Urinalysis Overuse in ER Has Repercussions

Urinalysis is overused in the emergency department, with most patients who are tested lacking an appropriate clinical indication, according to a study published in the October issue of JAMA Internal Medicine. This overuse contributes to the overdiagnosis of urinary tract infections and resultantly, excessive use of antibiotics.

While urinalysis has excellent negative predictive value for ruling out a urinary tract infection, a positive result is nonspecific and has been estimated to occur in as many as 90 percent of asymptomatic elderly patients.

The researchers studied 403 consecutive adult patients (median age, 79 years; 52.6 percent women) to assess the appropriateness of urinalysis orders on admission to the general medical service of a large tertiary care center. Assessment took place for four consecutive weeks in September and October 2014, as well as three consecutive weeks in January 2015. Evaluation included assessment of indications for urinalysis (symptoms of urinary tract infection or acute kidney injury), as well as the frequency of empirical therapy for urinary tract infection, orders for urine culture, and antimicrobial prescriptions based on urine culture results.

In total, roughly six in ten patients (62.0 percent) underwent urinalysis at the time of admission at the discretion of either the emergency department or general medicine physicians. Of these 250 patients tested, the vast majority (79.2 percent) lacked symptoms of either urinary tract infection or acute kidney injury. Only the presence of multiple comorbidities was significantly associated with urinalysis orders without a clinical indication.

As might be expected, positive urinalysis results were significantly associated with increased likelihood of urine culture orders, as well as antibiotic prescription among asymptomatic patients. In symptomatic patients, the researchers say that “appropriate urinalysis orders” were used “effectively” to exclude urinary tract infections and withhold unnecessary antimicrobial therapy.

“These findings highlight the harms of urinalysis overuse in this patient population because positive urinalysis results can introduce cognitive biases in favor of a urinary tract infection diagnosis even when patients lack accepted guideline-based criteria,” write the authors led by Penny Yin, M.D., from University of Toronto in Canada. “Limiting indiscriminate urinalysis ordering has the potential to improve urine culture and antimicrobial prescribing practices among general medicine patients.”