitals' reluctance to make use of rapid diagnostics to improve patient care. And I think that this criticism has been well-deserved. But these tests do have some shortcomings, and it's only fair to take note of them.

Limited reportable results. Most rapid tests only identify a single organism. An exception is the Verigene Gram-positive Blood Culture Test, which returns ID results for 9 species. Limited results mean that labs still have to do a full workup in order to identify organisms not covered by the rapid test. Rapid testing therefore doesn't replace any test; instead it adds to workload and cost.

Resistance but not susceptibility. Rapid tests, with one exception, detect sequences or products from resistance genes such as mecA or vanA/B. A positive result thus (usually but not always) indicates a resistant phenotype. But when resistance rates are at 30% or 40% or even more, doctors tend to presume resistance and prescribe accordingly before receiving test results. Thus the clinical value of a positive result for resistance is somewhat limited - the patient is likely already on the antibiotic indicated by the test as being appropriate. And then, a negative result for a resistance gene is just that - it means a certain gene (actually just a small target segment of it) is missing or altered, but it does not necessarily follow that the organism will be susceptible to the antibiotic in question. Of the rapid tests, only the MicroPhage test was cleared to return a susceptibility result which would enable a change in therapy. And it is no longer available.

So there are some legitimate reasons to hold off on adoption of rapid testing. But they still are outweighed by the benefits to the patient, and to the healthcare system as a whole. You don't have to save many ICU days to pay for a whole lot of testing. But the savings are often diffuse and indirect and accrue to payors outside the hospital, while the costs are borne by the lab making the purchasing decision. Viewed from this perspective, it's not hard to see why adoption of rapid testing has been so slow.

Posted with Blogsy