SAN DIEGO—What physicians report to the Centers for Disease Control and Prevention (CDC) about catheter-associated urinary tract infections (CAUTIs) may differ from they are treating, according to a new study.

In the United States, all hospitals are required to report CAUTIs using the CDC definition. A definition proposed by Infectious Diseases Society of America (IDSA), however, may be more clinically relevant, according to the researchers.

“People in our hospital and in the ICU [intensive care unit] were not feeling that the numbers being reported were nearly as high as what was being treated,” said investigator Paul Pottinger, MD, Associate Professor of Infectious Diseases at the University of Washington School of Medicine in Seattle. “We report according to strict criteria by the CDC, but it is possible that the CDC definition of CAUTIs is too strict or not reflective of the clinical management that physicians are seeing in the ward. We wanted to look at real life experience and see what categories they would fall in.”

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Dr. Pottinger, who presented the study findings at the meeting, said CAUTIs are the most common hospital-acquired infection in the United States, but controversy exists over how to define these infections. He and his colleagues examined the differences between the definitions in the same cohort of patients. Of 2,460 cultures ordered, only 163 (6.6%) met either the CDC or IDSA criteria for CAUTIs.

Dr. Pottinger told Renal & Urology News that this finding was unexpected and suggests that clinicians may be ordering way too many cultures.

The two definitions overlapped in only 46% of cases. The major sources of discordance were the CDC’s limitation to two or fewer cultures and the absence of such a limit in IDSA’s definition. If yeast is the only pathogen that can be cultured, then it is excluded under the IDSA’s definition. The IDSA definition resulted in 45% more cases of CAUTIs compared with CDC’s definition. 

The study suggests that the IDSA definition may be perceived by physicians to be more clinically relevant than the CDC definition, Dr. Pottinger said. The CDC definition is used strictly as a reporting definition, thus what physicians are treating may be significantly different than what is being reported.

“Why is what we track not what we treat?” Dr. Pottinger asked. “Each definition has its flaws and each definition has its strengths. We need to sit down and come to a consensus. There needs to be agreement on one definition for the sake of research purposes and for public reporting.”

For this study, a novel CAUTIs surveillance tool was developed.  It collected electronic medical record data from February 2010 through July 2011, including demographics, diagnoses, catheterization history, body temperature, urinalysis, and urine and blood cultures. The tool was able to capture subjective symptoms found in notes via natural language processing.

The researchers identified 2,460 candidate cases among 1,519 patient admissions. In all of these cases, urine cultures were ordered while the patient was catheterized.  The controls for this study were candidate cases with negative urine cultures. Patients meeting both the CDC’s and IDSA’s definitions of CAUTIs had a hospital and ICU length of stay and mortality rate comparable to controls.