Four Country Healthcare Associated Infection Prevalence Survey 2006: overview of the results

Journal of Hospital Infection (2008) 69, 230e248

Available online at www.sciencedirect.com

www.elsevierhealth.com/journals/jhin

Four Country Healthcare Associated Infection Prevalence Survey 2006: overview of the results E.T.M. Smyth a,b,*, G. McIlvenny a, J.E. Enstone c, A.M. Emmerson c, H. Humphreys d,e, F. Fitzpatrick e,f, E. Davies g, R.G. Newcombe h, R.C. Spencer c, on behalf of the Hospital Infection Society Prevalence Survey Steering Group a

Northern Ireland Healthcare Associated Infection Surveillance Centre, Belfast, UK Infection Prevention and Control, The Belfast HSC Trust, Belfast, UK c Hospital Infection Society, London, UK d Department of Clinical Microbiology, Royal College of Surgeons in Ireland, Dublin, Ireland e Department of Microbiology, Beaumont Hospital, Dublin, Ireland f Health Protection Surveillance Centre, Dublin, Ireland g National Public Health Service, Cardiff, UK h Centre for Health Sciences Research, Cardiff University, Cardiff, UK b

Received 19 February 2008; accepted 18 April 2008 Available online 11 June 2008

KEYWORDS Surveillance; Prevalence; Healthcare-associated infection; Meticillin-resistant Staphylococcus aureus (MRSA); Clostridium difficile

Summary A survey of adult patients was conducted in February 2006 to May 2006 in acute hospitals across England, Wales, Northern Ireland and the Republic of Ireland to estimate the prevalence of healthcareassociated infections (HCAIs). A total of 75 694 patients were surveyed; 5743 of these had HCAIs, giving a prevalence of 7.59% (95% confidence interval: 7.40e7.78). HCAI prevalence in England was 8.19%, in Wales 6.35%, in Northern Ireland 5.43% and in the Republic of Ireland 4.89%. The most common HCAI system infections were gastrointestinal (20.6% of all HCAI), urinary tract (19.9%), surgical site (14.5%), pneumonia (14.1%), skin and soft tissue (10.4%) and primary bloodstream (7.0%). Prevalence of MRSA was 1.15% with MRSA being the causative organism in 15.8% of all system infections. Prevalence of Clostridium difficile was 1.21%. This

* Corresponding author. Address: Northern Ireland Healthcare Associated Infection Surveillance Centre, The Royal Hospitals, Belfast BT 1Z 6BA, UK. Tel.: þ44 2890 634119. E-mail address: [email protected] 0195-6701/$ - see front matter ª 2008 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2008.04.020

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was the largest HCAI prevalence survey ever performed in the four countries. The methodology and organisation used is a template for future HCAI surveillance initiatives, nationally, locally or at unit level. Information obtained from this survey will contribute to the prioritisation of resources and help to inform Departments of Health, hospitals and other relevant bodies in the continuing effort to reduce HCAI. ª 2008 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.

Introduction The surveillance of healthcare-associated infection (HCAI), i.e. the collection of standardised data, its dissemination and the subsequent action accruing from the results, is an important aspect of infection prevention. Prevalence surveys of HCAI provide data regarding patients, at one particular point in time, and are generally easy to conduct, relatively inexpensive and are not especially time-consuming.1 Incidence surveys are more difficult to perform, especially when carried out at a national level. When conducting surveillance at a national level, a balance has to be struck between the collection of complex and detailed information and the need to decrease the load on infection control and prevention teams, while enhancing accuracy.2 National surveillance of HCAI has been introduced in North America and in many European countries, including the UK. Aggregated data on orthopaedic procedures from Scotland, Wales, and Northern Ireland (NI) (Pan Celtic collaboration) has shown a decrease in surgical site infection (SSI) rates over four years.3 In Germany, the German National Nosocomial Infection Surveillance Systems (KISS) has documented a decrease in SSI rates between the first and third years of its implementation.4 In Norway between 1996 and 1998, there was a reduction in the urinary tract infection (UTI) rate (per 100 patients) from 2.4 to 1.7, lower respiratory tract infection (LRTI) rate from 1.5 to 0.8 and a fall in postoperative wound infection rate from 5.7 to 4.3.5 Even in the absence of designated and specific intervention measures, the collection of data and the feedback of surveillance data to a wide range of healthcare professionals can have a beneficial effect in terms of HCAI prevention. National prevalence surveys of HCAI are increasingly common; recent reports include those from Greece and Spain.6,7 The overall prevalence in the Greek survey was 9.3% whereas in the most recent Norwegian survey carried out in 2002 and 2003 the prevalence varied from 5.1 to 5.4%.8 In the UK, the first national prevalence survey was carried out in

1980 and included 18 186 patients.9 The overall HCAI prevalence was 9.2%, with UTI being the most common infection. The second national prevalence survey took place over a 15-month period in 1993 and 1994 and in addition included hospitals in the Republic of Ireland (RoI). In all, 157 hospitals participated and data were collected on 37 111 patients.10 The HCAI prevalence in that survey was 9.0% but the prevalence was higher in larger/referral hospitals (11.2%) compared with smaller hospitals (8.4%). The second national prevalence survey prompted many hospitals to perform continuous surveillance in a more focused way and the intervening period has seen the establishment of mandatory reporting of meticillin-resistant Staphylococcus aureus (MRSA) bloodstream infections, Clostridium difficile, orthopaedic SSIs etc., as part of the National Health Service’s initiatives in enhancing the quality and safety of patient care. The aims of this third national prevalence survey were to determine the prevalence of all HCAI in acute hospitals including UTI, SSI, bloodstream infection, soft tissue infections, and LRTIs, with specific information to be collected on MRSA infections and C. difficile. In addition, the survey was designed to help develop a consistent methodology for prevalence surveys into the future, and to maintain compatibility with studies carried out in other countries. This report outlines the overall results from that survey.

Methods Organisation In November 2004, the Department of Health (England) requested the Hospital Infection Society (HIS) to take the lead in organising a third national prevalence survey in England. Subsequently, the Departments of Health of Wales, NI, and the RoI were invited to participate. Health Protection Scotland had already planned a similar prevalence survey for Scotland.

232 A prevalence survey steering group was established by HIS comprising HIS members, Infection Control Nurses Association (ICNA) members, representation from the NI Healthcare-Associated Infection Surveillance Centre (HISC), the Welsh Healthcare Associated Infection Programme (WHAIP), the RoI Health Protection Surveillance Centre (HPSC), and Health Protection Scotland (HPS). There was also representation from Departments of Health in England and Wales. The steering group agreed a data set, definitions and protocol. Pilot studies were conducted at three English hospitals on a variety of wards to test the proposed survey questionnaire and to refine the methodology for the definitive survey. During the summer of 2005, invitations to participate in the prevalence survey were sent to members of the HIS and the ICNA in England. The Department of Health, Social Services and Public Safety (DHSSPS) in NI issued a similar invitation to all Trusts. In the RoI the survey was organised by the HPSC. In Wales, where the survey was mandatory, WHAIP was given responsibility by the Welsh Assembly Government for co-ordinating and supporting the data collection. Children’s hospitals, mental health hospitals and military hospitals, non-acute hospitals and private hospitals were excluded from participating, except in the RoI where private hospitals participated.

Co-ordinators Co-ordinators were appointed in each country (in England an additional 11 regional co-ordinators were appointed) and trained in all aspects of the survey at an intensive three-day course. The role of the co-ordinators was to support the hospitals throughout the survey, which included assisting with planning, training, logistical and methodological issues. The co-ordinators also conducted validation studies at the time of the survey. In the RoI, the Infection Prevention and Control Teams (IPCTs) collected data assisted by the co-ordinators.

Training of hospital staff Training was given to staff, likely to be involved in data collection, at 13 symposia at venues across England, NI and the RoI during January and February 2006. The symposia included sessions on aims and objectives of the survey, the organisation and logistics, the questionnaire, definitions of infection, and the feedback strategy. Training was conducted separately at each hospital in Wales just prior to the survey being conducted.

E.T.M. Smyth et al.

Confidentiality and ethical approval The Department of Health (England) indicated that the survey did not require ethical approval. In England, Caldicott Guardians gave permission for hospital staff and regional co-ordinators to access patients’ records. The Health Services Executive in the RoI confirmed that ethical approval was not required and the co-ordinators signed confidentiality agreements. In NI, permission to access medical notes was sought from medical directors. In Wales, permission was sought from the Trust boards. On occasion, co-ordinators also signed confidentiality agreements in the hospitals before having access to patient records.

