Flexible testing can help navigate the latest IDSA guidelines for C. diff infections

While scientific developments and perceived clinical significance are what fundamentally drive breakthroughs in the healthcare world, it is widely accepted that reimbursement is a key factor in determining which products make it to market, as well as how accessible those products are to both healthcare providers and the patients who need them.1 Additionally, investment in and development of healthcare drugs, technologies and medical devices often hinge on uncertain circumstances, such as the future need for a product, and how actions by health coverage programs will drive future reimbursement for a technology. Taken together, these factors create a cycle in which reimbursement policies compete with clinical need to determine which healthcare technologies or pharmaceuticals are invested in and developed.

Social health coverage programs and private health insurance plans—or payers—such as the Centers for Medicare and Medicaid Services (CMS) are the key drivers for establishing reimbursement policies. They define what therapeutics and technologies will be covered as part of beneficiary services, as well as what terms must be met in order to receive that coverage.1 Once CMS establishes these terms, private payers may incorporate publicly available policy information to determine the scope of their healthcare coverage, adding an additional loop to the healthcare cycle.

Flexible testing is one of the latest solutions for navigating reimbursement challenges, dwindling resources and time-consuming diagnostic procedures. As it becomes more widely available, flexible testing will allow clinicians to order one diagnostic panel, while paying for only the targets they suspect, which will provide improved patient care and a higher likelihood for reimbursement.

Who decides what is best for patients?

To enable clinicians to deliver the best patient care possible, the Infectious Diseases Society of America (IDSA) publishes guidelines on infectious disease testing and treatment practices, and serves as the biggest advocate for individual patient needs. The IDSA is composed of thousands of physicians, scientists and public health experts who use empirical data to establish these guidelines, influencing the management and prevention of infectious diseases. Additionally, the IDSA works with federal agencies, Congress and labs across the country to help “protect diagnostic innovation and patient access to care.”2 These guidelines, in conjunction with CMS-issued policies, determine which diagnostic tests and healthcare technologies are considered medically necessary and reasonable, assisting in compliance with reimbursement policies.

Even with the IDSA’s recommendations, healthcare providers still face several challenges when navigating the gray area between providing treatment and ensuring financial solvency. This is especially true when molecular diagnostics are used for gastrointestinal (GI) illnesses. Because of the numerous sources for contracting a GI infection and the similarity of symptoms across multiple illnesses, the diagnostic method for GI infections is often a process of elimination. Although many GI illnesses can resolve without treatment, some pathogens, like Clostridium—or Clostridioides—difficile (C. diff), can lead to serious complications if left untreated. Further, because gastrointestinal diagnostics have historically required multiple testing methods, the clinical need for a customizable assay has become increasingly apparent.

The role of molecular diagnostics in healthcare

In the last decade, clinical microbiology has significantly evolved, and the diagnostic arsenal now includes molecular syndromic panels that can simultaneously detect and identify multiple pathogens associated with bloodstream, gastrointestinal and respiratory infections. These tests have enabled better patient outcomes due to faster turnaround times (TAT) and improved sensitivity,3 which affects everything from the decision to admit a patient to hospital infection control strategies, the recommendation for a specific antibiotic therapy or the avoidance of antibiotics altogether, and how long it takes to get a patient on the most appropriate treatment regimen.

These developments have helped propel a shift away from traditional diagnostic testing methods such as culture or microscopy, because long TAT, low specificity and sensitivity, as well as laborious workflows, tend to increase long-term costs. This is often the case if the first diagnostic test does not yield a positive result and additional testing is required. While syndromic panels can cost more up front than their predecessors, they lead to downstream savings due to a simplified workflow, increased diagnostic yield, improved specificity and a higher likelihood of getting an actionable diagnosis—faster.3 Because of these benefits, molecular syndromic testing is expected to become increasingly common in the coming years.4

Prior to 2016, there were no official policies for how syndromic assays should be used. Since then, policy has evolved to recommend testing based on whether a given test will positively affect patient care. To demonstrate some of the potential circumstances clinicians may face when considering how to test for a suspected case of infectious gastroenteritis, we will discuss three scenarios where a patient’s symptoms and epidemiology drive the choice for testing, as well as the application of flexible testing as a solution to navigate some of these scenarios.

Scenario 1: When a full panel is the right call

There are some cases when reimbursement for a complete panel is clearly justified. For example, an immunocompromised patient who presents with nausea, frequent diarrhea and fever would likely be screened for the entire molecular panel up front, due to an increased clinical need to manage their symptoms as quickly as possible. This testing might include the most common pathogens linked with diarrheal symptoms, such as C. diff, norovirus and Giardia, as well as some of the less common viral, bacterial and parasitic targets.

In this way, reimbursement for diagnostics is linked to the clinical needs of the patient and the likelihood that a positive diagnosis can change the patient’s outcome. However, in general, there has been a shift away from paying for the full panel of testing when a diagnosis won’t necessarily change the course of action for the patient.

