Home Infectious Disease “Diagnostic stewardship” prevents unneeded antibiotic prescribing

“Diagnostic stewardship” prevents unneeded antibiotic prescribing

You may not know the term but it's a key practice to safeguard antibiotics

January 2023

“DIAGNOSTIC STEWARDSHIP” may be a term that many hospitalists aren’t familiar with. But according to Valerie Vaughn, MD, MSc, director of hospital medicine research at the University of Utah in Salt Lake City, this type of stewardship is something hospitalists do all the time.

“They may call it evidence-based medicine or high-value care or Choosing Wisely,” says Dr. Vaughn. But every time physicians decide that their patients’ diagnosis based on their symptoms—or the lack thereof— doesn’t warrant ordering more labs or imaging, that’s diagnostic stewardship. “Front-line providers are always practicing diagnostic stewardship. They’re just calling it something different.”

Dr. Vaughn is the hospitalist lead of the antimicrobial use initiative for the Michigan Hospital Medicine Safety Consortium, a research collaborative among Michigan hospitals funded through that state’s Blue Cross Blue Shield. For many years, she and her colleagues at the University of Michigan—where she remains an adjunct professor—have worked with the collaborative to research ways to prevent inappropriate antibiotic prescribing, reduce the use of broad-spectrum antibiotics and lower the duration of antibiotic therapies when those are needed.

“Diagnostic stewardship strategies win the day over antibiotic stewardship, at least when it comes to ASB.”

~ Valerie Vaughn, MD MSc University of Utah


In their latest study, Dr. Vaughn and her team worked with several dozen Michigan hospitals to try to prevent treatment of asymptomatic bacteriuria (ASB). Despite national guidelines that universally recommend against treating ASB, up to 80% of these patients receive antibiotics when hospitalized, driving up costs and antimicrobial resistance.

For years, Dr. Vaughn points out, she and her colleagues have preached antibiotic stewardship, trying to convince clinicians to not prescribe antibiotics when urine cultures come back positive for patients who have no UTI symptoms.

“We have been beating the drum over and over again, ‘Stop treating that positive test!’ ” she says. “But we haven’t made much progress.”

In this latest study, she and her research team found that a different set of strategies might work. Some hospitals for the study decided to instead intervene earlier in the ordering process to see if they could prevent doctors from ordering a urine culture in the first place. That eliminates the possibility that a culture will come back positive in a patient with ASB—which is always a problem, says Dr. Vaughn, because doctors tend to knee-jerk treat any positive lab.

When the University
 of Michigan first embarked on their antibiotic stewardship program, they scoured a week of data from their own hospital charts. The goal was to get an idea of how well physicians were documenting their antibiotic orders. See Prescribing too many antibiotics?

The goal of the research, in other words, was to encourage clinicians in participating hospitals to order urine cultures for only those patients who have UTI symptoms, and that is diagnostic stewardship in action. In results that Dr. Vaughn presented at the IDWeek conference in October 2022, the research found that the percentage of patients across those hospitals treated for a UTI who actually had ASB fell by about one-third.

“I believe,” says Dr. Vaughn, “that ours is the first study to demonstrate this take-home point: Diagnostic stewardship strategies win the day over antibiotic stewardship, at least when it comes to ASB.”

Automatic orders are a big problem
Forty-six Michigan hospitals participated in the study from July 2017 through March 2020. Over that time, more than 14,500 patients were found to have positive urine cultures; 28% had asymptomatic bacteriuria, while 72% had a UTI. (Among the ASB group, a whopping 77% received antibiotics.) In addition to seeing a drop in the percentage of patients treated for a UTI who actually had ASB, researchers also saw a significant decrease in the percentage of urine cultures being collected for patients with ASB.

One of the safety consortium’s biggest roles is sharing best practices and evidence with hospital participants. As Dr. Vaughn points out, evidence backs at least 20 different diagnostic stewardship strategies, which the consortium recommended that member hospitals consider pursuing. Which of those strategies made sense for any given program, she explains, depends on the hospital.