Bed selection In England and NI, hospitals provided bed numbers, which enabled the development of a sampling strategy for each hospital. The strategy proposed surveying 50% of all beds in specialties where there were more than 40 beds; 20 beds in specialties where there were between 20 and 40 beds; and 100% of beds in specialties where there were fewer than 20 beds. This formula was used to give a minimum number of beds to be surveyed. Specific ward selection was left to hospital staff. In Wales, all beds were surveyed. In the RoI, because many of the hospitals are small, a different sampling strategy was employed. This proposed that hospitals should survey all beds if there were 200 or fewer beds and at least 80% of beds if there were more than 200 beds. Acute Trusts were defined as those with 85% or more of their expenditure in acute specialties (medicine, surgery, A&E, and maternity) with an A&E department and all the core acute specialties. The Trust size categories of large, medium and small were based on expenditure per annum (small: up to £80m; medium: £80me£130m; large: more than £130m). These were based on Trust Financial Returns data for 2003/04 (personal communication). Acute Teaching Trusts were those with an attached undergraduate medical school and Acute Specialist Trusts were those with very restricted specialties. Hospitals in the RoI have not been allocated to these categories because the structure of the healthcare system differs considerably.

Patient selection Patients to be surveyed were all on adult wards including patients on adolescent units and young people on adult wards. The following groups were

HCAI prevalence survey: overview excluded: day-centre rehabilitation patients, psychiatric patients, day-case patients, accident and emergency (A&E) patients, acute medical admission unit patients, and labour suite patients. Patients not fully clerked were also excluded from the survey.

Data collection All countries collected data on individually serialised questionnaires which were designed using optical mark reader (OMR) systems [Formic 4 (Formic Ltd, London, UK): England, Wales and NI; Cardiff TeleForm (Cardiff, UK; Cambridge, UK): RoI] to capture and place data automatically in a data file when questionnaires were scanned. The data set used on the main questionnaire was identical in all countries. The questionnaire was made up of four sections. The first section included the survey date and hospital details; the second section dealt with basic patient details and related risk factors; the third section requested information about Clostridium difficile and norovirus; the final section recorded details of HCAI including whether MRSA was the causative organism. The majority of questions were answered by marking an ‘X’ in a box. A number of questions required numerical codes or dates. In order to establish whether patients met the criteria for an HCAI, staff were directed to use documentation such as medical records, nursing notes, temperature charts, x-rays and laboratory reports, and to seek additional evidence from ward staff when appropriate. Data were collected on all active HCAI as defined by the Centers for Disease Control and Prevention (CDC) definitions of nosocomial infections.11 No modifications or amendments were made to the definitions. By these definitions, an HCAI is a localised or systemic condition resulting from adverse reaction to the presence of an infectious agent(s) or its toxins. There must be no evidence that it was present or incubating at the time of hospital admission. The criteria for HCAI were to be met at the time of the survey (including being on treatment at the time of the survey for an infection that previously met the necessary criteria). Healthcareassociated infections from other hospitals were not included but a patient re-admitted with an infection due to an earlier admission to the same hospital would be considered to have an HCAI. Surgical procedures conducted in the previous 30 days (with no implant) and procedures carried out in the previous year (with an implant) were recorded. The numbers of HCAI observed on the day of the survey which related to that admission (or to

233 a readmission to the same hospital) were divided by the number of inpatients surveyed to obtain the measure of prevalence. In all countries, the prevalence survey was conducted in a 12-week period between midFebruary and May 2006. Although ideally it is best to conduct a prevalence survey over a oneday period, this was not a realistic option for most hospitals. However, wards or units had to be completed on the same day. In Wales, each hospital was allocated specific periods for data collection because of the requirement for a member of the WHAIP team to be present. In the RoI, temporary trained data collectors, with the full involvement of the local IPCTs, collected data. The Health Service Executive in the RoI funded these data collectors.

Validation Validation was conducted to check for interobserver variation between hospital staff carrying out the survey and the co-ordinators or other supervisory survey staff. The validation principally focused on the diagnosis of HCAI. All patients sampled were rated as positive or negative for HCAI by hospital staff, leading to a simple estimate of prevalence. The validation exercise was undertaken on the same day as the prevalence survey. A major purpose of these validation exercises was to supply an adjusted estimate of prevalence which attempts to reproduce what the prevalence in the whole series would have been, had all patients been assessed not by hospital staff but by those who performed the validation. Although there was some variation in approach between countries, generally at least one ward, often two wards, at each hospital were validated. However, in Wales, because there was a different data collector on each ward, rather than validating two complete wards for a hospital, w10% was validated by WHAIP staff. In the RoI, a designated member of the HPSC team performed validation within the geographical regions and included a cross-section of the hospitals represented.

Data management Completed survey forms were collated and checked for obvious errors and omissions in the hospital at the time of the survey and when possible were clarified with hospital staff. The questionnaires were then scanned with a small number of simple validation checks built into the process. The scanned data for England, NI and

234 Wales was exported to SPSS (SAS Institute, Inc., Cary, NC, USA) by the data management team at HISC in Belfast and subjected to a systematic series of detailed queries to clean the data. Examples included looking for extremes of age and inconsistent answers, e.g. a negative answer to surgery but a procedure code provided. Blank data fields were verified by referring to scanned images for marks outside of the intended tick box. The entries were then amended or deleted as appropriate. Data cleaning was carried out independently in the RoI and the data were sent to HISC where a merged database was prepared for analysis.

Data reporting A secure web-based reporting system was developed by the WHAIP team and hosted by the NHS intranet for England, Wales and NI. This allowed participants to access results for their own hospital, other hospitals within the same Trust and aggregated results for each individual country. The results included reports on prevalence of HCAI, types of infection, MRSA, and C. difficile. Reports could be subdivided by ward specialty, consultant specialty and named ward. As participants from the RoI could not access the NHS intranet and only 24/44 participating hospitals had access to the equivalent Irish intranet (E-Gov Services VPN), participants were circulated with CD-ROMs containing their results and a summary of the national results.

Evaluation survey Following completion of the study, an evaluation questionnaire was sent to participating hospitals in England, NI and the RoI; no evaluation survey was carried out in Wales. Participants were asked to comment on the survey form, protocol/manual and CDC definitions.

Statistical methods 95% confidence intervals (CIs) for HCAI prevalence were calculated using the score method (Wilson 1927).12 Odds ratios are reported for each level of each risk factor relative to a reference category, with 95% CIs calculated using the method of Miettinen and Nurminen.13 Furthermore, binary logistic regression was used to adjust differences in prevalence between countries for the confounding effect of age. In these analyses, age was entered as a categorical variable in five-year groups, to minimise the potential for residual confounding. Prevalence values and odds

E.T.M. Smyth et al. ratios are reported to within two decimal points whereas all other percentages are shown to within one decimal place.

Results The prevalence survey was conducted in 270 hospitals; 190 hospitals in England (130 Trusts); 45 hospitals in RoI; 20 hospitals in Wales (13 Trusts); 15 hospitals in NI (12 Trusts) and included 75 694 patients of which 19 984 that had undergone a surgical procedure. In England, a comparison of sampling data to actual beds surveyed was available for 90.0% (117/130) of Trusts. Of these Trusts, almost 80% (92/117) surveyed more than the number of patients requested by sampling and, of these, 19.6% (18/92) surveyed at least 50% more than requested. There were 5743 patients with one or more HCAI, giving a prevalence of 7.59% (95% CI: 7.40e7.78). The unadjusted HCAI prevalence was lowest in the RoI (4.89%) and highest in England (8.19%). There were highly significant differences in overall prevalence of HCAI between the different countries (P < 0.001) (Table I). The HCAI prevalence was lowest in Trusts categorised as medium acute and small acute (both 7.50%) and higher in Trusts categorised as acute specialist (9.25%) and acute teaching (8.32%) (Table I). Consultant specialties used in the survey were aligned with the specialties recognised in the European Specialist Medical Qualifications Order 1995 and European Primary and Specialist Dental Qualifications Regulations 1998. The consultant specialty reflected the consultant managing the patient on a day-to-day basis. These were grouped into nine categories for analysis and there were significant differences between the prevalence of HCAI in the specialty categories. The prevalence was high in critical care (23.23%) and cardiothoracic surgery (11.76%) and low in ophthalmology and ENT (3.05%) and obstetrics and gynaecology (2.23%) (Table I). Patients were also allocated to one of ten ward specialty categories. These were the same as the consultant specialty categories with the additional specialty of high dependency (HCAI prevalence 7.37%) (Table I). The mean age of patients surveyed was 67 years (median 72) with a minimum of 11 years and a maximum age of 106 years. The mean age for males was 67 years (median 71) and for females was 67 years (median 74). The mean age of patients with an HCAI was 72 years (median 76). There were more females (56.0%) than males (44.0%) in the survey population. The HCAI prevalence was significantly

