The issues in CDI testing
While there are diagnostic tests for CDI, some are regarded as too sensitive and others not sensitive enough. In the hunt for a "just right" solution, healthcare professionals generally have their own preferences when it comes to testing for CDIs. However, without a clear consensus on CDI testing guidelines, conflicting recommendations have escalated these opinions into a full-scale controversy.
There are two major choices of technology when it comes to CDI detection. Historically, the most common is enzyme immunoassay (EIA). While this option is fast and relatively inexpensive, those opposed to using it for CDI diagnosis worry about its lack of sensitivity. This lower sensitivity could mean that patients are left untreated, at risk of serious illness and death, and could spread infection to others.
The other option, nucleic acid amplification testing (NAAT), detects the presence of C. difficile colonization and is known for its superior sensitivity. With NAAT, the concern is that, because colonization does not necessarily translate to actual infection, the test is too sensitive and results in patients being treated with antibiotics unnecessarily. This increases the risk of antibiotic resistance, and of recurrent CDIs.
There have been attempts to address each technology’s shortcomings by combining them, for example using algorithm-based diagnoses, but these have their own issues and overall, the currently available choices for diagnosing CDI are less than ideal.
Rising to the challenge
Ultra-sensitive immunoassay could bridge the gap by delivering both sensitivity and precision. Diagnostic start-ups such as Quanterix and Singulex are developing an ultra-sensitive immunoassay test. Promising progress has been made, as in October 2018 the Singulex Clarity ultra-sensitive immunoassay test for CDI was registered with the FDA as a Class I device.
Whether this new technology, or any other, will be the answer to the CDI diagnostics controversy remains to be seen. Given the potential impact of a misdiagnosis on the patient's journey, clinicians and laboratory staff may be hesitant to trust a novel technology until they can see completely convincing evidence. Until then, the new technologies will compete against the already-proven options of EIA and NAAT.
Ringing in the new
Introducing a new way to diagnose CDI, changing the minds of healthcare and laboratory professionals, and driving adoption will require a multi-faceted approach, based around education, support, and affordability.
The process must be based on evidence from clinical outcome studies, which can be used to support value propositions and guideline changes. Garnering physician support and creating demand will rely on increasing awareness for the new option, through key opinion leaders, professional groups, conferences, and publications. Success, however, in a time of budget constraints, will depend on the availability of reimbursement.