Each Additional Hospital Day of Catheterization Increases the Risk of UTI

In 1974, a seminal study found that the number of hospital days spent catheterized is a significant risk factor for urinary tract infection. Catheter-associated urinary tract infections (CAUTIs) remain one of the most common nosocomial infections in the U.S., despite concerted efforts by Medicaid and Medicare to reduce the incidence. Part of the problem is that little is known about risk factors for CAUTI, including the effect of catheter dwell-time.

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Allison S. Letica-Kriegel, MD, resident in the Department of Surgery at Massachusetts General Hospital, and colleagues have conducted the first study in three decades to examine the daily risk of maintaining a urinary catheter. In BMJ Open, they present novel evidence about other risk factors for CAUTI in hospitalized patients.

Cohort

The researchers reviewed electronic medical records of 47,926 patients who received an indwelling urinary catheter (61,047 catheterizations) at an urban academic hospital system between January 1, 2012 and March 31, 2016. The median duration of catheterization was four days.

Incidence of CAUTI

In this population, 861 catheterizations (1.41%) resulted in a CAUTI. The median duration of catheterization was seven days for patients who developed a CAUTI and four days for those who did not. On initial analysis, groups prone to develop a CAUTI were pediatric patients (0 to 17 years old), patients 25 to 64 years old and women.

Kaplan–Meier analysis demonstrated a nonlinear increase in the risk of CAUTI as the duration of catheterization increased. The CAUTI-free rate was 97% at 10 days, 88% at 30 days and 72% at 60 days. This suggests that each extra day of catheterization incrementally increases the risk of CAUTI.

Subgroup Analysis

When Kaplan–Meier analysis was applied to patient subgroups, the researchers identified a significantly higher risk of CAUTI in:

• Pediatric patients vs. adults
• Girls vs. boys (three-fold difference)
• Women vs. men

The researchers then performed a multivariate Cox proportional hazards analysis that controlled for sex, age, patient type (medical vs. surgical) and the presence or absence of the 17 comorbidities included in the Charlson Comorbidity Index. They found additional factors that significantly decreased or increased the risk of CAUTI:

• Stroke: 78% higher risk
• Paraplegia: 40% higher risk
• Congestive heart failure: 25% lower risk

Neurologic units have been shown to have especially high rates of CAUTI, the researchers note, but they were surprised that heart failure lowered the risk. A potential explanation, they say, is that many patients with heart failure are catheterized for diuresis and have their fluid balance monitored closely. That may result in the timely removal of the catheter.

Root Cause Analysis

For 10% of the CAUTIs, clinical teams performed a root cause analysis at the time of infection. The most common contributing factors they identified were comorbidities, lapses in catheter care protocols, active infection, fecal incontinence and duration of catheterization. The duration was considered a contributor in 17% of the cases, but for almost 25% of the cases reviewed, clinicians stated that the catheters could have been removed earlier.

The authors conclude that their results should encourage the use of automated alerts for removal of indwelling urinary catheters. The findings should also guide the timing of those alerts, such as alerting more often for children and adolescents.

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