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Table I Prevalence of healthcare-associated infection (HCAI) according to patient and hospital characteristics with odds ratios No. of patients No. of Prevalence of (% of total patients HCAI patients) with HCAI

95% CI

Chi-squared test

Odds ratio (95% CI)

Country Overall England Northern Ireland Wales Republic of Ireland

75 694 58 775 3644 5734 7541

(100) (77.6) (4.8) (7.6) (10)

5743 4812 198 364 369

7.59 8.19 5.43 6.35 4.89

7.40e7.78 7.97e8.41 4.74e6.22 5.75e7.01 4.43e5.40

Trust typea Large acute Medium acute Acute teaching Small acute Acute specialist

23 927 19 637 16 301 6840 1448

(31.2) (25.9) (22.0) (9.0) (1.9)

1899 1472 1356 513 134

7.94 7.50 8.32 7.50 9.25

7.60e8.29 P ¼ 0.009 7.14e7.87 7.90e8.75 6.90e8.15 7.87e10.86

1.00 0.94 1.05 0.94 1.18

Sex Male Female

33 240 (44) 42 215 (56)

2661 3061

8.01 7.25

7.72e8.30 7.01e7.50

P < 0.001

1.11 (1.05e1.17) 1.00

Age group (years) <35 35e64 65e84 85

6811 20 308 34 739 13 526

(9.0) (26.9) (45.9) (17.9)

217 1300 2877 1327

3.19 6.40 8.28 9.81

2.79e3.63 P < 0.001 6.07e6.75 8.00e8.58 9.32e10.32

0.36 (0.32e0.42) 0.76 (0.71e0.81) 1.00 1.20 (1.13e1.29)

Consultant specialty group General medicine 44 862 (59.5) General surgery 12 677 (16.8) Trauma & orthopaedics 8877 (11.8) Obstetrics & gynaecology 4743 (6.3) Cardiothoracic surgery 1207 (1.6) Ophthalmology & ENT 1113 (1.5) Neurosurgery 962 (1.3) Critical care medicine 465 (0.6) Others 478 (0.6)

3445 1000 740 106 142 34 101 108 48

7.68 7.89 8.34 2.23 11.76 3.05 10.50 23.23 10.04

7.44e7.93 P < 0.001 7.43e8.37 7.78e8.93 1.85e2.70 10.07e13.70 2.19e4.24 8.72 e12.60 19.62e27.27 7.66e13.06

1.00 1.03 1.09 0.27 1.60 0.38 1.41 3.64 1.34

(0.96e1.11) (1.01e1.19) (0.23e0.33) (1.34e1.92) (0.27e0.53) (1.14e1.74) (2.93e4.52) (1.00e1.81)

Ward specialty group General medicine 39 885 (52.7) General surgery 13 741 (18.2) Trauma & orthopaedics 9064 (12.0) Obstetrics & gynaecology 5254 (6.9) Cardiothoracic surgery 1191 (1.6) Ophthalmology & ENT 1461 (1.9) Neurosurgery 826 (1.1) Critical care medicine 1924 (2.5) High dependency 801 (1.1) Others 1547 (2.0)

3153 892 726 118 120 49 78 448 59 100

7.91 6.49 8.01 2.25 10.08 3.35 9.44 23.28 7.37 6.46

7.64e8.17 P < 0.001 6.09e6.92 7.47e8.59 1.88e2.68 8.49e11.92 2.55e4.41 7.63e11.63 21.45e25.23 5.75e9.39 5.34e7.80

1.00 0.81 1.01 0.27 1.31 0.40 1.21 3.54 0.93 0.81

(0.75e0.87) (0.93e1.10) (0.22e0.32) (1.08e1.58) (0.30e0.54) (0.96e1.54) (3.16e3.95) (0.71e1.21) (0.66e0.99)

P < 0.001 1.00 0.64 (0.56e0.75) 0.76 (0.68e0.85) 0.58 (0.52e0.64)

(0.88e1.01) (0.98e1.13) (0.85e1.04) (0.98e1.42)

ENT, ear, nose and throat; CI, confidence interval. Acute (small, medium and large): Trusts with 85% or more of their expenditure in acute specialties [medicine, surgery, accident and emergency (A&E) and maternity] with an A&E department and all the core acute specialties. The size categories are based on expenditure per annum: small: up to £80m; medium: £80e130m; large: more than £130m; based on Trust Financial Returns figures for 2003/4. Acute Teaching: Trusts with an attached undergraduate medical school. Acute Specialist: Trusts with very restricted specialties. a Excludes Republic of Ireland. Hospitals in the Republic of Ireland have not been allocated to these categories because the healthcare system differs significantly so such allocation was inappropriate.

236

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higher in males (8.01%) than in females (7.25%), with an odds ratio of 1.11 (95% CI: 1.05e1.17) for males compared to females (Table I). Prevalence of HCAI increased significantly with age. In the RoI, almost half the patients were aged <65 years compared with only w35% in the other countries. A logistic regression model was obtained for HCAI by country adjusting for age. The odds ratios comparing NI, Wales and the RoI with England before adjustment for age are shown in Table I and the odds ratios after adjustment for age were 0.66, 0.76 and 0.61, respectively. The highest HCAI prevalence for a hospital was 34.6%. Nine hospitals recorded no patients with an HCAI. The distribution of HCAI prevalence varied between countries and is illustrated in Table II and Figure 1. In total, there were 6385 system infections in 5743 patients. Of these patients, 5212 (90.7%) had only one system infection, 483 (8.4%) had two, 67 (1.2%) had three, 10 (0.2%) had four and one (0.02%) patient had five system infections. The most common HCAI system infections were gastrointestinal (20.6% of all HCAI), urinary tract (19.9%), surgical site (14.5%), pneumonias (14.1%), skin and soft tissue (10.4%) and primary bloodstream (7.0%) (Table III). It should be noted that the prevalence of SSI is the highest of all system infections because the denominator is a subset of the total patients surveyed, i.e. patients who had undergone surgery. The HCAI prevalence for system infection by country is presented in Table IV. There was a statistically significant difference in prevalence between the countries for eight of the 13 system infections; for gastrointestinal system infections, England was statistically significantly higher than the other countries (Table IV). For each system infection, it was recorded whether MRSA was the causative organism. The overall prevalence of MRSA was 1.15% (873 patients) with MRSA being the causative organism in 15.8% of all HCAIs (1009 MRSA infections out of

Table II Distribution of healthcare-associated infection (HCAI) prevalence by country Prevalence HCAI range

0e5% 5.01e10% 10.01e15% 15.01e20% >20%

Percentage of hospitals England Wales

25.3 51.0 17.4 4.2 2.1

30.0 70.0 0 0 0

Northern Ireland

Republic of Ireland

60.0 33.3 6.7 0 0

66.7 31.1 2.2 0 0

6385 total infections). The prevalence of MRSA differs significantly between the four countries, age group, specialty groups and genders (Table V). The prevalence of HCAI by system infection where MRSA was the causative organism is presented in Table VI. Data are also presented in Table VI regarding the percentage of total MRSA infection related to system infection. Table VII shows the distribution of MRSA infection prevalence by system infection and country. In addition to information regarding whether MRSA was the causative organism, data were collected on whether the system infection was device-related, and whether a secondary bloodstream infection was associated with the infection. Further information was collected on UTIs, pneumonias, SSIs and primary bloodstream infections. Of the 1272 patients with UTIs, 863 (67.8%) were recorded as symptomatic, 353 (27.8%) as asymptomatic and 41 (3.2%) as other infections of the urinary tract. At the time of the survey, patients with a urinary catheter, either in situ or within the previous seven days, accounted for 30.2% of the patient population; in England it was 31.6%, in NI 29.2%, in Wales 25.5% and in the RoI 23.2%. More than half of UTIs (707, 55.6%) were recorded as catheter-related; in England 57.3% of UTIs were catheter-related, in NI 50.7%, in Wales 40.3% and in the RoI 49.4% were catheter-related. There were marked differences in the UTI prevalence between England/NI and Wales/RoI (Table IV). A logistic regression model was developed that took into account country, catheter use, age group, and gender simultaneously. This indicated that the w40% lower UTI prevalence in Wales/RoI was minimally accounted for by differences in catheter use and to only a modest degree by demographics. Nine hundred patients had healthcareassociated pneumonia, of which the majority (719, 79.9%) were clinically defined, and 18.4% were ventilator-associated. There were 449 patients with a primary bloodstream infection; of these, 184 (41.0%) were central line-related, i.e. the patient had a central line during the 48 h period before developing primary bloodstream infection. Of the 929 recorded SSIs, 417 (44.9%) were superficial incisional, 329 (35.4%) were deep incisional and 170 (18.3%) were organ/space. The SSI prevalence for surgical procedure categories with more than 250 procedures and associated MRSA prevalence are provided in Table VIII. Information was collected on whether patients currently had C. difficile infection. In total, 1303

