This article appears in the following Journal of Antimicrobial Chemotherapy issue: Aspects of Antimicrobial Resistance [View the issue table of contents]
Articles |
Voluntary and mandatory surveillance for methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) bacteraemia in England
Health Protection Agency, Centre for Infections, 61 Colindale Avenue, London NW9 5EQ, UK
* Corresponding author. Tel: +44-208-327-7333; Fax: +44-208-205-9185; E-mail: andrew.pearson{at}hpa.org.uk
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Abstract |
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 Top Abstract IntroductionTrends in reporting of...DiscussionFundingTransparency declarationsReferences |
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Voluntary laboratory reporting of communicable disease, including bacteraemia, has been the mainstay of surveillance in England for >30 years. The impact of introducing a parallel mandatory reporting process for surveillance of Staphylococcus aureus bacteraemia [both methicillin susceptible (MSSA) and resistant (MRSA)] was assessed by national and regional comparison of MSSA and MRSA reports to the two surveillance systems. Introduction of mandatory reporting in 2001 demonstrated that the true number of cases was 40% higher than indicated by voluntary reporting (i.e. 60% case ascertainment by voluntary reporting). However by 2008 the difference in reporting of MRSA bacteraemia between the two systems dropped to 30%, with six of the nine health regions in England having improved their levels of voluntary reporting, although there was still under-reporting from London, the South East and the North West. Improvements in voluntary surveillance contributed to increased ascertainment of bacteraemia due to S. aureus (both MRSA and MSSA). Decreasing trends for MRSA bacteraemia were evident in both surveillance systems, with a 56% decrease in the mandatory and a 53% decline in the voluntary systems, from 2004. In contrast there was little change in reported cases of MSSA during 2004–2006. However, in 2007, when MRSA bacteraemia case numbers decreased by 27%, MSSA bacteraemia case reports actually increased by 6%. Trends for MSSA bacteraemia can be assessed more accurately from voluntary than from mandatory surveillance at the present time because mandatory reporting of MSSA bacteraemia is incomplete, with only 133 of 170 (78%) Trusts reporting in all four quarters of a year.
Keywords: nosocomial infection , Staphylococcus aureus , MSSA trends
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Introduction |
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TopAbstractIntroductionTrends in reporting of...DiscussionFundingTransparency declarationsReferences |
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Reporting of cases of bacteraemia by hospital microbiologists to the UK HPA, together with notifications of infectious diseases, has provided the foundation of communicable disease surveillance in England, Wales and Northern Ireland for the past 30 years. With specific regard to surveillance of bacteraemia due to methicillin-resistant or -susceptible Staphylococcus aureus (MRSA and MSSA) in England, data from hospital microbiology laboratories are now collected via dual reporting systems, one voluntary and one mandated by the Government (Figure 1).1 This review describes the national and regional impact of the introduction of mandatory surveillance by comparing the mandatory and voluntary reporting of MRSA and MSSA bacteraemia during the period 2002–2008.
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Voluntary reporting of bacteraemia due to S. aureus
The voluntary reporting scheme, based on reports from hospital laboratories, collects data on bacteraemia from England, Wales and Northern Ireland, although data from the latter two countries will not be considered further in this article. The HPA voluntary surveillance system initially collected paper reports but now comprises a reporting module (CoSurv) consisting of a set of database modules for recording both laboratory isolates and case notifications. Separate modules currently exist for hospital laboratories, Health Protection Units/Local Authorities and Regional Units of the HPA. Isolate reports fed into the laboratory module of CoSurv are electronically transferred to the regional CoSurv module (at the HPA regional unit) and to the District CoSurv Module at Health Protection Units (HPUs) or Local Authorities (Figure 2). The reports collected at regional level are then relayed to LabBase, the national database held at the Centre for Infections (CfI) in Colindale, London. The development of CoSurv and LabBase is shown in Tables 1 and 2.
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Mandatory reporting of bacteraemia due to S. aureus
In an attempt to improve the level of reporting of bacteraemia due to MRSA and MSSA, the Department of Health (DH) in England made it mandatory for acute National Health Service (NHS) Trusts to report all cases of S. aureus bacteraemia, and to report the number due to MRSA.2 This surveillance programme commenced in April 2001, with the resulting data for 6 or 12 month periods being published on the HPA web site.3 Initially the data were submitted to the HPA in a range of formats, but from 2005 reporting has been enhanced and reported via a web-enabled reporting system (Figure 1).4,5 Also, since 2005, there has been a requirement for data from each Trust to be signed off by the Trust's Chief Executive.
