Risk factors for healthcare-associated urinary tract infection and their ...

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220UTI accounted for 19.9% of HCAI, second in frequency only togastrointestinal infections (20.6%). 3 The high rate of UTI withinhospitals is commonly attributed to the use of urinary catheters,with 31.8% of the NHS patient population having undergoneurinary catheterization or bladder instrumentation on theday of the survey or in the preceding seven days. 4Traditional surveillance has long been established as anessential component to any infection prevention and controlprogramme, 5 despite the fact that it can be costly to implementand time consuming to conduct. 6 In the UK, there aremandatory surveillance systems for several HCAI, such asClostridium difficile (since January 2004) and meticillinresistantStaphylococcus aureus (MRSA) bloodstream infections(since early 2001). 7,8 Surveillance of catheter-associatedurinary tract infections (CA UTI) is now performed as part of aninitiative launched by the UK Department of Health in January2011 in order to reduce patient harm. 9 However, despite thehigh burden that HCA UTI represents to the NHS, this surveillancescheme is voluntary, focuses exclusively on CA UTI, and isstill in its infancy. The potential utility of innovative HCA UTIsurveillance tools is apparent, with current work focusing onthe development of automated systems to identify UTI usingtraditional clinical definitions. 10Hospitals routinely collect and store large amounts ofadministrative data, including information on admissions,microbiology, diagnoses and procedures. 11 Although thiswealth of data has not been widely exploited for HCAIsurveillance, integrative approaches towards the more effectiveuse of administrative data are being pioneered. 11e13Determining the utility of established risk factors for HCA UTIwithin administrative hospital data presents the opportunity todevelop and test innovative surveillance tools with thepotential to enhance traditional surveillance of UTI within thehealthcare environment.The aim of this study was to quantify the existing evidencebase of risk factors for HCA UTI, create a hierarchy of risk,identify these risks within administrative hospital data, andassess the potential of this data source for informing novelsyndromic surveillance tools.MethodsSystematic literature reviewA systematic literature review was conducted to establishan evidence base of risk factors for HCA UTI. EMBASE, PubMed/MEDLINE, Web of Science and the Cochrane Database weresearched using ‘UTI’, ‘urinary tract infection’ and ‘risk’ as thesearch terms. The Cochrane Database was included to assesswhether or not a comprehensive literature review on HCA UTIrisk factors had been undertaken previously. The searchstrategy and inclusion criteria were discussed and agreedbetween the authors, and the search was conducted by a singlereviewer in April 2011.The inclusion criteria were: (1) original research papers inEnglish; (2) clear and reasonable study design; (3) demonstratedstatistical analysis, and reported odds ratios (OR), relative risksor hazard ratios, and P-values; (4) a clear definition of HCA UTIused to diagnose ‘cases’, either based on published definitions(e.g. US Centers for Disease Control and Prevention) or positivemicrobiology, antibiotic prescription and clinical data; (5)C. King et al. / Journal of Hospital Infection 82 (2012) 219e226‘controls’ clearly stated as not diagnosed with an HCA UTI; and(6) all study participants had been exposed to ‘health care’,defined as either a hospital admission for 72 h or a readmissionwith prior exposure to health care. Those studiesinvestigating risk factors for acquiring an antimicrobial-resistantinfection vs an antimicrobial-susceptible infection wereexcluded as the controls did not meet the inclusion criteria.Critical Appraisal Skills Programme (CASP) tools, developed bythe British Public Health Resource Unit, for caseecontrol(available at: http://www.sph.nhs.uk/sph-files/casp-appraisaltools/Case%20Control%2011%20Questions.pdf/view)14 andcohort studies (available at: http://www.sph.nhs.uk/sph-files/casp-appraisal-tools/cohort%2012%20questions.pdf/view) 15were employed for critical appraisal of the papers in thisstudy as they were developed specifically for cohort andcaseecontrol studies, and have been widely used in reviewarticles. 16 For those papers describing prevalence and surveillancestudies, an ‘adjusted CASP cohort tool’ was applied,which included all the aspects considered by the CASP cohorttool 15 with the exception of the follow-up criteria. Themaximum and minimum possible CASP scores ranged from14 to 14 for cohort studies, and from 12 to 12 forcaseecontrol, prevalence and surveillance studies.Those risk factors that were associated with HCA UTI(P < 0.05) at the univariate and multivariate level wereselected for further analysis, and were defined as ‘significant’risks. An ‘independent’ risk factor was considered when itsassociated P-value was