Many diagnostic stewardship strategies have to do with what Dr. Vaughn calls “order set hygiene.” In many order sets—for admission, the ED, delirium or preop— ordering a urine culture is already prechecked. “People may be surprised at where these things hide,” she points out. “We recommend that hospitals do a root-cause analysis and, where urine cultures are automatically part of order sets, get rid of them.”

Such prechecked cultures “probably drive a lot of antibiotic overuse,” she adds. “But not all hospitals include a urine culture in such sets.” In those cases, diagnostic stewardship may need to target a particular department or group of clinicians.

Say a hospital discovers that many orders for urine cultures originate in the ED. “Maybe the guidelines the ED nurses are following need to be changed,” Dr. Vaughn says. “Or maybe you need a two-step process where a nurse sends a culture, but a physician has to actually put the order in before that culture is run. The goal is to reduce the number of unnecessary urine cultures being performed.”

Behavioral nudges can help
Hospitals are also encouraged to operationalize diagnostic stewardship in their EHRs. “The pop-up alerts that annoy everyone when ordering are still somewhat effective,” says Dr. Vaughn. “Such an alert would point out that doctors should order urine cultures only in patients with UTI symptoms.”

Another approach is changing how orders are listed in the EHR, with urinalysis listed first and urine culture second. “People are more likely to choose the first option you give them,” she says. “There are a bunch of different behavioral techniques—or nudges—like that you can use.”

Dr. Vaughn also notes that diagnostic and antibiotic stewardship approaches aren’t mutually exclusive or even separate interventions.

“They often overlap in bundled interventions,” she says, “and sometimes the teams working on each are the same people.” The most common antibiotic stewardship strategy, she adds, is audit and feedback. Clinicians—or departments—get data on which antibiotics they’re ordering, how often they are prescribing antibiotics when they shouldn’t and whether antibiotic regimens should be shorter.

Both sets of strategies, she says, will be increasingly needed. “We’re getting more and more multicomponent PCR tests that have panels for 20 different items, and we have no idea what to do with all those results when we get them,” Dr. Vaughn says. “We need to consider the downstream effects of even ordering those tests, and that will become only more important in the future.”

Phyllis Maguire is Executive Editor of Today’s Hospitalist.

Reflex testing? You may want to reconsider

In its research with hospitals throughout Michigan, the powerhouse Michigan Hospital Medicine Safety Consortium relies on three broad areas to incentivize quality improvement. Valerie Vaughn, MD, MSc, the hospitalist lead of the antimicrobial use initiative for the consortium, explains that the first pillar of incentives is data-sharing with benchmarking.

“Hospitals can see their performance compared to other facilities and identify high-target areas for improvement,” she points out. “When you see that your hospital is doing worse on a certain metric that dozens of others, that’s very powerful and it helps with buy-in.”

The consortium also shares best practices through collaborative-wide meetings held three times a year. And participating hospitals are also eligible for pay-for-performance incentives, one metric of which is now tied to asymptomatic bacteriuria treatment rates. “The pay-for-performance incentive is quite modest, although money often gets the interest of hospital leadership,” Dr. Vaughn says. “Of all these strategies, I think the data-sharing is the most effective.”

One thing the consortium usually doesn’t do, however, is try to steer participating hospitals clear of strategies they may want to try. But that is changing, Dr. Vaughn says, when it comes to urinalysis with reflex testing.

As she explains, doctors in some hospitals order a urine culture at the same time as a urinalysis (another practice the consortium doesn’t recommend). But one approach becoming more common is to order a urinalysis with a reflex test.

“A reflex test is getting a urine culture only if the urinalysis meets thresholds for a certain amount of bacteria,” she says. “The problem is that, while urinalysis has great negative predictive value, it tells you nothing if it’s positive about whether the patient has a UTI or asymptomatic bacteriuria. So reflex testing doesn’t reduce the number of false positives”—and false positives too often lead to antibiotic treatment.

As a result, says Dr. Vaughn, “we’re now starting to recommend that hospitals reconsider doing reflex testing. That’s not one practice I recommend that people do.”

Published in the January/February 2023 issue of Today’s Hospitalist

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