Comparison of the voluntary and mandatory surveillance schemes
Differences between the definitions of MRSA bacteraemia in the mandatory and voluntary reporting systems mean that direct comparisons, based on absolute counts, need to be qualified to reflect the differences in definition and resulting ascertainment. In the voluntary scheme, clinically significant bacteraemias are reported, and for individual cases, a 14 day exclusion rule is applied in LabBase, subject to patient identifiers being available that allow identification of successive positive blood cultures from the same patient. In contrast, in the mandatory reporting system, all blood cultures positive for MRSA, whether clinically significant or not, whether treated or not and whether acquired in the Trust or elsewhere, must be reported. Positive blood cultures from the same patient within 1 day of the initial culture are considered to be part of the original episode and are not reported. All other laboratory reports (e.g. contaminants, work undertaken for the non-acute sector of the NHS and bacteraemia cases detected prior to admission) are required to be recorded.
One of the quality control checks of the mandatory reporting scheme is cross-checking the mandatory surveillance returns from each Trust against the corresponding laboratory electronic data capture system 6–8 weeks after the sign-off of the mandatory return. This frequently identifies small numbers of cases (often fewer than five) which have been reported voluntarily but do not appear in the mandatory data set. Such discrepancies are investigated and normally explained by the case not being due to MRSA upon retesting (e.g. MSSA) or the sample being erroneously entered as a blood culture. These cases are subsequently updated on LabBase.
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Trends in reporting of bacteraemia due to MRSA and MSSA as determined by voluntary and mandatory reporting |
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TopAbstractIntroductionTrends in reporting of...DiscussionFundingTransparency declarationsReferences |
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Analysis of voluntary reports of S. aureus bacteraemia in England and Wales showed a dramatic year on year increase in the proportion of isolates that were resistant to methicillin during the 1990s, rising from 2% in 1990 and 1991 to a peak of 43% in 2002, with a slight decline thereafter.1 This is reflected by the increase in reports of MRSA bacteraemia seen during this time (Figure 3).
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The corresponding trends in annual total numbers of MRSA bacteraemia cases reported in the voluntary and mandatory surveillance schemes since 2001–02 are depicted in Figures 3
–5. Figure 3 indicates that the introduction of mandatory reporting in 2001 resulted in a marked increase in ascertainment of cases of MRSA bacteraemia, the number of cases reported via the mandatory scheme being 40% above the number recorded through voluntary reporting (i.e. case ascertainment by voluntary reporting was 60% of that achieved by the Government mandate). However, by 2008, the difference in reporting between the mandatory and voluntary systems had reduced to 30%. This was due mainly to improvements in the data transfer from laboratories to LabBase, an inference supported by analysis of regional reporting, where this 30% difference in case ascertainment was due to reporting variation predominantly in three health regions, namely London, the South East and the North West (Figures 6 and 7).
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Figures 3
–5 clearly illustrate the decreasing trend for MRSA bacteraemia as evidenced by the reduced numbers of MRSA cases recorded in both surveillance systems: the mandatory data set showed a 56% reduction in MRSA bacteraemia between 2004 and 2008 as compared with a 53% reduction in MRSA bacteraemia cases reported by the voluntary system. Interestingly, comparison of mandatory and voluntary surveillance bacteraemia indicated that the downward trends noted with total S. aureus and MRSA bacteraemia were not apparent with bacteraemia due to MSSA. Analysis of MSSA bacteraemia from the national voluntary system indicates little change in reported cases during 2004–2006, with 7957, 7973 and 8089 cases, respectively. In 2007, MSSA bacteraemia case reports actually increased by 6% to 8584, at the time when MRSA bacteraemia case numbers reduced by 27% (Figure 4). The reason that the mandatory surveillance figures for MSSA bacteraemia appear to show a different trend from that seen with voluntary surveillance is that at the present time the requirement for Trusts to make mandatory returns for MSSA bacteraemia is complied with for all four quarters of each year by only three-quarters of Trusts (Figure 5). This level of under-reporting in the last 2 years precludes valid interpretation of trends for MSSA bacteraemia and total S. aureus.