Scenario II: Making a run for better diagnostics

A patient who has recently undergone shoulder surgery and was given perioperative antibiotics presents with persistent diarrhea and a fever. According to the 2017 IDSA guidelines, considering the patient’s recent antibiotic treatment, the most likely pathogens responsible for the patient’s symptoms are C. diff or Salmonella. C. diff is known to account for 20-30 percent of antibiotic-associated diarrhea,5 and is the most common cause of infectious diarrhea in healthcare settings.6 Further, some studies have reported that as many as 96 percent of patients with symptomatic C. diff infection had received antibiotics within two weeks before the onset of diarrhea, and all of the patients who had symptoms of C. diff infection had received antibiotics within the last three months.7-9

Because only two pathogens are suspected, a clinician would be forced to either order separate tests for these targets or order a complete molecular panel. In the event that the molecular panel lacked C. diff, this test would also have to be ordered separately. However, this also has the potential for reimbursement challenges. Since reimbursement for the entire panel is not easily justifiable, the patient could be responsible for paying more than they may expect or the clinician could defer to traditional testing methods, which would delay time to therapy up to 92 hours and potentially circumvent critical infection control measures.10 For this patient, a flexible testing solution would enable the doctor to order a test with the suspected targets only, as opposed to a pre-established panel that has more targets than are clinically necessary, at a much higher cost.

Scenario III: A trip to remember

A patient has recently returned from Thailand and presents with a low-grade fever, stomach pain and has had prolonged diarrhea since the last week of their trip. Traveler’s diarrhea is common, with infection rates between 30-70 percent, depending on the destination and the time of year.11 Because of their travel history, this patient may be infected with several different pathogens. In this case, stool testing would be the primary method for detection to narrow down the list.

The prescribing doctor would initially order a screening panel for common causes of traveler’s diarrhea, including E. coli, Salmonella, Campylobacter, Shigella and Vibrio. If the panel came back negative for all the selected pathogens, the doctor would then need to expand the search. For this patient, a flexible testing solution could permit the doctor to simply reveal additional targets instead of having to retest the original specimen, saving valuable time and resources.

Flexible testing - a gateway towards the future

The application of flexible testing in syndromic panels is a recent innovation that is gaining momentum. It was developed to address the clinical need for customizable testing when a patient’s symptoms could be due to several different pathogens. A flexible testing option would enable technicians to perform one assay and then pay to reveal additional results. For example, a physician may order a targeted molecular panel that returns all negative results. Instead of performing an additional test, the physician would request to reveal additional targets on the panel that was already performed, which would be reimbursed, provided a positive result would change the patient’s treatment strategy.

In conclusion

In concert with the latest IDSA guidelines for GI illnesses, flexible testing can help clinicians or physicians navigate the different scenarios that are encountered when screening for infectious diseases, and the examples highlighted here address the need for different levels of diagnostic flexibility. As molecular diagnostics and policies concerning reimbursement for these tests continue to evolve, it will be imperative that the future of healthcare has flexible solutions to navigate the unique needs of every patient. Customizable testing, based on an individual’s symptoms, will lead to improved patient outcomes by reducing time spent re-running tests, decreasing the time to therapy, improving infection control management and increasing operational efficiency at healthcare facilities and diagnostic labs. Faster time to result translates into better patient care, including improved treatment strategies, in a clinically actionable timeframe. Flexible testing synergizes with the latest IDSA GI testing guidelines, as well as current guidance for reimbursement. Because of the potential for downstream savings, it’s likely that tests with flexible target selection will lead to improved long-term clinical, economical and operational benefits for the entire healthcare system. 


  1. Bruen B, Docteur E, Lopert R, et al. The Impact of Reimbursement Policies and Practices on Healthcare Technology Innovation. Office of the Assistant Secretary for Planning and Evaluation. (2016). Executive Summary, pp i. https://aspe.hhs.gov/pdf-report/impact-reimbursement-policies-and-practices-healthcare-technology-innovation
  2. LAB Act Would Correct Diagnostics Reimbursement Cuts. IDSA Newsletters. https://www.idsociety.org/idsa-newsletter/july-24-2019/lab-act-would-correct-diagnostics-reimbursement-cuts/
  3. Hanson K, Couturier M. Multiplexed Molecular Diagnostics for Respiratory, Gastrointestinal and Central Nervous System Infections. Clin Infect Dis. 2016;63(10):1361–1367.
  4. Ramanan P, Bryson A, Binnicker M, et al. Syndromic Panel-Based Testing in Clinical Microbiology. Clin Microbiol Rev. Nov 2017;31(1):e00024-17.
  5. Bartlett J. Antibiotic-associated colitis. Dis Mon. 1984;30:1–54.
  6. Clinical Practice Guidelines for Clostridium difficile Infection in Adults: 2010 Update by the Society for Healthcare Epidemiology for America and the Infectious Diseases Society of America. Infect Control Hosp Epidemiol. 2010;31:5.
  7. McFarland L, Mulligan M, Kwok R, et al. Nosocomial acquisition of Clostridium difficile infection. N Eng J Med. 1989;320:204–210.
  8. Samore M, DeGirolami P, Tlucko A, et al. Clostridium difficile colonization and diarrhea at a tertiary care hospital. Clin Infect Dis. 1994;18:181–187.
  9. Olson M, Shanholtzer C, Lee J Jr, et al. Ten years of prospective Clostridium difficile-associated disease surveillance and treatment at the Minneapolis VA Medical Center, 1982-1991. Infect Control Hosp Epidemiol. 1994;15:371–381.
  10. Tenover F, Baron E, Peterson L, et al. Laboratory Diagnosis of Clostridium difficile Infection. Can Molecular Amplification Methods Move Us Out of Uncertainty? J Mol Diagn. 2011 Nov; 13(6): 573–582. 
  11. Heather CS. Travellers’ diarrhoea. BMJ Clin Evid. 2015; 2015:0901.