HCAI prevalence survey: overview 100%

237

4.2

2.2

6.7

90% 17.4 31.1

80% 33.3

Percentage of hospitals

70% 70 60% 50%

51

40% 66.7 30%

60

20% 10% 0%

25.3

England

30

Wales

Northern Ireland

Republic of Ireland

Figure 1 Distribution of healthcare-associated infection prevalence by country. Black: 15.01e20%; stippled: 10.01e15%; hatched: 5.01e10%; white: 0e5%.

Table III

Types and prevalence of healthcare-associated infection (HCAI)

System infection Gastrointestinal systema Urinary tract Urinary tract e catheter-related Surgical site All patients Patients who had undergone surgery Pneumonia Pneumonia e ventilator-associated Skin & soft tissue Primary bloodstream Primary bloodstream e central line-related Lower respiratory tract (not pneumonia) Eyes, ENT or mouth Bone and joint Systemic Cardiovascular system Reproductive tract Central nervous system Secondary bloodstream infectionb

No. of infections

Prevalence of HCAI by system infection

95% CI

% of total HCAI

1320 1272 709

1.74 1.68 0.94

1.65e1.84 1.59e1.77 0.87e1.01

20.6 19.9

929 929 900 166 665 449 184 402 180 75 70 67 40 16 197

1.23 4.65 1.19 0.22 0.88 0.59 0.24 0.53 0.24 0.10 0.09 0.09 0.05 0.02 0.26

1.15e1.31 4.37e4.95 1.11e1.27 0.19e0.26 0.81e0.95 0.54e0.65 0.21e0.28 0.48e0.59 0.21e0.28 0.08e0.12 0.07e0.12 0.07e0.11 0.04e0.07 0.01e0.03 0.23e0.30

14.5 14.1 10.4 7.0 6.3 2.8 1.2 1.1 1.1 0.7 0.3 e

a Gastrointestinal system infections include gastroenteritis, other gastrointestinal tract infections (of the oesophagus, stomach, small and large bowel and rectum), hepatitis and other intra-abdominal infections. b Secondary bloodstream infection: the patient has a culture-confirmed bloodstream infection and a related HCAI at another site.

Prevalence of healthcare-associated infection system infection by country

System infection Gastrointestinal systema

Urinary tract

Surgical site e surgical patients only

Pneumonia

Skin & soft tissue

Primary bloodstream

Lower respiratory tract (not pneumonia)

Eyes, ENT

Bone and joint

Country

No. of infections

Prevalence

95% CI

England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI

1185 28 62 45 1060 67 62 83 744 30 72 83 749 47 39 65 562 17 50 36 366 14 32 37 323 9 57 13 157 0 12 11 64 4 4 3 63 0 6 1

2.02 0.77 1.08 0.60 1.80 1.84 1.08 1.10 4.65 3.69 5.35 4.56 1.27 1.29 0.68 0.86 0.96 0.47 0.87 0.48 0.62 0.38 0.56 0.49 0.55 0.25 0.99 0.17 0.27 0.00 0.21 0.15 0.11 0.11 0.07 0.04 0.11 0.00 0.10 0.01

1.91e2.13 0.53e1.11 0.84e1.38 0.45e0.80 1.70e1.91 1.45e2.33 0.84e1.38 0.89e1.36 4.33e4.99 2.59e5.21 4.27e6.68 3.69e5.62 1.19e1.37 0.97e1.71 0.50e0.93 0.68e1.10 0.88e1.04 0.29e0.75 0.66e1.15 0.35e0.66 0.56e0.69 0.23e0.64 0.40e0.79 0.36e0.68 0.49e0.61 0.13e0.47 0.77e1.29 0.10e0.29 0.23e0.31 0.00e0.11 0.12e0.37 0.08e0.26 0.09e0.14 0.04e0.28 0.03e0.18 0.01e0.12 0.08e0.14 0.00e0.11 0.05e0.23 0.00e0.08

Chi-squared test P < 0.001

P < 0.001

P ¼ 0.36

P < 0.001

P < 0.001

P ¼ 0.17

P < 0.001

P ¼ 0.003

P ¼ 0.29

P ¼ 0.019

Odds ratio (95% CI) 1.00 0.38 0.53 0.29 1.00 1.02 0.60 0.61 1.00 0.78 1.16 0.98 1.00 1.01 0.53 0.67 1.00 0.49 0.91 0.50 1.00 0.62 0.90 0.79 1.00 0.45 1.82 0.31 1.00 0.00 0.78 0.55 1.00 1.01 0.64 0.37 1.00 0.00 0.98 0.12

(0.26e0.55) (0.41e0.69) (0.22e0.39) (0.80e1.31) (0.46e0.77) (0.48e0.76) (0.54e1.14) (0.90e1.49) (0.78e1.23) (0.75e1.36) (0.38e0.73) (0.52e0.87) (0.30e0.78) (0.68e1.22) (0.35e0.70) (0.36e1.04) (0.62e1.28) (0.56e1.10) (0.23e0.86) (1.37e2.41) (0.18e0.54)

Odds ratio adjusted for age (95% CI) 1.00 0.40 (0.28e0.59) 0.53 (0.41e0.68) 0.34 (0.25e0.45) 1.00 1.09 (0.85e1.40) 0.60 (0.46e0.78) 0.70 (0.55e0.87) 1.00 0.79 (0.55e1.15) 1.14 (0.89e1.47) 0.96 (0.76e1.21) 1.00 1.00 (0.74e1.35) 0.52 (0.38e0.73) 0.70 (0.55e0.91) 1.00 0.50 (0.31e0.80) 0.90 (0.67e1.21) 0.51 (0.36e0.71) 1.00 0.60 (0.35e1.02) 0.89 (0.62e1.28) 0.72 (0.51e1.01) 1.00 0.47 (0.24e0.90) 1.81 (1.36e2.41) 0.33 (0.18e0.57) Not measured

(0.00e0.39) (0.44e1.40) (0.30e1.00) Not measured (0.38e2.66) (0.24e1.69) (0.12e1.10) Not measured (0.00e0.98) (0.43e2.21) (0.02e0.71)

E.T.M. Smyth et al.

Systemic

238

Table IV

(0.27e1.34) (0.76e1.95) (0.33e1.04) P ¼ 0.13

P ¼ 0.75

P ¼ 0.78

Secondary bloodstream infectionb

Central nervous system

Reproductive tract

239 RoI, Republic of Ireland; ENT, ear, nose and throat; CI, confidence interval. a Gastrointestinal system infections include gastroenteritis, other gastrointestinal tract infections (of the oesophagus, stomach, small and large bowel and rectum), hepatitis and other intra-abdominal infections. b Secondary bloodstream infection: The patient has a culture-confirmed bloodstream infection and a related HCAI at another site.

