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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

The risk of urinary infection appears low with very short-term use but increases with the time that a patient has a catheter. Women and patients with paraplegia or cerebrovascular disease are at increased risk.

This US-based retrospective analysis of electronic health records identified 148,361 indwelling catheterisations, of which 61,047 were for three or more days, in five hospitals - two university hospitals, two community and one children’s hospital - where the median duration of catheterisation was four days.

The overall infection rate was 1.64 infections per 1,000 catheter days, and about 2.7% of patients developed an infection if the catheter was in place at ten days. Reviewing their need for catheterisation is important where possible.

Why was this study needed?

Urinary catheters are used to drain the bladder of a person who has difficulty urinating naturally or is prevented from doing so by their illness or treatment. Indwelling urinary catheters comprise a flexible tube inserted into the bladder, held in place by an inflated balloon in the bladder. Occasionally catheters are removed immediately, but that was not the case in this study.

Catheter use is linked with a large proportion of UK healthcare-associated urinary tract infections and accounts for approximately 75% of US hospital-acquired urinary tract infections.

Urinary tract infections can affect the bladder (cystitis), urethra (urethritis) or kidneys. NHS England leads a national programme to reduce the number of catheter-associated urinary tract infections.

What did this study do?

A retrospective review of indwelling catheterisations in two large academic medical centres, two community hospitals and a paediatric hospital was carried out between 1 January 2012 and 31 March 2016. Time of catheter use was recorded in the electronic nursing record flowsheet. If multiple catheterisations occurred in a single indwelling urinary catheter episode, only the first catheterisation was recorded. Nearly 140,000 catheterisations were recorded altogether.

The 61,047 catheterisations of more than three days were highlighted because this is a criterion for the diagnosis of catheter-associated urinary tract infection, according to the US Centers for Disease Control and Prevention definition.

Assessments of infection-free survival rates were reported for paediatric compared with adult patients and female compared with male patients. The analysis included time to infection and presence or absence of 17 comorbidities.

What did it find?

  • Catheter-associated urinary tract infection rates increased with each additional day of catheterisation. Catheter-associated urinary tract infection-free survival was 97.3% (95% confidence interval [CI] 97.1% to 97.6%) at 10 days, 88.2% (95% CI 86.9% to 89.5%) at 30 days and 71.8% (95% CI 66.3% to 77.8%) at 60 days.
  • Children and adolescents (0 to 17 years) had a catheter-associated urinary tract infection rate of 2.08 (95% CI 1.56 to 2.78) per 1,000 catheter days. Girls were three times more likely to develop a catheter-associated urinary tract infection than boys.
  • Adult patients (18+ years) had a catheter-associated urinary tract infection rate of 1.61 (95% CI 1.51 to 1.73) per 1,000 catheter days. Women were more likely to develop a catheter-associated urinary tract infection than men. The biggest difference in the likelihood of being infection-free was noted at 30 days of catheterisation: women 0.84 (95% CI 0.82 to 0.87) compared with men 0.92 (95% CI 0.90 to 0.93).
  • Cerebrovascular disease (hazard ratio [HR] 1.78, 95% CI 1.53 to 2.08) and paraplegia (HR 1.40, 95% CI 1.11 to 1.77) increased the likelihood of catheter-associated urinary tract infection.
  • The risk of infection from an indwelling catheter was at its highest at around 40 days.

What does current guidance say on this issue?

The NHS website overview of urinary catheters advises that the longer a catheter is used, the greater the risk of infection.

The NICE clinical guideline on healthcare-associated infections (updated 2017) advocates that the clinical need for catheterisation should be reviewed regularly and that urinary catheters are removed as soon as possible.

What are the implications?

In line with the NICE clinical guideline, the duration of catheterisation should be kept to a clinical minimum. Each additional day of catheterisation incrementally increases the risk of catheter-associated urinary tract infection.

Vigilance is warranted in regularly reviewing the clinical need of indwelling catheters, particularly in the high-risk groups.

Citation and Funding

Letica-Kriegel AS, Salmasian H, Vawdrey DK et al. Identifying the risk factors for catheter-associated urinary tract infections: a large cross-sectional study of six hospitals. BMJ Open. 2019;9:e022137.


NHS website. Overview - urinary catheter. London: Department of Health and Social Care; reviewed 2017.

NHS website. Risks - urinary catheter. London: Department of Health and Social Care; 2017.

NHS website. Urinary tract infections (UTIs). London: Department of Health and Social Care; 2017.

NICE. Healthcare-associated infections: prevention and control in primary and community care. CG139. London: National Institute for Health and Care Excellence; 2012 (updated 2017).

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