Risk Factors for Nosocomial Bacteremia Secondary to Urinary Catheter-associated Bacteriuria

A Systematic Review

Laurie J. Conway, RN, MPhil, CIC; Eileen J. Carter, PhD, RN; Elaine L. Larson, PhD, RN, FAAN, CIC


Urol Nurs. 2015;35(4):191-203. 

In This Article


The Centre for Reviews and Dissemination Guidance for Undertaking Reviews in Health Care was used to develop a review protocol (Centre for Reviews and Dissemination, 2009). Electronic searches of Medline, Scopus, the Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and the Outbreak Database were conducted with the assistance of a medical librarian. Search terms were ("urosepsis" or "bacteremia-urine" or "sepsis-urine" or "urinary tract infections-complications") or (["bacteremia" or "sepsis" or 'bloodstream infection"] and ["urinary tract" or "urinary tract infections" or "urinary catheters" or "urinary catheterization" or "bacteriuria" or 'pyuria"]). The search was limited to human studies in adults, published in English between 1983 and 2012, and was later updated through August 2014. The exact Medline search code is listed in Figure 1. Reference lists of included articles and pertinent reviews were hand searched. We chose to limit our search to the past 30 years in order to be as comprehensive as possible, while ensuring that study findings would be relevant to today's highly complex clinical practice environment. A seminal guideline for the prevention of catheter-associated urinary tract infections was published in 1983 (Wong, 1983), and recommendations in subsequent guidelines have changed little over the intervening years (Conway & Larson, 2012). Therefore, clinical research into CAB from 1983 forward is likely applicable to current catheterized patient populations and settings.

Figure 1.

Medline Search Strategy Code for Risk Factors for Nosocomial Bacteremia Secondary to Urinary Catheter-Associated Bacteriuria: A Systematic Review

We selected original, peer-reviewed research, including experimental, quasi-experimental, or observational studies; case series; and outbreak reports. We excluded grey literature, duplicate reports, reviews, single case reports, editorials, or commentaries. One researcher (LJC) initially screened all titles and abstracts, culling obviously irrelevant reports and erring on the side of over-inclusion. Then two researchers (EJC and LJC) independently screened titles and abstracts, and later, full texts. Exclusion criteria are listed in Figure 2. We excluded studies that sampled exclusively renal transplant or urology patients because these populations are known to be at higher risk for urosepsis than the general acute care population (Nicolle, 2013). We excluded studies where less than half of the patients with bacteriuria had urinary catheters, and no subgroup analysis was performed because our population of interest was patients with catheters. Factors unique to in dwelling catheters, such as bio film formation and constant but incomplete evacuation of urine from the bladder, may impact the risk for subsequent bacteremia.

Figure 2.

Summary of Search and Screening Process

The same two researchers independently extracted data from the included studies into a standard form. Data about study setting, design, sample, operational definitions, and analysis were extracted. Data about the study setting included author and affiliation, year published, country, city, institution, facility size and type, and types of units. Data about the study design included study aim, design, intervention (if any), data sources, and number of data reviewers. Data about the sample included method of recruitment and random assignment, inclusion and exclusion criteria, sample size and subgroup numbers, mean age and range, races, and disease states. Operational definitions included definitions of urinary tract infection or bacteriuria, bacteremia or sepsis, nosocomial, and health care-associated. Data about analysis included outcome variables and covariates, analytic approach, and significant and non-significant findings. Disagreements were resolved by consensus.

The quality of included observational studies was appraised using the Newcastle-Ottawa Scale (NOS) (Wells et al., n.d.). The NOS examines threats to validity common to observational studies, namely sampling bias, information bias, and confounding. It is composed of two checklists of nine items each – one for cohort studies and one for case-control studies. The NOS is recommended in the Cochrane Handbook for Systematic Reviews of Interventions (Reeves, Deeks, Higgins, & Wells, 2011). The quality of experimental studies was assessed using the Cochrane Collaboration's tool for assessing risk of bias, which assesses seven dimensions, random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other sources of bias (Higgins, Altman, & Sterne, 2011). We chose these checklists because we wanted to focus on internal validity rather than on completeness of reporting or external validity, and we wanted to identify methodological strengths and weaknesses for our outcome of interest rather than assign a rating of overall quality. Two researchers (ELL and LJC) judged the risk of bias and resolved disagreements by consensus.