Reports from each of the nine English health regions followed the trend in the decline in the number of MRSA bacteraemia cases from 2003. A general improvement in the reporting of MRSA bacteraemia to the national voluntary laboratory reporting system is seen in Figures 6 and 7. Figure 6 shows the ratio of mandatory to voluntary reports (1 indicates an equal number of voluntary and mandatory reports) over time and, as can be seen, London in particular under-reported the number of cases via the voluntary surveillance scheme, with 3672 cases reported during 2002–2008 compared with 8960 via mandatory surveillance. However this ratio decreased in recent years (Figure 7). The North West shows a similar pattern. The East of England and the East and West Midlands have ratios very close to 1 (1.05, 1.34 and 1.07, respectively), and thus reported similar numbers of cases via both voluntary and mandatory surveillance.
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Discussion |
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TopAbstractIntroductionTrends in reporting of...DiscussionFundingTransparency declarationsReferences |
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The Government mandate requiring NHS hospitals in England to report MRSA bacteraemia and total S. aureus (enabling deduction of MSSA) was used to enable accurate and timely measurement of the impact of an inspirational national public health initiative to reduce MRSA bacteraemia by 50%. This Government-led intervention resulted from relentless public and political pressure arising from the increasing mortality associated with the marked rise during the 1990s in the numbers of cases of S. aureus bacteraemia and an increase in the proportion of such cases that were MRSA.
Introduction of mandatory reporting was effected in stages, the last step being in 2005 with the provision of an interactive web-enabled reporting system that was to run in parallel with the routine voluntary laboratory systems used for monitoring communicable disease in England. Running these two reporting systems in parallel demonstrated that in 2004 the voluntary system had an ascertainment rate of 60%, although this increased to 70% by 2008. The regional analyses depicted in this review indicate that the majority of under-reporting of S. aureus now resides with just three of the nine English health regions. Conversely the trends seen in the other six health regions now show mandatory and voluntary data that closely reflect the high degree of ascertainment now realized by mandatory reporting of S. aureus.
The decreasing trends achieved for MRSA bacteraemia were seen in both surveillance systems, demonstrating the increasing reliability of national voluntary laboratory reporting for surveillance of S. aureus.
These findings indicate the importance of using dual reporting systems to allow comparison and assessment to be made as to the potentially differential impact on the accuracy of mandatory data for MSSA bacteraemia that may have resulted from restricting the performance management process to reducing only MRSA (rather than MRSA as a component of all S. aureus).
These findings indicate the importance of using dual reporting systems that may both improve ascertainment when mandatory reporting is subject to performance management but may lead to under-ascertainment if scrutiny and quality control vary between the different causes of healthcare-acquired infection.
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Funding |
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Work reported here was undertaken as part of the core HPA/DH programme of deliverables for the national surveillance of healthcare-associated infections.
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Transparency declarations |
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None to declare.
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Acknowledgements |
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We thank all laboratories who have contributed data to the surveillance scheme, and colleagues within the HPA Local and Regional Services and Centre for Infections. We would also like to thank Dr Michael Painter, the HPA Medical Illustration Department and the mandatory surveillance and LabBase teams at the HPA Centre for Infections.
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References |
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1 Johnson AP, Duckworth G, Pearson A. Surveillance and epidemiology of MRSA bacteraemia in the UK. J Antimicrob Chemother (2005) 56:455–62.
2 Department of Health. Surveillance of healthcare associated infections. CMO's Update 30. May 2001. http://www.dh.gov.uk/assetRoot/04/01/36/52/04013652.pdf (15 June 2009, date last accessed).
3 Health Protection Agency. Quarterly results from the mandatory surveillance of MRSA. Bacteraemia. http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1233906819629 (15 June 2009, date last accessed).
4 Department of Health. Mandatory surveillance of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemias. http://www.dh.gov.uk/assetRoot/04/11/25/90/04112590.pdf (15 June 2009, date last accessed).
5 Department of Health. Reporting MRSA data: overview of arrangements, including (i) new schedules for data submissions (ii) overview of responsibilities: data checks. http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@dh/@en/documents/digitalasset/dh_4132875.pdf (15 June 2009, date last accessed).
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