Few in the clinical laboratory community would argue with the proposition that diagnostic tests are best when they offer the shortest possible time to result.
Obtaining test results quickly means that healthcare providers can immediately initiate diagnosis-specific treatment for those whose results are positive. In some instances, treatment can be started even before the patient leaves the point of care—thereby reducing the potential for both loss to follow-up and continued transmission of infectious diseases.
Quicker test results also offer public health benefits, including better population screening and faster response to public health emergencies. As described by James Cottam, PhD, in this month’s Inside Track column (page 34), such tests are playing a key role in limiting the spread of antibiotic resistance, now seen as a major threat to public health in every region of the world.
While advanced diagnostic technologies may offer other advantages, so-called “rapid diagnostic tests” (RDTs) remain at the forefront when it comes to producing test results quickly. First commercialized in the 1980s, RDTs were aptly named for their speed in comparison with traditional culture tests. Moreover, RDTs generally offer other characteristics that make them desirable in a wide variety of settings: they are stable in most environmental conditions, inexpensive, easy to use with little training, readily portable to the point of care, and accurate—mostly.
But for some RDTs, getting to accuracy is something of a struggle. Uninstrumented RDTs are known for being less sensitive than comparable laboratory-based tests, and for providing ambiguous results requiring professional interpretation. Among the most troubled of RDTs are those called “rapid influenza detection tests,” the earliest of which received market clearance in 1990. During and since the swine flu pandemic of 2009, clinicians and scientists have raised concerns about the poor sensitivity of such tests, leading FDA to convene a microbiology advisory panel in June 2013 to discuss new regulatory requirements.
The upshot of this process has now appeared in a Federal Register notice of May 22, in which FDA proposes to upclassify rapid influenza detection tests from Class I to Class II, creating a new device classification for such products called “influenza virus antigen detection test systems.” The special controls required for the new category would establish performance standards as well as procedures for keeping the tests current with mutations in the influenza genome over time.
Rapid time to result remains a significant and desirable benefit, but creating influenza tests that can meet FDA’s new sensitivity and specificity requirements will be an important and challenging achievement.
The public comment period on FDA’s proposal (Docket no FDA-2014-N-0440) will run through August 20, 2014.
Steve Halasey
Chief Editor, CLP
[email protected]
(626) 219-0199
