April 14, 2019
4 min read

Q&A: The evolution of CAUTI and need for better metrics

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Sonali Advani, MBBS, MPH
Sonali Advani

Current metrics used to monitor progress in the prevention of catheter-associated UTIs, or CAUTIs, may underestimate infectious and noninfectious catheter harm and may need to be updated, experts argued recently.

Writing in Infection Control & Hospital Epidemiology, Sonali Advani, MBBS, MPH, assistant professor of medicine (infectious diseases) at the Yale School of Medicine and associate hospital epidemiologist at Yale-New Haven Hospital, and Mohamad G. Fakih, MD, MPH, senior medical director of the Center of Excellence for Antimicrobial Stewardship and Infection Prevention at Ascension Health, suggested it is time for more inclusive performance metrics to measure catheter harm.

According to Advani and Fakih, approximately 15% to 25% of patients in the acute-care setting are exposed to a urinary catheter, placing them at risk for infectious and noninfectious complications. The national focus has been on CAUTI prevention but the current metrics may not adequately capture overall catheter harm, Advani and Fakih noted.

Infectious Disease News spoke with Advani about CAUTI prevention progress, CAUTI surveillance and what more inclusive metrics would look like. – by Marley Ghizzone

Why is it important how HAIs like CAUTIs are measured?

HAIs have a significant impact on patient safety and health outcomes worldwide. Rates of these HAIs reflect the quality of care received in health care settings to government agencies and patients. The metrics used for measuring these HAIs impact CMS reimbursements and influence quality improvement efforts. The prevention of CAUTI has been an integral component of the national efforts to reduce HAIs. To monitor progress in CAUTI prevention, the National Healthcare Safety Network (NHSN) CAUTI metric was adopted nationally as the outcome measure. Since inclusion of the NHSN CAUTI metric in the Hospital-Acquired Condition Reduction Program, our national focus has been on preventing NHSN CAUTI events.

Why is it difficult to measure patient harm from CAUTIs?

There is no single perfect metric to evaluate patient harm from a urinary catheter because of challenges with defining elements of a CAUTI clinically. The NHSN CAUTI metric has been refined over the past few decades to align with a clinical definition for symptomatic CAUTI. However, this definition relies on the presence of a positive urine culture and fever as integral criteria. Hence, NHSN CAUTI events are more susceptible to changes in urine testing practices and the prevalence of fever.

Additionally, our current metrics measure rates of NHSN CAUTI events rather than capturing catheter-related harm. Noninfectious catheter complications, such as urethral injury, pain or inadvertent catheter removal, have received limited attention.


What are the current metrics for measuring CAUTIs , and what are their limitations?

The NHSN Standardized Infection Ratio (SIR), which is the ratio of observed to predicted NHSN CAUTI events, is the nationally used metric to compare an institution’s performance to the national benchmark from a baseline period. However, this metric may not adequately capture the impact of quality improvement efforts in all scenarios. The SIR does not adjust for local factors related to overuse of catheters (thus potentially showing a lower risk per catheter day) or unit-specific interventions. Hence, these metrics risk shifting the emphasis from a process focused on decreasing catheter use to frequency of testing. Additionally, our surveillance methods involve cumbersome chart reviews and subjective definitions, which are prone to error and bias.

In our recent article, we review the most commonly implemented strategies for CAUTI prevention and some of their unintended consequences due to the limitations of current metrics. For example, external collection devices (ECDs) are becoming increasingly popular as alternatives to indwelling catheters. However, patients using ECDs are still susceptible to nosocomial UTIs and local adverse effects, even if these devices eliminate NHSN CAUTI events.

How should the metrics be refined?

Ideally, performance metrics should reflect infectious and noninfectious complications and align with quality improvement efforts. With our current metrics, decreasing catheter use may not lower NHSN CAUTI rates or the SIR in all settings because it may select for higher risk group of catheters, while decreasing the denominator (catheter days). We suggest more inclusive metrics like the Standardized Device Utilization Ratio (SUR), catheter-associated bacteriuria and a population-based metric called population SIR.

Population SIR accounts for the risk for device exposure and infection to all patients, and combines elements of SIR and SUR. It is calculated as the ratio of observed to predicted NHSN-CAUTI events based on the predicted device days for the population (compared with our current SIR, which is based on actual device days). This metric will entice teams to also focus on noninfectious complications because it rewards hospitals that focus on device utilization.

How would better CAUTI metrics support antimicrobial stewardship?

Hospitals are currently incentivized to concentrate their efforts on decreasing NHSN CAUTI events, rather than focusing on catheter harm or overtreatment of bacteriuria. In our review, we propose three key metrics to measure overall catheter harm and support stewardship efforts: SUR, catheter-associated bacteriuria and population SIR.


The SUR adjusts for hospital- and unit-level factors and may be used as a surrogate for potential catheter harm.

Catheter-associated bacteriuria (asymptomatic and symptomatic) is more common than CAUTIs and is a key driver of inappropriate antibiotic use. Positive urine cultures prompt antimicrobial therapy, even in the absence of symptoms.

Population SIR, described earlier, accounts for risk of CAUTI and device use over time.

We recommend evolving to metrics that align with our interventions and provide meaningful information back to facilities to improve outcomes. Metrics like SUR, catheter-associated bacteriuria and population SIR can motivate decision-makers to prioritize resources toward decreasing overall device harm. This will also give us the opportunity to educate providers regarding appropriate device use and antimicrobial stewardship.


Advani SD, Fakih MG. Infect Control Hosp Epidemiol. 2019;doi:10.1017/ice.2019.43.

Disclosures: Advani and Fakih reports no relevant financial disclosures.