The changing respiratory testing landscape: Why the value of flexibility is key

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LEARNING OBJECTIVES

Upon completion of this article, the reader will be able to:   

1. Identify the goal of developing appropriate diagnostic respiratory testing panels.

2. Differentiate the key factors in the development of testing workflows for diagnosing respiratory illness.

3. Identify the goals of creating a diagnostic stewardship program for respiratory illnesses.

4. Discuss the different options in choosing the right testing algorithms for the diagnosis of respiratory illness.

In the post-pandemic era of respiratory testing, laboratories need to consolidate platforms and assays to accomplish more with less all while ensuring sufficient testing menus for meeting clinical needs.1 At the same time, there is growing pressure to align testing procedures with a changing landscape of diagnostic stewardship protocols and ensure that each patient gets the right test at the right time to generate meaningful information that influences appropriate clinical decisions. Ultimately, the goal is to lead to both better patient outcomes and reduce unnecessary testing that increases healthcare costs without producing actionable results.2

Achieving these goals simultaneously will be a significant challenge for the clinical laboratory community. However, it’s never too early to begin planning for seasonal respiratory testing as a year-round strategy. This is key for ensuring flexible testing algorithms. The most important factor in today’s respiratory testing is flexibility in workflows. Fixed testing products such as broad syndromic panels make it far more difficult to tailor testing to each patient’s needs, and their fixed costs are not conducive to lowering laboratory bills.

Given the multitude of respiratory pathogens as well as clinical, epidemiological, and economic factors, testing for respiratory infections involves a high degree of complexity and burden. Differences in seasons, patient demographics, severity of disease, specimen type, suspected pathogen type, and more can influence the testing process.1,3 

Several key factors4,5 that must be considered for respiratory testing workflows include the following:

Seasonality: Respiratory testing algorithms are highly influenced by co-circulating respiratory pathogens that may follow a seasonal pattern, such as influenza viruses and respiratory syncytial virus (RSV), while other respiratory infections may present opportunistically in season following a flu infection, such as bacterial pneumonia caused by Staphylococcus aureus or Hemophilus influenzae. In these seasonal scenarios, typical outpatients with less severe symptoms may require standard targeted flu A/B and RSV testing; hospitalized patients with more severe symptoms could require a broader panel-based test. Conversely, a combination of targeted seasonal testing and reflex testing to a panel-based syndromic approach for patients with ongoing disease or pediatric patients may be warranted.

Out-of-season testing is largely driven by symptoms and etiological risk factors such as travel and/or exposure. As examples, targeted testing for COVID-19, group A streptococcus, and Bordetella pertussis might be warranted in some cases, while a syndromic panel approach might be needed based on disease risk or severity. 

Patient needs: Regardless of season or the regional epidemiological landscape, patient demographics can require different levels of testing. The presence of common respiratory pathogens may be affected by age (e.g., RSV for children or the elderly), health status (e.g., immunocompromised or severe pneumonia), and vaccination status. Single-pathogen tests or targeted mini-panels might be appropriate for an otherwise healthy adult, but an immunocompromised patient, an elderly patient, or a child might require a broader approach — and typically a different broader approach for each of these types of patients depending on their exact clinical situation.

Pathogen type: In some situations, such as during a COVID-19 community surge, it may be safe to assume that the pathogen responsible for a patient’s respiratory infection is the SARS-CoV-2 virus, so starting with a targeted test would be justified. However, for immunosuppressed individuals or patients with, or at risk for, critically ill respiratory disease, a syndromic approach makes for better clinical utility given the multitude of potential pathogens causing similar symptoms. Identifying the correct pathogen is essential for ensuring appropriate therapy and avoiding prolonged disease or mortality.

Diagnostic stewardship

Applying appropriate clinical and epidemiological factors to select the right test for the right patient at the right time allows laboratory medicine specialists to align with the principles of diagnostic and antimicrobial stewardship.2,6

Laboratory interventions to guide clinical testing and patient management are key, given that most healthcare decisions today are based on diagnostic tests. This is a testament to the importance of clinical laboratories in patient care, but it also puts laboratory testing front and center in efforts to reduce healthcare costs by ensuring appropriate testing and prompting the right healthcare actions.

For respiratory testing, where symptoms in many cases are very similar, diagnostic stewardship aims to deliver appropriate testing algorithms in order to fast-track clinical decisions and facilitate appropriate treatments for patients while reducing the unnecessary use of antibiotics or antivirals. Another aim, less important for patient care but just as important for the responsible management of healthcare costs on behalf of patients, is to get the right clinical information quickly at the lowest possible price point. A lab that relies on fixed syndromic panels for all suspected respiratory infections, regardless of patient demographics or seasonality, might offer a comprehensive testing approach but fail to meet the goals of diagnostic stewardship.

