Routine urinary tract infection tests are among the most commonly ordered lab tests in hospitals, and their excessive utilization raises the risk of unnecessary antibiotic prescriptions and additional healthcare costs. A study conducted by researchers at Washington University School of Medicine in St. Louis demonstrated how a simple reflex algorithm in the computerized physician ordering system (CPOE) managed to cut inpatient urine cultures in half without compromising patient care.

“Overutilization of urine culture in isolation is problematic and may drive treatment of asymptomatic bacteriuria, which is common in diabetic patients, the elderly, and in people with indwelling urinary catheters,” study coauthor Melanie L. Yarbrough, PhD, assistant professor, pathology and immunology, told CLN Stat. Once a positive urine culture result is reported, it’s difficult to ignore and often leads to inappropriate treatment. “In addition, unnecessary urine culturing wastes the time and resources of clinical microbiology laboratories, which are increasingly faced with a shortage of skilled laboratory personnel,” Yarbrough said. Many clinicians don’t know how to interpret results or aren’t familiar with a recommendation by infectious disease specialists to order a urine dipstick test first to detect signs of bladder infection.

The study took place over a 6-month period at Barnes-Jewish Hospital and included hospitalized adults who had at least one urine culture taken during their stay. The researchers launched a series of interventions to guide more prudent use of urine tests in patients. Clinicians initially received an email that discussed the rationale for ordering a dipstick test prior to culture. The laboratory worked within the hospital information system to implement an algorithmic testing approach for urine culture. “In the algorithm, the urine culture order was precipitated on the basis of a positive urinalysis, as urine that is positive for markers of inflammation are indicative of infection,” Yarbrough said. Researchers then changed the CPOE system to default to a dipstick test instead of a culture test by itself.

Clinicians who bypassed the default and ordered a culture test first had to open an additional screen on their computers to do so.

The laboratory also changed its urine collection system, adding a boric acid tube to preserve urine stability for bacterial culture. “This was critical, as urine specimens were held for some time in the laboratory while urinalysis testing was being performed,” Yarbrough noted.

Comparing all urine culture tests ordered 15 months prior to the intervention and 15 months afterward, researchers determined that it led to 45% fewer urine cultures, dropping from 38 orders per 1,000 patient days before the intervention to 21 orders afterward. While the number of urine cultures from patients with catheters—those at high risk for UTIs—decreased from 7.8 to 1.9 per 1,000 patient days, there was no change in the number of catheter-associated UTIs. “We also noticed a 16.4% increase in the proportion of positive urine cultures and a 6.9% decrease in the proportion of isolated urine cultures obtained,” the researchers reported.

Overall, Yarbrough and her colleagues estimated that the intervention saved $103,845 in laboratory costs, given that a urine culture costs about $15 to perform.

“Laboratories interested in this type of approach should look at their testing volumes, including how often urine cultures are ordered in isolation, without corresponding urinalysis, to determine the scope of the problem at their local institution,” Yarbrough suggested.

“If reflex testing is implemented, consideration should be given on test naming and how it will appear in the ordering system. Keep it simple and clear, and ask physicians for input!”