Incidence of Catheter-Associated and Non-Catheter-Associated Urinary Tract Infections in a Healthcare System

The Centers for Disease Control and Prevention (CDC) has estimated that each year in the United States, 1.7 million infections that occur in hospitals result in 99,000 deaths. Of these infections, urinary tract infection (UTI) is the most common, accounting for 32% of all healthcare-associated infections and resulting in a total cost in the United States of $390-450 million (in 2007 dollars). The major risk factor for UTI is an indwelling urinary catheter. For this reason, surveillance efforts by the National Nosocomial Infections Surveillance System (NNIS) and, more recently, the National Healthcare Safety Network (NHSN) have focused on urinary catheter-associated urinary tract infection (CAUTI) in the intensive care unit (ICU). In addition, recent authoritative guidelines for the prevention of UTI have also focused on CAUTI. The mean incidence rate of CAUTI (per 1,000 catheterdays) in patients in the ICU has been reported to range from 3.1 to 7.4. " Only limited data are available regarding the incidence of CAUTI outside of the ICU. Because NHSN does not publish data regarding the incidence of non-catheterassociated UTI, the current incidence rate of this infection is not available. For these reasons, we undertook this study to evaluate the incidence of both catheter-associated and noncatheter-associated UTI stratified by medical service and type of unit in a university hospital. This study was conducted at the University of North Carolina (UNC) Hospitals. Laboratory-based comprehensive hospital-wide surveillance has been conducted using definitions required for reporting to NHSN by 6 infection preventionists. Urinary catheter-associated infections were tracked quarterly in all patients cared for by UNC home health or hospice using modified NHSN definitions until July 2008, when we applied APIC/HICPAC definitions. Patients with asymptomatic bacteriuria were not included in the database as having healthcare-associated UTI. All data are entered into a computerized database. Infections are ascribed to both a hospital location (eg, ICU, ward) and a medical service (eg, medicine). Locationand service-specific rates for CAUTI were calculated as infections per 1,000 urinary catheter-days, and rates for non-catheter-associated UTI were calculated as infections per 1,000 patient-days at risk (total catheter-days subtracted from total patient-days). Confidence intervals were calculated using the mid-P exact method. This study was approved by the Institutional Review Board of UNC at Chapel Hill. UNC hospital patients had 1,453 healthcare-associated symptomatic UTIs, of which 1,068 (72.2%) were CAUTI and 411 (27.8%) were non-catheter-associated UTI from 2006 through 2009 (Table 1). Overall, 45.2% of CAUTI occurred among ICU patients, while only 22.3% of non-catheterassociated UTI occurred among ICU patients. The rates of CAUTI were higher in the surgery and pediatric services compared to the medicine service. However, the rates of CAUTI did not differ markedly between patients in an ICU versus a non-ICU setting. For almost all hospital locations and services, the rate of CAUTI was significantly higher than the rate of non-catheter-associated UTI, based on nonoverlapping 95% confidence intervals. The only exception was in the medicine ICU, where the number of UTIs and patient-days at risk were both low, resulting in a wide confidence interval that was nonoverlapping with the CAUTI rate. The service with the highest combined rate of both CAUTI and non-