By Emily Hayes, LabPulse.com editor in chief

August 28, 2019 -- Urine testing is resulting in the inappropriate treatment of asymptomatic bacteriuria (ASB) with antibiotics and longer hospital stays, according to a study funded by Blue Cross Blue Shield of Michigan and published online August 26 in JAMA Internal Medicine.

For the study, researchers retrospectively evaluated the records of 2,733 hospitalized patients with asymptomatic bacteriuria in 46 Michigan hospitals. They examined how many patients received antibiotics after an abnormal urinalysis result, along with a range of clinical outcomes, including mortality, readmission rates, and emergency room visits. The group also looked at how long patients were hospitalized after a urine test.

Of the 2,733 patients, 82.7% were treated with antibiotics (the median time of treatment was seven days), and this was associated with longer hospital stays after urine testing -- a median of four days versus three days. While patients were often treated with antibiotics and stayed in the hospital longer, they did not have better clinical outcomes.

Asymptomatic bacteriuria is often misdiagnosed as a urinary tract infection (UTI), and it should not be treated with antibiotics in most cases, the authors noted.

"Given that UTI is one of the most commonly treated and misdiagnosed conditions in [U.S.] hospitals, a 1-day difference in length of stay would have a substantial effect on hospitalization-related costs," wrote Dr. Lindsay Petty, an infectious disease specialist at the University of Michigan, and colleagues.

Factors that increased the likelihood of an antibiotic prescription included older age, dementia, and an abnormal urine test, which was typically done on the first day of hospitalization.

"To possibly reduce inappropriate antibiotic use, stewardship efforts should focus on improving urine testing practices and management strategies for elderly patients with altered mental status," the authors wrote.

Out of step with guidelines

The review was undertaken to quantify inappropriate treatment in a tricky area of medicine. Blue Cross Blue Shield of Michigan provided funding for the study but was not involved in conducting it, though several authors reported that they had received grants from the insurance company.

"Despite national guidelines recommending against antibiotic therapy for ASB, high treatment rates persist," Petty and colleagues wrote. "Inappropriate use of antibiotics can result in adverse events, increased antibiotic resistance, and Clostridioides difficile infection ... prompting hospitals and antimicrobial stewardship programs to adopt strategies to reduce inappropriate antibiotic use, in particular, ASB treatment."

The authors noted that doctors may go against guidelines out of concern for adverse outcomes due to treatment not being administered. The study included a diverse mix of hospitals where records of outcomes were available.

Patients were deemed to be asymptomatic if they had none of the following:

  • Dysuria
  • Urinary frequency/urgency
  • Suprapubic pain
  • Fever
  • Costovertebral pain/tenderness
  • Hematuria
  • Autonomic dysreflexia or increased spasticity in patients with spinal cord injury

The researchers stressed that antibiotic treatment did not appear to benefit patients in terms of mortality, hospital readmissions, emergency room visits, and other outcomes.

"These findings support guideline recommendations against ASB treatment among hospitalized patients and suggest potential harm associated with treatment," they wrote.

Petty and colleagues suggested that too much testing and treatment are being done. Educational efforts are needed to raise awareness of the poor positive predictive value of urinalysis and to steer providers away from urine testing in patients who do not have symptoms, they advised.

"Despite common misperceptions, positive urinalysis or [urine culture] results do not define a UTI or necessitate antibiotic therapy," they wrote. "A negative urinalysis result makes a UTI unlikely, but a positive urinalysis does not diagnose infection given its poor positive predictive value. However, abnormal urinalysis was the top indication documented for [urine culture] and the strongest factor associated with treatment."

The results add to the evidence for a "less-is-more approach, especially in elderly patients," and computerized decision support may be helpful in decreasing the rate of urine testing in asymptomatic patients, they noted.


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