Not measured (0.00e4.43) (0.12e4.36) (0.09e3.31)

Not measured (0.26e3.69) (0.30e2.86) (0.13e1.78)

Not measured Cardiovascular system

England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI

61 0 0 6 33 2 3 2 14 0 1 1 160 6 19 12

0.10 0.00 0.00 0.08 0.06 0.05 0.05 0.03 0.02 0.00 0.02 0.01 0.27 0.16 0.33 0.16

0.08e0.13 0.00e0.11 0.00e0.07 0.04e0.17 0.04e0.08 0.02e0.20 0.02e0.15 0.01e0.10 0.01e0.04 0.00e0.11 0.00e0.10 0.00e0.08 0.23e0.32 0.08e0.36 0.21e0.52 0.09e0.28

P ¼ 0.019

1.00 0.00 0.00 0.77 1.00 0.98 0.93 0.47 1.00 0.00 0.73 0.56 1.00 0.60 1.22 0.58

(0.00e1.01) (0.00e0.64) (0.34e1.73)

1.00 0.60 (0.27e1.37) 1.09 (0.66e1.80) 0.58 (0.32e1.04)

HCAI prevalence survey: overview

patients were identified with C. difficile infection (1.72% of the patient population). This number included patients with hospital-associated C. difficile infection (917 patients, 1.21%) and those with community-associated C. difficile infection (386 patients, 0.51%). Table IX shows the prevalence of HCAI C. difficile infection according to patient, Trust type, and country. Approximately one-third of patients (33.1%) were being treated with antimicrobials at the time of the survey with approximately half of these patients [11 696 (15.4% of all patients)] on intravenous antimicrobial therapy. Of those patients with an HCAI, 79.4% were receiving antibiotics at the time of the survey. The most common devices used were peripheral catheters (62.8% of patients) and urinary catheters (30.9% of patients) which were either in situ or present within the seven days before the survey was conducted.

Evaluation survey The overall response rate to the evaluation survey in England, NI, and the RoI was 67.2% (168/250). In England and NI evaluation questionnaire responses were returned anonymously with a collective response rate of 62.0% (127/205). In the RoI, 91.1% (41/45) of participating hospitals returned the evaluation. The evaluations indicated that the composition of the data collection team in participating hospitals varied and involved a range of healthcare professionals including microbiologists [62.5% (105/168)], infection prevention and control nurses (100%), ward staff [69.6% (117/168)] and infection control link professionals [25.0% (42/168)]. Overall, participants were satisfied with the layout of the survey form, the protocol/manual, and CDC definitions, with the pneumonia definitions considered to be the most difficult to apply. A majority of centres surveyed more beds than the minimum number they were requested to survey according to the sampling formula. Fifty-five respondents (32.7%) had participated in the previous HIS/ICNA prevalence survey and the majority [76.4% (42/55)] found the current survey easier to perform. Most respondents [91.7% (154/168)] would consider using the questionnaire for repeat surveys in their hospital and almost all respondents [97.0% (163/168)] indicated that they would be willing to participate in future national HCAI surveillance initiatives. However, in the RoI virtually all (39/41 respondents) felt they could only do so with additional IPCT resources. Problems with medical [61.3% (103/168)], nursing

240 [74.4% (125/168)] and device-related documentation [74.4% (125/168)] were highlighted.

Validation In the validation database for England and NI there were 4716 matched pairs of which 377 were from NI. In NI there were no discrepancies between the HCAIs recorded by the hospital staff and those validated by the co-ordinator; therefore, there is no adjustment to be made to the crude prevalence value. In England, there were 4339 validation pairs matched allowing for minor discrepancies. Applying the positive and negative predictive values (PPVs and NPVs) gives an adjusted value of 7.85% as the best estimate of prevalence for the English series (unadjusted 8.19%). A resampling (bootstrap) 95% CI for this adjusted prevalence is from 7.36% to 8.35%. In Wales, a member of the WHAIP team assessed a partial validation series comprising of 667 of the 5734 patients. Taking their rating as the gold standard, PPV and NPV values of hospital staff in diagnosing HCAI were assessed. Applying the PPV and NPV gives an adjusted value of 5.03% as the best estimate of prevalence for the Welsh series (unadjusted 6.35%). A resampling (bootstrap) 95% CI for this adjusted prevalence is from 4.07 to 6.08%.

Discussion This is the largest prevalence survey of HCAI ever conducted in England, Wales, NI and the RoI. The importance of HCAI to the Departments of Health of the four countries was demonstrated by the commissioning and funding of the survey. Concern regarding HCAI amongst healthcare providers and infection prevention and control teams is emphasised by the high rate of participation in the survey. The survey was mandatory in Wales. Voluntary participation in the other countries resulted in 77% of Trusts in England, 100% of Trusts in NI and 88% of hospitals in the RoI taking part. A small number of Trusts decided not to participate. This appeared to be because of concerns regarding the workload rather than reservations about the data being used to construct league tables or the results used as a performance indicator. The primary aim of the survey was to assess the prevalence of HCAI in acute hospitals. This was achieved and hospitals or Trusts were provided with individual results via a web-based reporting system within a year of completing the survey. A second aim was to develop a methodology that could be used for future surveys and that would be

E.T.M. Smyth et al. compatible with prevalence surveys conducted in other countries. Convening a prevalence survey steering group enabled the production of an agreed data set and definitions that were used in the four countries. The use of standard CDC definitions of infection allows comparison with other prevalence surveys using the same definitions. The 1993/4 prevalence survey was primarily conducted by IPCTs. It was felt that with the increase in the workload for IPCTs since the last survey it would be beneficial to have local support to help with the logistics. The organisational and supervisory role of the co-ordinators helped to ensure that the survey was completed within the allotted 12-week time scale. The three-day training course given to the co-ordinators and the regional symposia for participating hospitals provided a sound framework for the survey to be conducted in a consistent and correct manner and greatly contributed to its success. We would hope the training in surveillance methodology and correct application of HCAI definitions will provide a basis for future HCAI surveillance initiatives. The authors feel that the use of paper questionnaires has many advantages over information technology solutions, including cost, training, accessibility, maintenance, compatibility, and speed. Dissemination of results using the webbased system, developed by WHAIP in Cardiff, provided individual hospitals with more comprehensive and timely information compared to the 1993/4 survey. The use of standardised definitions, data collection period and data collection tool by the four participating countries enables valid comparisons to be made of HCAI prevalence. This cannot occur with prevalence surveys that used different definitions of HCAI, and comparisons are difficult to make between surveys that did not include all types of HCAI. For example, some restrict their studies to the historically most common infections and so valid comparisons of overall prevalence cannot be made, although specific infection comparisons can be made.8,14 Others restrict the survey to particular specialties only, for example, Gastmeier et al. surveyed surgical, medical, gynaecological and intensive therapy unit wards only.15 We should not compare the current results with the previous prevalence surveys in the UK and Ireland, where different definitions were used nor with studies that use modified definitions.8e10 It is also not possible to compare the results of this survey to other surveys where the inclusion criteria differed. For example, some surveys restrict inclusion to those patients who have been in hospital 48 h, therefore using a different denominator to

HCAI prevalence survey: overview

241

Table V Prevalence of meticillin-resistant Staphylococcus aureus (MRSA) healthcare-associated infection according to patient and hospital characteristics with odds ratios No. of patients No. of Prevalence (percentage of patients of MRSA total patients) with MRSA

95% CI

Chisquared test

Odds ratio (95% CI)

Country Overall England Northern Ireland Wales Republic of Ireland

75 694 58 775 3644 5734 7541

(100) (77.6) (4.8) (7.6) (10)

873 755 31 50 37

1.15 1.28 0.85 0.87 0.49

1.08e1.23 1.20e1.38 0.60e1.20 0.66e1.15 0.36e0.68

P < 0.001

Trust type Large acute Medium acute Acute teaching Small acute Acute specialist

23 927 19 637 16 301 6840 1448

(31.2) (25.9) (22.0) (9.0) (1.9)

296 218 217 85 20

1.24 1.11 1.33 1.24 1.38

1.10e1.39 0.97e1.27 1.17e1.52 1.01e1.53 0.90e2.12

P < 0.41

Gender Male Female

33 240 (44) 42 215 (56)

470 401

1.41 0.95

1.29e1.55 0.86e1.05

P < 0.001

1.50 (1.31e1.71) 1.00

Age group (years) <35 35e64 65e84 85

6811 20 308 34 739 13 526

(9.0) (26.9) (45.9) (17.9)

26 224 450 171

0.38 1.10 1.30 1.26

0.26e0.56 0.97e1.26 1.18e1.42 1.09e1.47

P < 0.001

0.29 (0.20e0.43) 0.85 (0.72e1.00) 1.00 0.98 (0.82e1.16)

