Impact of diagnostic stewardship on catheter-associated urinary tract infections and patient outcomes.

Background: Diagnostic stewardship of urine cultures from patients with indwelling urinary catheters may improve diagnostic specificity and clinical relevance of the test, but risk of patient harm is uncertain.

Methods: We retrospectively evaluated the impact of a computerized clinical decision support tool to promote institutional appropriateness criteria (neutropenia, kidney transplant, recent urologic surgery, or radiologic evidence of urinary tract obstruction) for urine cultures from patients with an indwelling urinary catheter. The primary outcome was a change in catheter-associated urinary tract infection (CAUTI) rate from baseline (34 mo) to intervention period (30 mo, including a 2-mo wash-in period). We analyzed patient-level outcomes and adverse events.

Results: Adjusted CAUTI rate decreased from 1.203 to 0.75 per 1,000 catheter-days (P = 0.52). Of 598 patients triggering decision support, 284 (47.5%) urine cultures were collected in agreement with institutional criteria and 314 (52.5%) were averted. Of 314 patients whose urine cultures were averted, 2 had a subsequent urine culture within 7 days that resulted in a change in antimicrobial therapy and 2 had diagnosis of bacteremia with suspected urinary source, but there were no delays in effective treatment.

Conclusion: A diagnostic stewardship intervention was associated with an approximately 50% decrease in urine culture testing for inpatients with a urinary catheter. However, the overall CAUTI rate did not decrease significantly. Adverse outcomes were rare and minor among patients who had a urine culture averted. Diagnostic stewardship may be safe and effective as part of a multimodal program to reduce unnecessary urine cultures among patients with indwelling urinary catheters.