Core Topics in General & Emergency Surgery: Companion to Specialist Surgical Practice (4 page)
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Authors: Simon Paterson-Brown MBBS MPhil MS FRCS
Once a question has been formulated, the next step in undertaking EBM is the identification of all the relevant evidence. The first line for most practitioners is the use of journals. Many clinicians will subscribe to specific journals in their own specialist area and have access to many others through local libraries. However, the vast increase in the number of such publications makes it impossible for an individual to access or read all the relevant papers, even in a highly specialist area.
There has been a huge expansion in the resources that are available for identifying relevant material from other publications, including indexing and abstracting services such as MEDLINE (computerised database compiled by the US National Library of Medicine) and EMBASE. There is also a rapidly expanding set of journals and other services that provide access to selected, appraised and combined results from primary information sources.
As a result, the information sources that provide the evidence to support EBM are vast and include the following:
Media – journals, online databases, CD-ROMs and the Internet.
Independent organisations – research bodies and the pharmaceutical industry.
Health services – purchasers and providers at local, regional and national levels.
Academic units.
Some of these are described in more detail below and the Appendix to this chapter provides a list of contact details for further information.
The following are a selection of journals that act as secondary sources, identifying and reviewing other research that is felt to be of key importance to evidence-based practice.
This was first launched in October 1995, by the
British Medical Journal
(BMJ) Publishing Group. It systematically searches high-quality international journals and provides summaries of the most clinically relevant research articles. The validity of the research is critically appraised by experts and assessed for its clinical applicability. This consequently allows the reader to keep up with the latest advances in clinical practice. It also publishes articles relating to the study and practice of EBM.
This follows similar lines to
Evidence-based Medicine
, but contains articles more relevant to the nursing field.
This is produced by the BMJ Publishing Group in collaboration with the Royal College of Psychiatrists and British Pyschological Society.
The Internet is becoming an increasingly useful source of medical information and evidence. Details of Internet addresses for many of the sources referred to below are given in the Appendix to this chapter, although this is a rapidly progressing and changing area. There are many journals and databases that are available either free or through subscription, and dedicated search engines such as Google Scholar. This medium also provides a number of advantages over printed material, including ease of searching, hyperlinks to other sources, access to additional supporting materials or raw data and the provision of discussion groups. There are, however, potential problems with the Internet in that there is no quality control and much of the available material is of dubious quality, or published by those with particular commercial or other interests.
This is a new service that provides online access to evidence-based information. It is managed by NICE and is free to use. It has access to NICE pathways, journals and databases, ebooks and the Cochrane library.
This provides information, resources and tools that aid evidence-based practice. It has access to sites that target EBM in relation to patient care, research and patient information, and has updates on current evidence and treatment options.
Cochrane Collaboration
As described above, the British epidemiologist who inspired this collaboration realised that in order to make informed decisions about healthcare, reliable evidence must be accessible and kept up to date with any new evidence. It was felt that failure to achieve this might result in important developments in healthcare being overlooked. This was to be a key aspect in providing the best healthcare possible for patients. It was also hoped that by making clear the result of an intervention, then work would not be duplicated.
The Cochrane library is the electronic publication of the Cochrane Collaboration and it includes six databases:
The Cochrane Database of Systematic Reviews contains systematic reviews and protocols of reviews in preparation. These are regularly updated and there are facilities for comments and criticisms along with authors' responses.
The Cochrane Central Register of Controlled Trials is the largest database of RCTs. Information about trials is obtained from several sources including searches of other databases and hand searching of medical journals. It includes many RCTs not currently listed in databases such as MEDLINE or EMBASE.
The Database of Abstracts of Reviews of Effectiveness (DARE) contains abstracts of reviews that have been critically appraised by peer reviewers. These reviews evaluate the effects of healthcare interventions and the delivery and organisations of health services.
The Cochrane Review Methodology Register is a bibliography of articles on the science of research synthesis.
Health Technology Assessment Database (HTA) – see below.
NHS Economic Evaluation Database (NHS EED) – see below.
The Reviewers' Handbook includes information on the science of reviewing research and details of the review groups. It is also available in hard copy.
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The Cochrane library is regularly updated and amended as new evidence is acquired. It is distributed on disk, CD-ROM and the Internet.
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In order to allow the results of the reviews to be widely used, no one contributor has exclusive copyright of the review.
The Centre for Evidence-based Medicine was established in Oxford. Its chief remit is to promote EBM and Evidence-Based Practice (EBP) in healthcare. It runs workshops and courses in both the practice and teaching of EBM. It also conducts research and development on improving EBP and its website also has many free EBM resources and tools.