Consultant specialty group General medicine General surgery Trauma & orthopaedics Obstetrics & gynaecology Cardiothoracic surgery Ophthalmology & ENT Neurosurgery Critical care medicine Others

44 862 12 677 8877 4743 1207 1113 962 465 478

(59.5) (16.8) (11.8) (6.3) (1.6) (1.5) (1.3) (0.6) (0.6)

487 186 118 5 18 6 21 19 9

1.09 1.47 1.33 0.11 1.49 0.54 2.18 4.09 1.88

0.99e1.19 1.27e1.69 1.11e1.59 0.05e0.25 0.95e2.35 0.25e1.17 1.43e3.31 2.63e6.29 0.99e3.54

P < 0.001

1.00 1.36 1.23 0.10 1.38 0.49 2.03 3.88 1.75

(1.14e1.61) (1.00e1.50) (0.04e0.23) (0.86e2.21) (0.22e1.08) (1.31e3.15) (2.44e6.17) (0.91e3.36)

Ward specialty group General medicine General surgery Trauma & orthopaedics Obstetrics & gynaecology Cardiothoracic surgery Ophthalmology & ENT Neurosurgery Critical care medicine High dependency Others

39 885 13 741 9064 5254 1191 1461 826 1924 801 1547

(52.7) (18.2) (12.0) (6.9) (1.6) (1.9) (1.1) (2.5) (1.1) (2.0)

435 179 111 6 16 9 23 65 11 18

1.09 1.30 1.22 0.11 1.34 0.62 2.78 3.38 1.37 1.16

0.99e1.20 1.13e1.51 1.02e1.47 0.05e0.25 0.83e2.17 0.32e1.17 1.86e4.14 2.66e4.28 0.77e2.44 0.74e1.83

P < 0.001

1.00 1.20 1.12 0.10 1.23 0.56 2.60 3.17 1.26 1.07

(1.00e1.43) (0.91e1.39) (0.05e0.23) (0.75e2.03) (0.29e1.08) (1.70e3.96) (2.44e4.13) (0.70e2.29) (0.67e1.71)

1.00 0.66 (0.46e0.94) 0.68 (0.51e0.90) 0.38 (0.27e0.53)

1.00 0.90 1.08 1.00 1.12

(0.75e1.07) (0.90e1.28) (0.79e1.28) (0.71e1.76)

ENT, ear, nose and throat; CI, confidence interval.

studies that do not exclude such patients.16 Although theoretically feasible, converting prevalence data to incidence rates is of questionable validity and therefore not recommended.17e19 Berthelot et al. reported that calculating incidence rates from the

results of periodic prevalence surveys produced rates lower than the associated prevalence rate; however, the difference was consistent over time. Therefore, where it is not possible to collect incidence data, the data from periodic prevalence surveys may be used

242

E.T.M. Smyth et al.

Table VI Meticillin-resistant Staphylococcus aureus (MRSA) healthcare-associated infection (HCAI) by system infection and percentage of total MRSA System infection Skin & soft tissue Surgical site e patients who had undergone surgery Primary bloodstream Lower respiratory tract (not pneumonia) Pneumonia Urinary tract Ear, nose and throat Secondary bloodstream infectionb Gastrointestinal systemc Bone and joint Cardiovascular system Reproductive tract Systemic Central nervous system

No. of MRSA infections

Prevalence of MRSA by infection type

95% CI

% of total MRSA

315 228

0.42 1.14a

0.37e0.46 1.00e1.30

31.2 22.6

96 70

0.13 0.09

0.10e0.15 0.07e0.12

9.5 6.9

65 60 50 46

0.09 0.08 0.07 0.06

0.07e0.11 0.06e0.10 0.05e0.09 0.05e0.08

6.4 5.9 5.0 4.6

22

0.03

0.02e0.04

2.2

21 14 11 9 2

0.03 0.02 0.01 0.01 0.003

0.02e0.04 0.01e0.03 0.01e0.03 0.01e0.02 0.00e0.01

2.1 1.4 1.1 0.9 0.2

a

Prevalence calculated on only those patients exposed to the risk, i.e. a surgical procedure. Secondary bloodstream infection: the patient has a culture-confirmed bloodstream infection and a related HCAI at another site. c Gastrointestinal system infections include gastroenteritis, other gastrointestinal tract infections (of the oesophagus, stomach, small and large bowel and rectum), hepatitis and other intra-abdominal infections. b

to calculate incidence rates, although the authors highlight limitations of this method.20 We did not attempt a prevalence/incidence conversion in this study. The recent survey in Scotland reported a prevalence of 9.50%, although the definitions used were different from those employed in this survey.21 The overall prevalence of HCAI in England is significantly higher than the other three countries (P < 0.001). The distribution of prevalence varied between the four countries, ranging from 8.19 to 4.89%. The distribution also varied by Trust type; the highest prevalence of HCAI was found in the acute specialist Trust type that may be regarded as an ‘outlier’ as it accounted for only 1.9% of the caseload. These differences probably reflect the complexities of the case-mix found in the Trust types. More than 75% of hospitals in all four countries had an overall prevalence of HCAI of 10%. Only 45 hospitals in England, one in NI, one in RoI and no hospital in Wales had an overall prevalence of >10%. Males had a significantly higher prevalence of HCAI than females. This is consistent with previous surveys.22,23 Males were 1.5 times more likely to have an MRSA infection than females (P < 0.001); however, females were more likely to have

a hospital-associated C. difficile infection than males (P ¼ 0.025). The latter may be partly explained by females having a greater median age than males, and the prevalence of hospital-associated C. difficile was more prevalent in those aged 65 years. In addition, age distribution varied from country to country. As expected, the prevalence of infection increased with age. In the RoI, almost half the patients were aged <65 years compared with only w35% in the other countries. Age was clearly a determinant of HCAI prevalence; however, adjustment for age differences only slightly attenuated the difference between England and Ireland (NI and the RoI). Adjustment for age produced no difference between England and Wales. The highest HCAI prevalence was in highdependency areas such as critical care (23.23%) and the specialist surgical categories (neurosurgery 10.50% and cardiothoracic surgery 11.76%). In these specialties, there was a higher prevalence of primary bloodstream and pneumonia infections compared with general wards where patients would not be ventilated and invasive procedures and device usage is less common. There were minimal differences of no statistical significance in the HCAI prevalence between the

HCAI prevalence survey: overview

Table VII

243

Prevalence of meticillin-resistant Staphylococcus aureus infection by system infection and country

System infection Skin & soft tissue

Surgical site e surgical patients only

Primary bloodstream

Lower respiratory tract (not pneumonia)

Pneumonia

Urinary tract

Eyes, ENT

Secondary bloodstream infectiona

Gastrointestinal systemb

Bone and joint

Cardiovascular system

Reproductive tract

Systemic

Central nervous system

England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI England N. Ireland Wales RoI

No. of infections

Prevalence

95% CI

Chi-squared test

279 10 19 7 205 4 12 7 82 5 4 5 51 3 11 5 55 5 1 4 50 4 0 6 46 0 3 1 36 2 7 1 17 1 4 0 18 1 0 2 12 0 0 2 8 2 1 0 8 0 1 0 2 0 0 0

0.47 0.27 0.33 0.09 1.28 0.49 0.89 0.38 0.14 0.14 0.07 0.07 0.09 0.08 0.19 0.07 0.09 0.14 0.02 0.05 0.09 0.11 0.00 0.08 0.08 0.00 0.05 0.01 0.06 0.05 0.12 0.01 0.03 0.03 0.07 0.00 0.03 0.03 0.00 0.03 0.02 0.00 0.00 0.03 0.01 0.05 0.02 0.00 0.01 0.00 0.02 0.00 0.003 0.00 0.00 0.00

0.42e0.53 0.15e0.50 0.21e0.52 0.04e0.19 1.12e1.47 0.19e1.26 0.51e1.55 0.19e0.79 0.11e0.17 0.06e0.32 0.03e0.18 0.03e0.16 0.07e0.11 0.03e0.24 0.11e0.34 0.03e0.16 0.07e0.12 0.06e0.32 0.00e0.10 0.02e0.14 0.06e0.11 0.04e0.28 0.00e0.07 0.04e0.17 0.06e0.10 0.00e0.11 0.02e0.15 0.00e0.08 0.04e0.08 0.02e0.20 0.06e0.25 0.00e0.08 0.02e0.05 0.00e0.16 0.03e0.18 0.00e0.05 0.02e0.05 0.00e0.16 0.00e0.07 0.01e0.10 0.01e0.04 0.00e0.11 0.00e0.07 0.01e0.03 0.01e0.03 0.02e0.20 0.00e0.10 0.00e0.05 0.01e0.03 0.00e0.11 0.00e0.10 0.00e0.05 0.00e0.01 0.00e0.11 0.00e0.07 0.00e0.05

