Study: Stewardship should focus on unnecessary urine cultures vs. antibiotic use

Key takeaways:

• A decline in antibiotics for asymptomatic bacteriuria was linked to a decline in unnecessary urine cultures.
• Researchers said hospitals should prioritize diagnostic stewardship over antibiotic stewardship.

Avoiding unnecessary urine cultures was more effective in reducing antibiotic use in hospitalized patients with asymptomatic bacteriuria than stewardship efforts focused on reducing unnecessary antibiotic treatment, a recent study found.

“Despite national guidelines recommending against treating [asymptomatic bacteriuria (ASB)] in most hospitalized patients, up to 80% are treated with antibiotics,” Valerie M. Vaughn, MD, MSc, SFHM, FACP, an assistant professor of medicine at the University of Utah, and colleagues wrote in JAMA Internal Medicine. “To combat this antibiotic overuse, both diagnostic stewardship (avoiding unnecessary urine cultures) and antibiotic stewardship (avoiding or stopping unnecessary antibiotic use in asymptomatic patients found to have a positive urine culture) have been proposed.”

However, the researchers noted it is not clear which stewardship strategy is more successful because of a lack of large collaborative studies.

To determine which strategy results in better outcomes, Vaughn and colleagues conducted a quality improvement study using data from the Michigan Hospital Medicine Safety Consortium, a statewide collaborative quality initiative involving 50 hospitals.

The study’s primary outcome was overall improvement in ASB-related antibiotic use, measured by the percentage of patients with ASB who were treated with antibiotics.

Data were collected from July 1, 2017, to March 31, 2020, on 14,572 patients with a positive urine culture. Among the cohort, 28.4% had ASB, and 76.8% of that group received antibiotics.

Of the 46 hospitals included in the study, 42 responded to a 2019 follow-up survey. All the responding hospitals had used antibiotic stewardship strategies, and 66.7% of them reported an ASB diagnostic stewardship strategy.

The researchers found that ASB-related antibiotic use decreased over the study period, with the percentage of patients with ASB who were treated for a UTI, dropping from 29.1% (95% CI, 26.2-32.2) to 17.1% (95% CI, 14.3-20.2).

“Compared with baseline, it was estimated that 590 ASB cases were avoided or there were 3,540 fewer unnecessary days of antibiotic therapy,” Vaughn and colleagues noted.

The diagnostic stewardship strategy was associated with a decrease in the percentage of patients with ASB and a positive urine culture, from 34.1% (95% CI, 31-37.3) to 22.5% (95% CI, 19.7-25.6). In contrast, the antibiotic stewardship strategy was associated with a smaller decrease, from 82% (95% CI, 77.7-85.6) to 76.3% (95% CI, 68.5-82.6), and the duration of antibiotics for ASB remained consistent.

The researchers explained that the idea behind diagnostic stewardship “is that a positive test, regardless of the positive predictive value of that result, serves as a powerful nudge for action — in this case antibiotic treatment.”

“Thus, diagnostic stewardship works in part by reducing tests whose results are likely to be false positives,” they wrote.

Ultimately, “even though fewer hospitals reported using a diagnostic stewardship strategy for ASB, it appears to be the more effective strategy,” Vaughn and colleagues concluded.

In a related editorial, Daniel J. Morgan, MD, MS, a professor of epidemiology and medicine at the University of Maryland, Baltimore, and colleagues wrote that a number of diagnostic stewardship interventions are suitable for urine culturing.

“The best interventions include requiring appropriate indications for urine culture ordering and only performing urine cultures if the urine sample has pyuria, indicating inflammation,” they wrote.

Although the study favors diagnostic stewardship over antibiotic steward, Morgan and colleagues wrote that “the effect of these interventions is dependent on the condition being addressed.”

“For instance, diagnostic stewardship appears to have a greater influence on test-based diagnoses like UTI and [Clostridioides] difficile infection, where test positivity is a major driver for treatment decisions,” they wrote. “Antimicrobial stewardship, however, tends to be more effective for infectious syndromes like sepsis and decisions around choice and duration of antimicrobials.”

They concluded that more research is needed “to determine the best use of diagnostic or antimicrobial stewardship for different conditions.”

References:

• Morgan D, et al. JAMA Intern Med. 2023;doi:10.1001/jamainternmed.2023.2756.
• Vaughn V, et al. JAMA Intern Med. 2023;doi:10.1001/jamainternmed.2023.2749.