Choosing the right test

Going forward, post-pandemic respiratory testing algorithms are already taking shape based on clinical, epidemiological, and economic factors. Appropriate strategies will enable optimal patient outcomes without wasteful and costly testing or treatment while facilitating laboratory profitability and alleviating hospital burdens. In addition, simplicity and flexibility in testing algorithms will help reduce the burden on ordering physicians and laboratory staff.

While many labs have adopted targeted testing for differential diagnosis of common respiratory pathogens, others have adopted flexible testing approaches based on syndromic panels. A flexible syndromic method allows for the creation of targeted custom panels as subsets of the broader syndromic panel. In this model, labs pay only for the results they select from the broader test.7,8 Should all results of an initial grouping come back negative, staff may choose to view results for more targets on the syndromic panel without re-running the assay. This is accomplished through software manipulation rather than as part of the assay workflow. This flexible approach makes it possible for laboratory staff to use a streamlined syndromic algorithm for their unique test situations, minimizing the need for training and validation while meeting the diagnostic stewardship goal to avoid over-testing.

For example, some laboratories begin with syndromic panels of about 20 respiratory pathogens, from which they select targeted groupings that can be used for a more customized testing approach. One grouping might include viral and bacterial pathogens that cause similar symptoms. Others might represent the full range of testing needs based on patient demographics, such as a targeted panel of influenza A/B and RSV for a pediatric patient, or a broader group of viral targets for an immunocompromised patient. These groups can also be used as a reflex when singleplex testing is negative either on the same platform or a different platform.

Alternatively, a successful approach for clinical labs is to run respiratory tests on one platform, eliminating the need to bring in multiple platforms to handle all pathogens, all throughputs, and all price points. 

What’s next

The confluence of endemic COVID-19, diagnostic stewardship programs, and rising healthcare costs has led to more complexity than ever in the world of respiratory testing. Laboratories must decide when to test which patients for which pathogens, and then be prepared to justify the costs of those decisions — all on a patient-by-patient basis.

Regardless of which diagnostic platforms a clinical laboratory chooses to implement, the most important factors in meeting these different goals should be simplicity, flexibility, and test appropriateness. In planning for future respiratory testing, laboratory leaders will want to prioritize testing options based on clinical and epidemiological factors that align with their institutional needs and allow for the championing of the quest for diagnostic stewardship and optimized healthcare. Targeted respiratory testing or flexible syndromic panel testing can fit nicely into this approach, addressing reimbursement concerns, and managing costs without an overly complicated workflow. 

Ultimately, clinical laboratories have a unique opportunity within the changing post-pandemic respiratory landscape to ensure diagnostic stewardship principles for respiratory testing practice and beyond. Collectively, these initiatives will drive appropriate clinical and economic outcomes against ongoing healthcare challenges. 

References

1.      Wichmann C. (2023, July 13). Right patient, right test, and lab efficiency. Medical Lab Observer, 55 (8), 42. https://www.mlo-online.com/management/careers/article/53063478/right-patient-right-test-and-lab-efficiency.

2.      World Health Organization. (2016). Diagnostic stewardship: A guide to implementation in antimicrobial resistance surveillance sites [Technical document]. https://www.who.int/publications/i/item/WHO-DGO-AMR-2016.3.

3.      Chow EJ, Uyeki TM, Chu HY. The effects of the COVID-19 pandemic on community respiratory virus activity. Nat Rev Microbiol. 2023;21, 195–210. https://doi.org/10.1038/s41579-022-00807-9.

4.      Calderaro A, Buttrini M, Farina B, Montecchini S, De Conto F, Chezzi C. Respiratory Tract Infections and Laboratory Diagnostic Methods: A Review with A Focus on Syndromic Panel-Based Assays. Microorganisms. 2022; 10(9):1856. https://doi.org/10.3390/microorganisms10091856.

5.      Albert C. (2023, October). Looking ahead to respiratory virus season. CAP Today, 37 (10), 1,24.

https://www.captodayonline.com/looking-ahead-to-respiratory-virus-season/.

6.      Claeys KC, Johnson MD. Leveraging diagnostic stewardship within antimicrobial stewardship programmes. Drugs Context. 2023;12:2022-9-5. Published 2023 Feb 20. doi:10.7573/dic.2022-9-5.

7.      Silva A. (2016). Flexible Respiratory Pathogen Testing: Why Clinical Laboratories No Longer Have to Settle [White paper]. Luminex. https://us.diasorin.com/sites/default/files/products-documentation-tool/WP103759.VERIGENE.RPFlex.Silva.v2.WR.pdf.

8.      Lopansri B. (2016). Expert Commentary: A Clinician’s Perspective on Flexible Testing [Case study]. Luminex. https://us.diasorin.com/sites/default/files/products-documentation-tool/CASE147747.Clin.FlexTesting-CASE9181.WR.pdf.

9.      Centers for Disease Control and Prevention. (2023). RSV in Infants and Young Children. U.S. Department of Health and Human Services, National Center for Immunization and Respiratory Diseases. https://www.cdc.gov/rsv/high-risk/infants-young-children.html.

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