Universal screening for meticillin-resistant Staphylococcus aureus: interim results from the NHS Scotland pathfinder project

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Summary

Following recommendations from a Health Technology Assessment (HTA), a prospective cohort study of meticillin-resistant Staphylococcus aureus (MRSA) screening of all admissions (N = 29 690) to six acute hospitals in three regions in Scotland indicated that 7.5% of patients were colonised on admission to hospital. Factors associated with colonisation included re-admission, specialty of admission (highest in nephrology, care of the elderly, dermatology and vascular surgery), increasing age, and the source of admission (care home or other hospital). Three percent of all those who were identified as colonised developed hospital-associated MRSA infection, compared with only 0.1% of those not colonised. Specialties with a high rate of colonisation on admission also had higher rates of MRSA infection. Very few patients refused screening (11 patients, 0.03%) or had treatment deferred (14 patients, 0.05%). Several organisational issues were identified, including difficulties in achieving complete uptake of screening (88%) or decolonisation (41%); the latter was largely due to short duration of stay and turnaround time for test results. Patient movement resulted in a decision to decolonise all positive patients rather than just those in high risk specialties as proposed by the HTA. Issues also included a lack of isolation facilities to manage patients with MRSA. The study raises significant concerns about the contribution of decolonisation to reducing risks in hospital due to short duration of stay, and reinforces the central role of infection control precautions. Further study is required before the HTA model can be re-run and conclusions redrawn on the cost and clinical effectiveness of universal MRSA screening.

Introduction

Meticillin-resistant Staphylococcus aureus (MRSA) infections are associated with greater risk of treatment failure, increased patient mortality and higher costs than infections with meticillin-susceptible S. aureus.1, 2 Within Europe, countries with low endemicity are observing an increase in the proportion of S. aureus cases due to MRSA; Scotland and the rest of the UK continue to have relatively high rates of MRSA, in common with Mediterranean countries, Romania and Ireland.3 MRSA is a particular challenge in hospitals as patients with wounds, invasive devices and weakened immune systems are at greater risk of infection than the general public.4

Uncertainty remains over the effectiveness of any single control measure compared with another, as they do not act independently and are often implemented concurrently. The Society for Healthcare Epidemiology of America guidelines have noted that multiple studies implementing surveillance, screening and contact precautions have resulted in a significant reduction in the rates of both MRSA colonisation and infection.5, 6 Screening identifies patients who are either colonised or infected, which allows targeted intervention to reduce the risk of endogenous infection and transmission to others.

Universal screening of all patients for MRSA continues to be controversial.7, 8 The most recent UK professional guidance on MRSA promotes targeted screening, but this has not been implemented in a consistent manner.9 Current MRSA screening practice within Scotland is locally determined, and is generally targeted on the basis of the perceived likelihood of MRSA carriage and risk of infection.

Policy proposals for universal MRSA screening of hospital patients have recently been developed in UK countries.10, 11, 12, 13, 14 This process in Scotland followed the publication of the National Health Service (NHS) Quality Improvement Scotland Health Technology Assessment (HTA) on the clinical- and cost-effectiveness of MRSA screening.15 An MRSA screening pilot study in Scotland was developed from the HTA recommendations, using the UK National Screening Committee screening criteria as a framework. These interim results present the findings from the first five months of data collection.

Section snippets

Methods

This was a prospective cohort study in six hospitals in three regions (NHS Ayrshire and Arran, NHS Grampian and NHS Western Isles Health Board areas) in Scotland.

Participating hospitals followed the strategy recommended by the HTA which, of the six possible strategies investigated, was judged the most cost-effective and clinically effective approach.15 This strategy specified: screening all overnight admissions in acute specialties (excluding obstetrics, psychiatry and paediatrics); isolating

Results

The demographics of patients from the six hospitals (N = 29 690) inclusive of 15 081 admissions from Grampian Health Board, 13 700 from Ayrshire and Arran and 909 from Western Isles are presented in Table I.

The overall prevalence of MRSA colonisation during the study period was 7.47%, representing the burden of patients requiring intervention at any given point in time. Table II shows that 26 160 patients (88.1% of total hospital admissions) were screened either at pre-admission clinics or on

Discussion

This is the first UK pilot study for a national MRSA screening programme. The total prevalence of MRSA colonisation at time of admission was found to be 7.5%. The percentage of patients identified as colonised by screening was 3.8% but, in addition, 5.9% of admissions (screened or not) were known previous MRSA positives. Prevalence of MRSA colonisation is defined in different ways in the published literature, which makes comparisons difficult but highlights the need for consistency.1, 8, 16

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    The full report was published on the Health Protection Scotland website on 8 April 2008: www.hps.scot.nhs.uk.ISBN 978-1-873772-27-0.

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