C. King et al. / Journal of Hospital Infection 82 (2012) 219e226 221review in order to address the utility of administrative hospitaldata for the development of surveillance tools.Imperial College Healthcare NHS Trust (ICHNT) is one of thelargest NHS hospital groups in the UK, consisting of five hospitalswith 1540 beds and one central laboratory. Over 750 localdatabases have been identified within ICHNT, 11 comprisinga mixture of small departmental datasets, surveillance andlarger trust-wide systems. Data on patient demographics,diagnoses [International Classification of Diseases Version 10(ICD-10)], 19 operations and procedures (OPCS), and admissionand discharge data are stored in the large organization-widepatient administration system (PAS). Microbiology and laboratorydata are located in the laboratory information managementsystem (LIMS), and further information on antimicrobialprescribing and infection prevention and control is located inlocally performed surveillance.A comprehensive variable list and code book of the hospitaldata available for this study was created and cross-checkedagainst the list of extracted risk factors for UTI. Keywordsearches of the ICD-10 codes were performed, based on the listof HCA UTI risk factors identified during the literature review,using the World Health Organization’s online search tool(http://apps.who.int/classifications/icd10). A Microsoft Excel(2007) reference spreadsheet was generated. ICD-10 codesidentified from any included studies were also recorded on thereference spreadsheet. The process was repeated with operationand procedure codes and pathology codes using referencedatabases provided by ICHNT.In order to use hospital data for research, ethical approvalwas granted by St. Mary’s National Research Ethics Committeefor the use of administrative hospital data from ICHNT in ananonymized format, i.e. one way anonymization and removalof all patient-identifiable fields prior to data analysis (Ref. No.:09/H0712/85).ResultsThe systematic literature search returned 4109 uniquepapers. One percent were excluded for not being in English,89% had titles that were not relevant to the study question, and6% were excluded as irrelevant after abstract review. Theresults retrieved from the Cochrane Database returned norelevant studies. In total, 154 studies underwent full-textreview and 23 were ultimately included in the study(Figure 1). Of the 23 papers included, three papers werecaseecontrol studies, 20e22 13 papers were cohort studies, 23e35six papers were surveillance and prevalence studies, 4,36e40 andone paper used data derived from a large randomizedcontrolled trial database (Table I). 41The majority of studies were performed in high-incomesettings, of which two were based in the UK. 4,22 Threestudies were undertaken in the middle-income countries ofBrazil, 24 India 23 and Egypt. 39 Two studies 23,34 involved paediatricpopulations, with the remaining 21 papers addressingadult populations, including patients from generalwards, 4,20,22,26,28,36,37,39,41 patients in intensive care units(ICUs), 29e31,33,38,40 surgical patients, 35 stroke patients, 32orthopaedic patients, 27 hip fracture admissions, 21 spinalinjury patients 25 and renal transplant patients. 24The CASP scores for the three caseecontrol studies rangedfrom nine 22 to six, 20 whilst the prevalence studies, using theadjusted CASP cohort study tool, scored between five 4,37 andTitle not relevant:3668Not English: 44Criteria not met: 13134 – lacking statistics60 – inappropriate cases/controls37 – not original researchInitial search: 4109Abstract review: 441Full-text review: 154Abstract notrelevant: 243Included:23Figure 1. Systematic literature review schematic. The numbersrepresent the number of studies at each stage (e.g. 441 studiesunderwent abstract review).11 36 out of 12. The cohort studies scored between three 38 and13 35 out of 14. Of the 23 papers included, almost 80% hada CASP value within the score’s upper quartile, being six andabove for the caseecontrol, prevalence and surveillancestudies, and seven and above for the cohort studies.Of the 143 risk factors assessed in all the studies, 96 (68%)were significant and 43 were independent risk factors for HCAUTI, with six studies not performing multivariate analyses. Ofthe independent risk factors, 29 were only assessed by onestudy. Among the remaining 14 risk factors that were assessedby multiple studies, half were found to be significant in morethan one of the studies in which they were included (femalesex, increasing age, diabetes mellitus, length of hospital stay,prior stroke, urinary catheter and duration of urinary catheter).Female sex was included in all the papers for analysis andwas found to be significant in 65% of the studies. One-quarter ofthe independent risk factors were associated with urinarycatheter use and management, including colonization of thedrainage bag, 41 having more than two catheters recorded 20 andintermittent catheterization. 22In order to assess the relative importance of the significantrisk factors for HCA UTI, PAR% values were calculated for thosefactors where sufficient data were reported in the correspondingstudies. Raw data (as described in the Methods) wereextracted directly from 14 studies, while ORs were used toobtain raw data in four studies. 25,33e35 Two studies did notpublish sufficient data to enable PAR% calculations, 27,40 andthree papers were not included as these were prevalencestudies. 4,36,37 Thus, 18 of the 23 papers contributed data to thePAR% calculations. PAR% values were calculated for 35 significantrisk factors for HCA UTI, and 26 were also independent riskfactors. The remaining 17 independent risk factors did not havesufficient data for PAR% calculations.
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