P < 0.001

P ¼ 0.001

P ¼ 0.22

P ¼ 0.074

P ¼ 0.13

P ¼ 0.16

P ¼ 0.069

P ¼ 0.095

P ¼ 0.14

P ¼ 0.62

P ¼ 0.55

P ¼ 0.16

P ¼ 0.65

P ¼ 0.90

Odds ratio (95% CI) 1.00 0.58 0.70 0.19 1.00 0.38 0.69 0.30 1.00 0.98 0.50 0.47 1.00 0.95 2.21 0.76 1.00 1.47 0.19 0.57 1.00 1.29 0.00 0.94 1.00 0.00 0.67 0.20 1.00 0.90 1.99 0.22 1.00 0.95 2.41 0.00 1.00 0.90 0.00 0.87 1.00 0.00 0.00 1.30 1.00 4.03 1.28 0.00 1.00 0.00 1.28 0.00 1.00 0.00 0.00 0.00

(0.31e1.07) (0.44e1.11) (0.09e0.41) (0.15e0.99) (0.39e1.23) (0.14e0.62) (0.41e2.36) (0.19e1.31) (0.20e1.14) (0.31e2.87) (1.17e4.20) (0.31e1.86) (0.60e3.56) (0.03e1.07) (0.21e1.50) (0.48e3.44) (0.00e0.79) (0.41e2.13) (0.00e1.35) (0.22e2.03) (0.03e1.15) (0.24e3.37) (0.91e4.39) (0.04e1.25) (0.16e5.60) (0.85e6.84) (0.00e1.76) (0.15e5.28) (0.00e2.19) (0.22e3.36) (0.00e5.16) (0.00e3.28) (0.33e5.18) (0.97e16.8) (0.21e7.89) (0.00e3.74) (0.00e7.75) (0.21e7.89) (0.00e3.74) (0.00e31.0) (0.00e19.7) (0.00e15.0)

RoI, Republic of Ireland; ENT, ear, nose and throat; CI, confidence interval. a Secondary bloodstream infection: the patient has a culture-confirmed bloodstream infection and a related HCAI at another site. b Gastrointestinal system infections include gastroenteritis, other gastrointestinal tract infections (of the oesophagus, stomach, small and large bowel and rectum), hepatitis and other intra-abdominal infections.

244

E.T.M. Smyth et al.

Table VIII Surgical site infection (SSI) prevalence by surgical procedure categorya and meticillin-resistant Staphylococcus aureus (MRSA)-related SSIs Procedure category

No. of surgical procedures

Prevalence of surgical site infection

Prevalence of MRSA SSI

434 257 387 360 1197 454

10.14 9.73 8.79 8.33 8.27 8.15

4.38 2.33 2.33 2.22 1.84 1.10

344 257 389 338 296 259 1538 1133 319 3044 495 364 2121 358 738 875 613

6.40 5.84 5.66 4.44 4.39 4.25 4.23 4.15 4.08 4.07 3.84 3.30 3.11 2.79 2.30 1.49 0.82

1.74 0.78 0.51 1.18 0.34 0.77 1.30 0.88 0.00 1.15 0.40 1.10 1.04 0.28 0.81 0.00 0.33

253 287

0.79 0.70

0.00 0.00

Limb amputation Peripheral vascular bypass surgery Small bowel surgery Abdominal surgery Colon surgery Coronary artery bypass graft with both chest and donor site Herniorrhaphy Other operations on the digestive system Breast surgery Other operations on the integumentary system Abdominal hysterectomy Other operations on the nervous system Other operations on the musculoskeletal system Knee prosthesis Gallbladder surgery Hip prosthesis Other operations on the cardiovascular system Craniotomy Open reduction of fracture Cardiac surgery Other operations on the genitourinary system Caesarean section Other operations on the eye, ear, nose, mouth and pharynx Other obstetrical operations Pacemaker surgery a

Only includes surgical procedure category with more than 250 procedures.

ward specialty categories and the corresponding consultant specialty categories. The collection of both consultant and ward specialties would appear to have little value. Less than 10% of patients in this survey had multiple system infections. In other published surveys, the proportions of patients with more than one system infection ranged from 0 to >20%.21,24e26 Factors influencing the variation between studies might include the number of patients surveyed or how rigorously the surveys were performed. It may also be in part due to the way infections were counted. For example, in this prevalence survey secondary bloodstream infections were not counted as separate infections but recorded as part of the primary infection, which may not be the case in other studies using different definitions. The prevalence of UTIs in England and NI was significantly higher than in Wales and the RoI. This may be due to the greater use of urinary catheterisation in these countries compared with the other countries and is supported by the higher

prevalence of catheter-related UTIs in England and NI when compared with the other countries. The prevalence of HCAI due to pneumonia in Wales is lower than for the other countries (Table IV). This was probably due in the main to the difficulty experienced at some hospital sites in Wales in obtaining chest x-ray results to complete the diagnosis of pneumonia. Some of these cases therefore were classified as LRTIs; this undoubtedly contributed to the differences in prevalence of LRTI in Wales compared to the other countries. The evaluation survey did not highlight a problem in obtaining chest x-ray results in the other countries. The six most prevalent system infections in order of magnitude were gastrointestinal infections, UTIs, SSIs, pneumonia, skin and soft tissue infections and primary bloodstream infections, which accounted for 86.5% of the total HCAI. With the exception of gastrointestinal infections (which is in contrast to most published surveys), this is in keeping with previous studies that found a similar basket of common system infections.16,24,25

HCAI prevalence survey: overview

245

Table IX Prevalence of Clostridium difficile healthcare-associated infection (HCAI) according to patient and hospital characteristics with odds ratios No. of patients (% patients)

Prevalence of No. of C. difficile patients HCAI with C. difficile HCAI

95% CI

Chi-squared test

Odds ratio (95% CI)

Country Overall England Northern Ireland Wales Republic of Ireland

75 694 58 775 3644 5734 7541

(100) (77.6) (4.8) (7.6) (10)

917 828 22 39 28

1.21 1.41 0.60 0.68 0.37

1.14e1.29 1.32e1.51 0.40e0.91 0.50e0.93 0.26e0.54

P < 0.001

Trust type Large acute Medium acute Acute teaching Small acute Acute specialist

23 927 19 637 16 301 6840 1448

(31.2) (25.9) (22.0) (9.0) (1.9)

299 223 239 118 10

1.25 1.14 1.47 1.73 0.69

1.12e1.40 1.00e1.29 1.29e1.66 1.44e2.06 0.38e1.27

P < 0.001

Gender Male Female

33 240 (44.0) 42 215 (56.0)

368 543

1.11 1.29

1.00e1.23 1.18e1.40

P ¼ 0.025

0.86 (0.75e0.98) 1.00

Age group (years) <35 35e64 65e84 85 <65 65

6811 (9.0) 20 308 (26.9) 34 739 (45.9) 13 526 (17.9) 27 119 48 265

15 113 506 280 128 786

0.22 0.56 1.46 2.07 0.47 1.63

0.13e0.36 0.46e0.67 1.34e1.59 1.84e2.32 0.40e0.56 1.52e1.75

P < 0.001

0.15 0.38 1.00 1.43 1.00 3.49

Consultant specialty group General medicine 44 862 (59.5) General surgery 12 677 (16.8) Trauma & orthopaedics 8877 (11.8) Obstetrics & gynaecology 4743 (6.3) Cardiothoracic surgery 1207 (1.6) Ophthalmology & ENT 1113 (1.5) Neurosurgery 962 (1.3) Critical care medicine 465 (0.6) Others 478 (0.6)

725 87 66 2 7 1 6 10 11

1.62 0.69 0.74 0.04 0.58 0.09 0.62 2.15 2.30

1.50e1.74 0.56e0.85 0.58e0.94 0.01e0.15 0.28e1.19 0.02e0.51 0.29e1.35 1.17e3.91 1.29e4.07

P < 0.001

Ward specialty group General medicine 39 885 (52.7) General surgery 13 741 (18.2) Trauma & orthopaedics 9064 (12.0) Obstetrics & gynaecology 5254 (6.9) Cardiothoracic surgery 1191 (1.6) Ophthalmology & ENT 1461 (1.9) Neurosurgery 826 (1.1) Critical care medicine 1924 (2.5) High dependency 801 (1.1) Others 1547 (2.0)

688 85 75 6 8 3 4 24 6 18

1.72 0.62 0.83 0.11 0.67 0.21 0.48 1.25 0.75 1.16

1.60e1.86 0.50e0.76 0.66e1.04 0.05e0.25 0.34e1.32 0.07e0.60 0.19e1.24 0.84e1.85 0.34e1.62 0.74e1.83

P < 0.001

ENT, ear, nose and throat; CI, confidence interval.