This is a joint venture between the Health Services Research Unit at Sheffield University and Aberdeen University. It works under the auspices of NICE's Interventional Procedures Programme (IPP). When there is doubt about the safety and efficacy of any procedure they will be commissioned to provide a systematic review or gather additional data.
Centre for Reviews and Dissemination (CRD)
The CRD was established in January 1994 at the University of York and is now also part of the National Institute for Health Research (NIHR). It is funded by NIHR England, the Department of Health, Public Health Agency, Northern Ireland, and the National Institute for Social Care and Health Research, Welsh Assembly Government. The CRD concentrates specifically on areas of priority to the NHS. It is designed to raise the standards of reviews within the NHS and to encourage research by working with healthcare professionals. It undertakes and disseminates systematic reviews and maintains three databases:
NHS EED contains mainly abstracts of economic evaluations of healthcare interventions and assesses the quality of the studies, stating any practical implications to the NHS.
DARE (see above).
The Health Technology Assessment (HTA) database details completed and ongoing HTAs from around the world. The contents of this database have not been critically appraised.
The HTA is now part of National Institute for Health Research (NIHR). It commissions independent research into high-priority areas. This includes many systematic reviews and primary research in key areas. The programme publishes details of ongoing HTA projects and monographs of completed research.
This is the process by which we assess the evidence presented to us in a paper. We need to be critical of it in terms of its validity and clinical applicability.
From reading the literature, it is evident that there may be many trials on the same subject, which may all draw different conclusions. Which one should be believed and allowed to influence clinical practice? We owe a duty to our patients to be able to assess accurately all the available information and judge each paper on its own merits before changing our clinical practice accordingly.
The RCT is a comparative evaluation in which the interventions being compared are allocated to the units being studied purely by chance. It is the ‘gold standard’ method of comparing the effectiveness of different interventions.
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Randomisation is the only way to allow valid inferences of cause and effect,
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and no other study design can potentially protect as well against bias.
Unfortunately, not all clinical trials are done well, and even fewer are well reported. Their results may therefore be confusing and misleading, and it is necessary to consider several elements of a trial's design, conduct and conclusions before accepting the results. The first requirement is that there must be sufficient detail available to make such an assessment.
It became clear that there was a need for the presentation of clinical trials to be standardised. The CONSORT (Consolidated Standards of Reporting Trials) statement was developed. The most recent version is CONSORT 2010 (
Table 1.1
).
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,
18
The CONSORT 2010 statement lists 25 items that should be included in any trial report, along with a flow chart.
17,
18
Table 1.1
CONSORT 2010 checklist of information to include when reporting a randomised trial
*
*
We strongly recommend reading this statement in conjunction with the CONSORT 2010 Explanation and Elaboration for important clarifications on all the items. If relevant, we also recommend reading CONSORT extensions for cluster randomised trials, non-inferiority and equivalence trials, non-pharmacological treatments, herbal interventions, and pragmatic trials. Additional extensions are forthcoming: for those and for up-to-date references relevant to this checklist, see
www.consort-statement.org
.
Reproduced from Schulz KF, Altman DG, Moher D et al. Br Med J 2010; 340:c332 and Moher D, Hopewell S, Schulz KF et al. Br Med J 2010;340:c869. With permission from the BMJ Publishing Group Ltd.
Many journals now encourage authors to submit a copy of the CONSORT statement relating to their paper. A similar checklist has been proposed for the reporting of observational studies (cohort, case–control and cross-sectional). This is called the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement.
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The QUORUM statement is a similar checklist that has been developed to improve the quality of reporting relating to systematic reviews of RCTs.
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The STROBE statement provides a recommended checklist for the reporting of observational studies
19
and the QUORUM statement provides similar recommendations for systematic reviews of RCTs.
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The Critical Appraisal Skills Programme (CASP) is a UK-based project designed to develop appraisal skills about effectiveness. It provides half-day workshops and has developed appraisal frameworks based on 10 or 11 questions for RCTs, qualitative research and systematic reviews.
Assuming that the relevant information is available, critical appraisal is required to ensure that the methodology of the trial is such that it will minimise effects on outcome other than true treatment effects, i.e. those owing to
chance
,
bias
and
confounding
:
Chance – random variation, leading to imprecision.
Bias – systematic variation leading to inaccuracy.
Confounding – systematic variation resulting from the existence of extraneous factors that affect the outcome and have distributions that are not taken into account, leading to bias and invalid inferences.
All good study designs will reduce the effects of chance, eliminate bias and take confounding into account. This requires consideration of many aspects of trial design, including methods of randomisation, blinding and masking, analysis methods and sample size. It also requires the reviewer to consider aspects such as sponsorship and vested interests that may introduce sources of bias. Discussion of methodology for the critical appraisal of RCTs and other forms of study is readily available elsewhere.
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