How to Select Clinically Relevant Targets for Infectious Disease Panels | AACC.org - American Association for Clinical Chemistry (AACC)

Designing infectious disease panels isn't as easy as picking a few targets off a list and sticking them into one test. Clinical laboratories must factor in many different considerations, from the pathogens physicians are already testing for, to available laboratory equipment, to inpatient versus outpatient status. Since the COVID-19 pandemic, physicians are also more aware of the power of molecular testing.

So how should clinical laboratories approach creating and evaluating infectious disease panels? We spoke to Stella Antonara, PhD, D(ABMM), medical director of microbiology at OhioHealth Laboratory Services, about this, and about how the changing role of point-of-care testing could affect infectious disease testing in the future.

When you build a molecular panel for infectious disease testing, what are the top considerations you have to weigh?

The first thing we do is review the list of the tests our providers send out the most. What are their needs? Do they test for a specific target? We also try to be good stewards of our resources and make sure results are informing care. If we bring a test on, we look at how results will be used, and if they're going to be acted upon in a reasonable amount of time. We also ask if we'll be able to have results for our providers with a fast turnaround time, which is usually another reason to bring a test in house.

Other important considerations include how the test complements the rest of the testing we perform in house, whether we can run the test on a platform we already have, and—if yes—what other tests we can add on to this platform that we're already using. That goes back to being a good steward and utilizing resources we currently have available in the lab.

How would you advise others to approach making such decisions about these panels?

That goes back to your first question: What are you looking for when you're trying to make these types of decisions? It's utility and addressing patient needs. These decisions also depend on what kind of laboratory you are. If you're a reference lab, are you serving a big hospital system where a lot of different physicians can access the resources that you offer? Our microbiology laboratory acts as a reference laboratory for our hospital system. At the same time, we also have an extensive network of physicians' offices that we work with, so our panels would be available to them as well.

If you're an academic laboratory, you may have a niche area, and you may want to fulfill, not just clinical applications, but also research applications that dovetail with the clinical research your lab performs.

Did COVID-19 make clinicians more aware of the possibilities of molecular testing?

A silver lining of the COVID-19 pandemic is that information about clinical testing has gone out to everybody—not just to providers, but also to people in the community. People who are not laboratory oriented are using the term "PCR" left and right. So yes, it goes without saying that COVID-19 brought a lot of awareness about molecular testing to providers.

COVID-19 has also raised a lot of awareness with administrators about what we do, because they invested large sums of money to bring in new instrumentation to meet increased testing demands during the pandemic. So now everybody's looking into how we can utilize that equipment. We spent all this money—what do we do with these instruments now? How do we optimize available tests, and how do we optimize the platforms that we have. Could they be used for additional testing?

What is a clinical laboratorian's role in helping clinicians evaluate panels they might have learned about elsewhere?

Clinicians now are very astute about what laboratories can offer. Diagnostic companies are targeting them with education on different available panels.

If someone comes to us with a test request, or we find a test we think might work for our patients, we test drive it with a few of our providers and see what they think of the results. We look at how those test results would fit in their practice and what the providers found helpful about them.

Sometimes we do a study and find that yes, a test is amazing. But we've also test driven a few where something that seemed so interesting and exciting in theory was not helpful at all in clinical practice, and we decided not to implement it.

How are all these considerations different for respiratory diseases versus gastrointestinal or other disease areas?

For respiratory panels specifically, when you design a panel for outpatient populations, you can just include the four or five pathogens most commonly found in the general population. But if you're designing panels for the inpatient population, especially for those who are immunocompromised, then you'd probably want to use a panel with a lot more targets. You'd have to have a larger panel so you can look for other things that are not so common and may not apply to the general population, but that may affect hospitalized patients.

When it comes to gastrointestinal panels, there are panels that detect bacteria, viruses, and parasites all together, but there's also an option to go piecemeal, i.e., let's test first for common bacteria, then go for viruses, especially if there's a known outbreak. If those are all negative, then go for the parasitic panel. It all depends on how you approach diagnostics, and what patient population you're doing the testing for.

Regardless of what kind of panel you're using, it's important to educate providers on the large slew of organisms that can be analyzed. That's not necessarily needed for infectious disease providers, but it's important for your typical physicians' office.

Education around reimbursement is also particularly important. Insurance companies will ask why they should reimburse you for such a large panel, and what's the value if you have 15 targets versus if you have eight targets? Laboratorians can help clinicians make the right choice in these cases.

How do you collaborate with clinicians outside the laboratory when deciding on what targets/organisms should be in a panel?

In our healthcare system, we have groups that consist of each specialty who discuss best practices, not just for treatment but also for diagnostic testing. We participate on those panels. That allows us to have a relationship with the representatives in each specialty, so we can hear what they want and what they need, and if those wants and needs change over time. It also helps us understand what they might want to test for in the future, so we can research and prepare for those upcoming requests.

How has COVID-19 changed these considerations in the lab for non-COVID testing?

There's been a lot of talk about how there's going to be an explosion of point-of-care testing. Whether that will happen or not, we'll see. For example, we thought we were going to have more flu point-of-care testing that could be done at home, and we haven't.

That's not to say COVID-19 hasn't changed point-of-care testing, but new point-of-care tests are being marketed more to physicians' offices than the general public. Yes, you can do testing at home, but from what I've seen personally at least, even people who home-tested a lot during the worst of COVID-19 are going back to the provider's office for respiratory illnesses.

As for how COVID-19 has impacted infectious disease panels, I see a lot of point-of-care testing and syndromic panels for respiratory illnesses that only have a few targets—three or four of the most common things that you see being marketed towards physicians' offices. We see this as part of a trend of decentralization, which makes sense.

How does that affect the central laboratory's role? It goes back again to diagnostic stewardship, and also healthcare systems having more equipment to run tests, especially molecular tests. I think that it does help to have more sensitive assays with faster turnaround times. But even with point-of-care tests, the bottleneck is still at helping our providers with interpretation of results. Having communication channels open and participating in panels and on specialty groups that can affect policy or guidelines that are going to be put forward is crucial.