HOSPITAL SERVICES MANAGEMENT
EVIDENCE BASED PRACTICE
Updated: 29th November'2011
Evidence Based Medicine
What is Evidence Based Medicine?
Evidence-based medicine (EBM) is the integration of best research evidence with clinical expertise and patient values.
· By best research evidence we mean clinically relevant research, often from the basic sciences of medicine, but especially from patient centered clinical research into the accuracy and precision of diagnostic tests (including the clinical examination), the power of prognostic markers, and the efficacy and safety of therapeutic, rehabilitative, and preventive regimens. New evidence from clinical research both invalidates previously accepted diagnostic tests and treatments and replaces them with new ones that are more powerful, more accurate, more efficacious, and safer.
· By clinical expertise we mean the ability to use our clinical skills and past experience to rapidly identify each patient’s unique health state and diagnosis, their individual risks and benefits of potential interventions, and their personal values and expectations.
· By patient values we mean the unique preferences, concerns and expectations each patient brings to a clinical encounter and which must be integrated into clinical decisions if they are to serve the patient.
Why the sudden interest in EBM?
These ideas have been around for a long time. The expression in post-revolutionary Paris (when clinicians like Pierre Louis rejected the pronouncements of authorities* and sought the truth in systematic observation of patients), and a colleague has nominated a much earlier origin in ancient Chinese medicine†. In the current era, they were consolidated and named EBM in 1992 by a group led by Gordon Guyatt at McMaster University in Canada. Since then, the number of articles about evidence-based practice has grown exponentially (from 1 publication in 1992 to about a thousand in 1998) and international interest has led to the development of 6 evidence-based journals (published in up to 6 languages) that summarize the most relevant studies for clinical practice and have a combined world-wide circulation of over 175,000.
The subsequent rapid spread of EBM has arisen from 4 realizations and is made possible by 5 recent developments. The realizations, attested to by ever-increasing numbers of clinicians, are:
Until recently, these problems were insurmountable for full-time clinicians. However, 5 developments have permitted us to turn this state of affairs around:
1. The development of strategies for efficiently tracking down and appraising evidence (for its validity and relevance).
2. The creation of systematic reviews and concise summaries of the effects of health care (epitomized by the Cochrane Collaboration).
3. The creation of evidence-based journals of secondary publication (that publish the 2% of clinical articles that are both valid and of immediate clinical use‡).
4. The creation of information systems for bringing the foregoing to us in seconds.
5. The identification and application of effective strategies for life-long learning and for improving our clinical performance.
How do we actually practice EBM?
The full-blown practice of EBM comprises 5 steps,
· Step 1: Converting the need for information (about prevention, diagnosis, prognosis, therapy, causation, etc) into an answerable question .
· Step 2: Tracking down the best evidence with which to answer that question .
· Step 3: Critically appraising that evidence for its validity (closeness to the truth), impact (size of the effect), and applicability (usefulness in our clinical practice)
· Step 4: Integrating the critical appraisal with our clinical expertise and with our patient’s unique biology, values and circumstances
· Step 5: Evaluating our effectiveness and efficiency in executing Steps 1-4 and seeking ways to improve them both for next time
When we examine our practice and that of our colleagues and trainees in this 5-step fashion, we can identify 3 different “modes” or “styles” of practice. All of them involve the integration of evidence (from whatever source) with our patient’s unique biology, values and circumstances of Step 4, but they vary in the execution of the other steps.
For the conditions we encounter every day (e.g., unstable angina and venous thromboembolism) we need to be “up-to-the-minute” and very sure about what we are doing. Accordingly, we invest the time and effort necessary to carry out both steps 2 (searching) and 3 (critically appraising), and operate in the “appraising” mode; all the chapters in this book are relevant to the “appraising” mode.
For the conditions we encounter less often (e.g., temporal arteritis, aspirin poisoning), we conserve our time by seeking out critical appraisals already performed by others who describe (and stick to!) explicit criteria for deciding what evidence they selected and how they decided whether it was valid. That is, we leave out the time-consuming Step 3 (critically appraising) and carry out just Step 2 (searching) but restrict the latter to
sources that have already undergone rigorous critical appraisal (Cochrane Reviews, Best Evidence, and the like).
Only the third portions (“Can I apply this valid, important evidence to my patient?”) are strictly relevant here, and the growing database of pre-appraised resources is making this “searching” mode more and more feasible for busy clinicians. The reassuring thing about practicing in either the “appraising” or “searching” modes is that we can be pretty sure that we are providing “evidence-based care” to our patients.
This reassurance is lacking from the third mode of practice. For the problems we’re likely to encounter very infrequently (the last example from the Sackett/Straus service was a man who developed bad pneumonia while trying to reject his heart-lung transplant), we “blindly” seek, accept and apply the recommendations
Can clinicians actually practice EBM?
First of all, do full-time clinicians really recognize working in these modes? It appears so.
