On the heels of the antibiotic stewardship movement, there is a new push to rein in and refine the use of diagnostics to detect healthcare-associated infections (HAIs).

As with antibiotics, the call for diagnostic stewardship began due to the current perception that too much testing is being done, resulting in false positives and unnecessary treatments that may harm patients.

“In the majority of studies across medicine in the U.S., there is a significant amount of overtesting that occurs across disciplines,” says Costi D. Sifri, MD, hospital epidemiologist at the University of Virginia Health System in Charlottesville. “The infectious disease world may be coming to this a little bit later than other disciplines, but this is well recognized and understood in things like radiology and laboratory testing for hospitalized patients.”

Sifri and colleagues report¹ that “most current efforts to reduce HAIs focus on strategies to prevent infection without addressing unnecessary testing or diagnostic error.”

“Overuse of tests is predicted to increase false positives that trigger needless downstream cost and treatment that may cause harm for the patient,” they report. “Conversely, test underuse risks missed diagnoses and potential harm related to untreated conditions. As with antimicrobial utilization, we hypothesize that there exists a state of optimal test use for HAIs in at-risk patients.”

Accordingly, diagnostic stewardship for HAIs begins with an attempt to identify this “sweet spot,” he says.

“We emphasize this idea of a ‘Goldilocks’ area of proper testing,” he says. “There is a significant amount of overtesting, but there could be risks if we swing the pendulum too far and go to undertesting. That hasn’t yet been identified as a true problem, but we anticipate that it could be.”

The concept is analogous to antibiotic stewardship, where the goal is to refine administration rather than eliminate drug use.

“You want to use the right antibiotic of the most narrow spectrum for the duration of time that leads to the best outcome for the patient without relapse, but also without unnecessary exposures to antibiotics,” Sifri says. “Yet, if we limit antibiotics too much, we could have bad outcomes for patients.”

This recognition is translating to greater attention to both the frequency of blood and urine cultures and the techniques and diagnostics used. Honing testing could also prevent infections by blocking unnecessary antibiotic administration, avoiding, for example, the well-established risk of patients on broad-spectrum drugs to develop C. diff.

“The whole of diagnostic stewardship is sort of this articulation of proper tests collection, the right type of tests, and then the right interpretation,” he says. “That is the new paradigm.”

Included in New Guidance

One of the first guidelines to address the concept of diagnostic stewardship was recently published in the form of C. diff recommendations by several infectious disease groups and the Centers for Disease Control and Prevention.² These guidelines, for example, recommend testing patients for C. diff with new onset of unexplained diarrhea, defined as three or more unformed stools in 24 hours. The guidelines also noted that molecular tests are used in more than 70% of hospital labs, but these tests have pros and cons. For example, nucleic acid amplification testing for C. diff toxins “may identify colonized rather than clinically infected patients.”

“It is the first guideline I’m aware of where there are different recommendations depending on whether you have diagnostic stewardship as part of your intervention,” Sifri says.

Similar to their critical supporting role in antibiotic stewardship, infection preventionists can be key players on diagnostic teams. There is a need for insight from IPs “on decisions of not only how to test patients, but whom to test,” he says. “Their knowledge and understanding of healthcare infections can help people working in the clinical laboratory.”

For example, IPs may emphasize to clinical laboratorians when rapid diagnostics are particularly helpful in terms of patient identification.

“A rapid test to identify C. diff, for example, may be of high value to an infection preventionist so they can make a decision on whether the patient needs to continue to be in isolation,” he says.

Likewise, the timing and accuracy of diagnostics can inform the type of hand hygiene or the intensity of environmental cleaning needed.

“The IP can guide the decision of whom to test through tools that I think we are just starting to understand, like clinical computer decision-support tools or algorithms that can be implemented on hospital floors,” Sifri says. “They know how to disseminate that information to bedside providers, and that will be to the benefit of everyone.”

In addition, in the era of value-based purchasing and other quality metrics, the Centers for Medicare & Medicaid Services (CMS) may eventually incentivize diagnostic stewardship, he notes. This could include quality improvement process measures like staff education on test ordering, interpretation, and proper specimen collection.

“In the near future, the CMS may begin to require diagnostic stewardship in the form of an approved clinical-decision support system to receive full payment for advanced diagnostic imaging tests,” Sifri and colleagues note in the paper.

While such incentives can drive quality improvement, there also is a more insidious aspect where testing decisions are influenced beyond the clinical realm.

Overtesting has long been termed “defensive medicine.” There also are anecdotal reports of not wanting to obtain a blood culture “because you don’t want to be blamed for a central line infection,” he says.

“That’s the kind of thing ID clinicians are hearing and are concerned about,” he says. “There may be changes in testing approaches because some of these hospital-acquired conditions may have significant consequences.”

Testing for HAIs also raises compelling medical and ethical questions because the results may not only protect the immediate patient, but others downstream that could be exposed. The stakes are higher.

“The consequences of being wrong have potential impact beyond the patient you are caring for,” Sifri says. “That is unique and different from, for example, a mammogram or routine testing for hospitalized patients. It is different if you have a delayed diagnosis for C. diff or MRSA.”

REFERENCES

1. Madden GR., Weinstein RA, Sifri CD. Diagnostic Stewardship for Healthcare-Associated Infections: Opportunities and Challenges to Safely Reduce Test Use. Infection Control & Hospital Epidemiology, 2018;39;2:214-218.
2. McDonald LC, Gerding DN, Johnson S, et al. Clinical practice guidelines for Clostridium difficile infection in adults and children: 2017 update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA) [Published online February 15, 2018]. Clin Infect Dis doi: 10.1093/cid/cix1085.