Ventilator-associated pneumonia (VAP) can be overdiagnosed on the basis of positive respiratory cultures in the absence of clinical findings of pneumonia. We determined the perceived diagnostic importance of 6 clinical attributes in ordering a respiratory culture to identify opportunities for diagnostic stewardship.

A discrete choice experiment presented participants with a vignette consisting of the same “stem” plus variations in 6 clinical attributes associated with VAP: chest imaging, oxygenation, sputum, temperature, white blood cell count, and blood pressure. Each attribute had 3–4 levels, resulting in 32 total scenarios. Participants indicated whether they would order a respiratory culture, and if yes, whether they preferred the bronchoalveolar lavage or endotracheal aspirate sample-collection method. We calculated diagnostic utility of attribute levels and relative importance of each attribute.

The survey was administered electronically to critical-care clinicians via a Qualtrics survey at a tertiary-care academic center in the United States.

In total, 59 respondents completed the survey. New radiograph opacity (utility, 1.15; 95% confidence interval [CI], 0.99–1.3), hypotension (utility, 0.88; 95% CI, 0.74–1.03), fever (utility, 0.76; 95% CI, 0.62–0.91) and copious sputum (utility, 0.75; 95% CI, 0.60–0.90) had the greatest perceived diagnostic value that favored ordering a respiratory culture. Radiograph changes (23%) and temperature (20%) had the highest relative importance. New opacity (utility, 0.35; 95% CI, 0.17–0.52) and persistent opacity on radiograph (utility, 0.32; 95% CI, 0.05–0.59) had the greatest value favoring bronchoalveolar lavage over endotracheal aspirate.

Perceived high diagnostic value of fever and hypotension suggest that sepsis vigilance may drive respiratory culturing and play a role in VAP overdiagnosis.

In the absence of pyuria, positive urine cultures are unlikely to represent infection. Conditional urine reflex culture policies have the potential to limit unnecessary urine culturing. We evaluated the impact of this diagnostic stewardship intervention.

We conducted a retrospective, quasi-experimental (nonrandomized) study, with interrupted time series, from August 2013 to January 2018 to examine rates of urine cultures before versus after the policy intervention. We compared 3 intervention sites to 3 control sites in an aggregated series using segmented negative binomial regression.

The study included 6 acute-care hospitals within the Veterans’ Health Administration across the United States.

Adult patients with at least 1 urinalysis ordered during acute-care admission, excluding pregnant patients or those undergoing urological procedures, were included.

At the intervention sites, urine cultures were performed if a preceding urinalysis met prespecified criteria. No such restrictions occurred at the control sites. The primary outcome was the rate of urine cultures performed per 1,000 patient days. The safety outcome was the rate of gram-negative bloodstream infection per 1,000 patient days.

The study included 224,573 urine cultures from 50,901 admissions in 24,759 unique patients. Among the intervention sites, the overall average number of urine cultures performed did not significantly decrease relative to the preintervention period (5.9% decrease; P = 0.8) but did decrease by 21% relative to control sites (P < .01). We detected no significant difference in the rates of gram-negative bloodstream infection among intervention or control sites (P = .49).

Conditional urine reflex culture policies were associated with a decrease in urine culturing without a change in the incidence of gram-negative bloodstream infection.