In a survey of UK GPs (in which responders were more likely to hold MRCP certification), the great majority reported practicing at least part of their time in the “searching” mode, using evidence- based summaries generated by others (72%) and evidence-based practice guidelines or protocols (84%)
On the other hand, far fewer claimed to understand (and be able to explain) the “appraising” tools of NNTs (35%) and confidence intervals (20%). Finally only 5% believed that “learning the skills of evidence-based medicine” (all five steps) was the most appropriate method for “moving from opinion-based medicine to evidence-based medicine.
Second, even if they recognize these modes, can they actually get at the evidence quickly enough to consider it on a busy clinical service? Again, it appears so, but examples are few. When a busy (180+ admissions per month) in-patient medical service brought electronic summaries of evidence previously appraised either by team members (“CATs”††) or by the summary journals to working rounds, it was documented that, on average, the former could be accessed in 10 seconds and the latter in 25.
Moreover, when assessed from the viewpoint of the most junior member of the team caring for the patient, this evidence changed 25% of their diagnostic and treatment suggestions and added to a further 23% of them.
Third, even if they can get at it, can clinicians actually provide evidence-based care to their patients? Again, it appears so from audits carried out on clinical services that attempt to operate in the searching and appraising modes. The first of these examined the evidence-base for the primary interventions applied to the primary diagnoses of consecutive patients on an in-patient medical service and documented that 82% of them were evidence-based (53% based on randomized trials or systematic reviews of randomized trials and 29% based on convincing non-experimental evidence). Similar results have been obtained from audits of psychiatric, surgical, pediatric and general practice.
Does providing evidence-based care improve outcomes for patients?
No such evidence is available from randomized trials because no investigative team or research granting agency has yet overcome the problems of sample-size, contamination, blinding, and long-term follow-up which such a trial requires. Moreover, there are ethical concerns with such a trial: is withholding access to evidence from the control clinicians ethical?
On the other hand, population-based “outcomes research” has repeatedly documented that those patients who do receive evidence-based therapies have better outcomes than those who don’t. For positive examples, myocardial infarction survivors prescribed aspirin or beta blockers have lower mortality rates than those who aren’t prescribed these drugs, and where clinicians use more warfarin and stroke unit referrals, stroke mortality declines by >20%.23 For a negative example, patients undergoing carotid surgery despite failing to meet evidence-based operative criteria, when compared with operated patients who meet those criteria, are more than 3 times as likely to suffer major stroke or death in the next month
What are the limitations of EBM?
The examination of the concepts and practice of EBM by clinicians and academics has led to negative as well as positive reactions. The ensuing discussion and debate has reminded us of 3 limitations that are universal to science (whether basic or applied) and medicine (the shortage of coherent, consistent scientific evidence; difficulties in applying any evidence to the care of individual patients; barriers to any practice of high quality medicine). The debate has also identified 3 limitations that are unique to the practice of EBM.
First, the need to develop new skills in searching and critical appraisal can be daunting, although (as we pointed out above) evidence-based care can still be applied if only the former has been mastered and directed toward pre-appraised resources.
Second, busy clinicians have limited time to master and apply these new skills, and the resources required for instant access to evidence are often woefully inadequate in clinical settings.
Finally, evidence that EBM “works” has been late and slow to come.
On the other hand, the ensuing discussion and debate has clarified some “pseudo-limitations” that arise from misunderstandings of the definition of EBM. An examination of the definition and steps of EBM quickly dismisses the criticisms that it denigrates clinical expertise, is limited to clinical research, ignores patients’ values and preferences, or promotes a cookbook approach to medicine. Moreover, it is not an effective cost-cutting tool, since providing evidence-based care directed toward maximizing patients’ quality of life often increases the costs of their care and raises the ire of health economists.
EBM advocates the use of up-to-date "best" scientific evidence from health care research as the basis for making medical decisions.
EBM has three main advantages:
It offers the surest and most objective way to determine and maintain consistently high quality and safety standards in medical practice;
It can help speed up the process of transferring clinical research findings into practice;
It has the potential to reduce health-care costs significantly.
The approach, however, is not without its opponents. These consider that EBM risks downplaying the importance of clinical experience and expert opinion, and that the conditions under which clinical trials used to define best practice take place are hard to replicate in routine practice.
What are the other important uses of EBM?
· It reinforces the need for, and mastery of, the clinical and communication skills that are required to gather and critically appraise patients’ stories, symptoms, and signs and to identify and incorporate their values and expectations into therapeutic alliances.
· It fosters generic skills for use in finding, appraising and implementing evidence from the basic sciences and from other applied sciences.
· It provides an effective, efficient framework for post-graduate education and self-directed, life-long learning; when coupled with “virtual libraries” and distance learning programs it supplies a model of worldwide applicability.
· Although not its primary aim, by identifying the questions for which no satisfactory evidence exists it generates a supremely pragmatic agenda for applied health research (that is formally recognized by groups such as the UK NHS R&D Programme).