Key Takeaways:
- Automation has not enhanced the accuracy of UTI screening tests, according to research.
- Relying on the absence of pyuria to avoid urine cultures could result in untreated UTIs in children.
- Automated screening missed 1 in 5 febrile infants and toddlers with UTIs due to the lack of pyuria, a study published in Pediatrics found.
Study Overview:
As automated dipstick and urinalysis tests become more common, Dr. Nader Shaikh, MD, MPH, a professor at the University of Pittsburgh School of Medicine, and colleagues set out to investigate whether automation improved the accuracy of UTI screenings.
The study focused on pyuria, as the now-retired 2011 American Academy of Pediatrics (AAP) guidelines required a positive pyuria test result to diagnose a UTI. This led many medical centers to order urine cultures only for children showing signs of pyuria. However, subsequent research indicated that this approach may have left many children with untreated UTIs, which contributed to the AAP retiring these guidelines in 2021.
In response, new WikiGuidelines released in November recommended against using urinalysis alone to decide whether a urine culture is needed.
Methods:
The study analyzed data from 4,188 children aged 1 to 35 months (72% girls, mean age 12.2 months) who underwent catheterization for suspected UTIs between June 2019 and April 2023. Researchers evaluated the sensitivity and specificity of five different testing methods, including automated white blood cell (WBC) enumeration and digital imaging with particle recognition.
Out of the 4,188 children, 3,377 (81%) had a fever, and 407 (9.7%) tested positive for a UTI. The study found that the sensitivity of the tests varied:
- Leukocyte esterase on a dipstick: 81%
- White blood cell count with a microscope: 82%
- Automated WBC enumeration with flow cytometry: 88%
- Digital imaging with particle recognition: 76%
The combination of pyuria and bacteriuria showed a higher sensitivity (over 90% for most modalities), but the specificity was too low in many cases, the researchers noted. They also found that pyuria was less common in infections caused by pathogens other than Escherichia coli.
Key Findings:
- One in five febrile children with positive urine cultures did not have pyuria.
- Digital imaging with particle recognition, the most commonly available automated modality, missed 35% of febrile children with positive urine cultures.
- The study concluded that automation has not improved the accuracy of UTI screening tests. The practice of relying on pyuria to trigger cultures is prone to missing children who may have a positive culture result.
Conclusion:
The study emphasizes that automation in UTI screening has not led to more accurate tests and that decisions based solely on the absence of pyuria may overlook children with UTIs.