1.00 0.43 (0.28e0.65) 0.48 (0.35e0.66) 0.26 (0.18e0.38)

1.00 0.91 1.18 1.39 0.55

(0.76e1.08) (0.99e1.40) (1.12e1.72) (0.29e1.02)

(0.09e0.25) (0.31e0.46) (1.23e1.66) (2.90e4.21)

1.00 0.42 0.46 0.03 0.36 0.05 0.38 1.34 1.43

(0.34e0.53) (0.35e0.59) (0.01e0.09) (0.17e0.74) (0.01e0.31) (0.17e0.84) (0.72e2.49) (0.79e2.60)

1.00 0.35 0.48 0.07 0.39 0.12 0.28 0.72 0.43 0.67

(0.28e0.44) (0.37e0.60) (0.03e0.14) (0.19e0.76) (0.04e0.35) (0.11e0.72) (0.48e1.08) (0.20e0.94) (0.42e1.07)

246 Given the current preoccupation with MRSA it is interesting to note that the MRSA prevalence is 1.15% and accounts for only 15.8% of the total system infections. England has a statistically higher prevalence of MRSA infections than the other three countries (P < 0.001). The higher prevalence of MRSA infections in England is supported by mandatory reporting of MRSA bacteraemias. In Wales the rate was 0.8 per 10 000 bed-days (www.wales. nhs.uk/sites3/page.cfm?orgid ¼ 379&pid ¼ 23019) whereas in England it was 1.57 per 10 000 bed-days (www.hpa.org.uk/infections/topics_az/hai/Tables_ for_website/MRSA_sixmonthly_November_2007.xls) and in NI 1.34 per 10 000 bed-days (www.cdscni. org.uk/publications/AnnualReports/pdf/Healthcare_ Associated_Infections_report_2006.pdf). Males were more affected than females (P < 0.001; odds ratio: 1.50) and MRSA prevalence varied significantly between the age groups, being highest in those aged 65e84 years (P < 0.001). Critical care medicine and the surgical specialties (neurosurgery, cardiothoracic surgery, general surgery, and trauma and orthopaedics) accounted for the highest MRSA prevalence. When prevalence of MRSA by system infections was analysed, surgical site, skin and soft tissue infections and primary bloodstream were the most frequent. The prevalence of MRSA by system infections by country shows a significant difference between the countries only for SSIs and skin and soft tissue infections (P ¼ 0.001 and P < 0.001 respectively). The highest prevalence of SSIs occurred in the procedure categories limb amputation, peripheral vascular bypass surgery small bowel surgery, abdominal surgery, and colon surgery. These categories also coincided with the highest prevalence of MRSA infection. The hospital-associated C. difficile prevalence in England was significantly higher than in the other three countries (P < 0.001). Patients aged >65 years had a higher hospital-associated C. difficile prevalence than those aged <65 years. Hospitalassociated C. difficile infection prevalence was highest in critical care medical units. Almost 80% (725/917) of the patients with hospital-associated C. difficile infections were in patients under the general medical consultant specialty category that included the specialty usually referred to as ‘care of the elderly’. Fourteen percent of those with hospital-associated C. difficile infections were patients aged <65 years. A possible explanation for the high prevalence of gastrointestinal infections in English hospitals might be due to the high prevalence of C. difficile in England compared with the other countries in this survey. The mandatory reporting for C. difficile in England for 2006

E.T.M. Smyth et al. show the rate in those aged 65 was 2.38 per 1000 bed-days (www.hpa.org.uk/infections/topics_ az/hai/Tables_for_website/Cdiff_annually_Nov_ 2007.xls). In NI, the rate was 1.04 per 1000 beddays in those aged 65 years (www.cdscni.org. uk/publications/AnnualReports/pdf/Healthcare_ Associated_Infections_report_2006.pdf). However, the reports for England and NI did not distinguish between hospital-associated and community (or otherwise)-associated C. difficile infection. Comparable data are not available for Wales as their rates were published per 1000 admissions. C. difficile infection is not notifiable in the RoI, therefore national data were not available.

Validation In England the adjustment to the crude prevalence is only minor (8.19%e7.85% ¼ 0.34%) indicating that the prevalence would only have been marginally different if the patients had been assessed by those performing the validation rather than hospital staff. The agreement for the validation series was perfect in the NI series e partly no doubt because there is less scope for disagreements on a much smaller series. Both the crude prevalence estimate for Wales (6.35%), with its CI, and the adjusted estimate, with its CI, were valid, but were based on different assumptions. The crude estimate disregards the validation results; the adjusted estimate disregards the result reported by hospital staff. These two scenarios represent two extremes, and were reported as a kind of sensitivity analysis. Reality is likely to be intermediate between them, with rather greater credence given to results reported by the WHAIP team as validators. Feedback from the evaluation at the completion of the survey indicated that a majority of hospitals surveyed more beds rather than the minimum number they were allocated. We feel that two factors contributed to the large number of patients surveyed; first, information relating to HCAI was seen by Trusts/hospitals as important; second, the ease of data collection made the survey less unwieldy than the previous national prevalence surveys. The vast majority of respondents were satisfied with the survey questionnaire and most had a positive attitude to participating in future surveys. Overall, participants were content with the layout of the survey form, the protocol/manual, and CDC definitions, with the pneumonia definitions being considered to be the most difficult to apply. In addition, for many, participation in the survey was useful in identifying problems with medical, nursing and device-related documentation.

HCAI prevalence survey: overview

Conclusions The overall prevalence of HCAI in the four countries was 7.59%. Efforts should be made to concentrate resources in the areas where interventions are known to be beneficial. Many infections were associated with device usage and should present an opportunity to embrace the care-bundle approach of patient safety campaigns to address device management, e.g. care bundles for urinary catheter, peripheral line, ventilator, SSI and CVC management care bundles. Although this study did not concentrate on antimicrobial prescription, sufficient evidence has emerged to further support those efforts regarding prudent antimicrobial prescribing. The results of this survey vindicate the time and effort spent on the design, preparation and training. The validation results demonstrate the commitment and dedication of the data collectors to the application of the survey methodology and definitions of infection. This was the largest HCAI prevalence survey ever performed in the four countries. The methodology and organisation employed should be used as a template for future HCAI surveillance initiatives, nationally, locally or at unit level. This survey has provided a baseline against which future surveys can be compared and to enable the monitoring of progress over time. In the absence of targeted incidence surveillance, we recommend consideration of repeat prevalence surveys as an effective means of measuring the impact of interventions over time. Information obtained from this survey will contribute to the prioritisation of resources and help to inform Departments of Health, hospitals and other relevant bodies in the continuing effort to reduce HCAI.

Acknowledgements This survey would not have been completed successfully and within schedule without the co-operation and support of the co-ordinators, microbiologists, IPCTs and other staff within the participating hospitals. We would like to acknowledge the assistance given by the HIS and ICNA members who helped with the training of the participants. We would also acknowledge the assistance and support of the members of WHAIP, HISC and HPSC who contributed to the success of the prevalence survey. In addition, we would like to thank the other members of the HCAI Prevalence Survey Steering Group: R. Cunney, B. Duerden, A. Fraise, C. Fry, M. Greig, T. Howard,

247 M. Kiernan, C. Perry, J. Reilly, J. Richards, G. Ridgway and M. Simmons. Dedication The authors would like to dedicate this paper to the memory of professor A.M. (Mike) Emmerson OBE (1937e2008). Conflict of interest statement None declared. Funding sources This work has been supported by grants from Department of Health, England; Department of Health Social Services & Public Safety, Northern Ireland; Welsh Assembly Government, Wales; Health Service Executive, Republic of Ireland.

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