Evidence-Based Medicine

OVERVIEW

Sackett et al (1996) originally defined Evidence-Based Medicine (EBM) as “the conscientious and judicious used of current best evidence from clinical research in the management of individual patients”.

EBM:

• is the process of systematically reviewing, appraising and using clinical research findings to aid the delivery of optimal clinical care to patients
• involves considering research and other forms of evidence on a routine basis when making healthcare decisions — such decisions include the clinical decisions about choice of treatment, test, or risk management for individual patients, as well as policy decisions for groups and population
• is “a continuously evolving heuristic structure for optimizing clinical practice” (Djulbegovic et al, 2009)

There are >2,000,000 papers published each year, but our patients only benefit from a tiny fraction of these papers (Glasziou, 2008)

“… staff of the journal Evidence-Based Medicine… hand-search about 60,000 articles from 140 journals annually, including the five highest-rating general medical journals and a variety of other specialty journals… the “number needed to read” to find one valid study is about 18 articles.” – Glasziou (2008)

STEPS OF EVIDENCE-BASED PRACTICE

Five steps of evidence-based practice

1. Translation of uncertainty to an answerable question (ask question)
2. Systematic retrieval of best evidence available (find evidence)
3. Critical appraisal of evidence for validity, clinical relevance, and applicability (critically appraise)
4. Application of results in practice (make clinical decisions)
5. Evaluation of performance (audit)

FOCUSED CLINICAL QUESTIONS

A good question follows the PICO format and includes:

1. the Patient or problem being addressed
2. the Intervention or exposure being considered
3. the Comparison intervention or exposure, when relevant
4. the clinical Outcomes of interest

ADVANTAGES OF EBM

• our reading habits and critical appraisal skills improve
• it leads us to ask questions and be more sceptical of the answers
• wasteful practices can be abandoned
• presupposes that we keep up-to-date
• makes the decision-making process transparent to colleagues and patients, and involves them
• leads to greater appreciation of the evidence for our practice, and the inherent uncertainties

CRITICISMS OF EBM

Application

• time-consuming and expensive (for the bedside clinician and the researcher creating high-quality evidence)
• sometimes impossible (when there is no published literature on a question)
• large amount of low-quality research to filter (information overload)
• useful research articles may be disregarded because of minor blemishes (‘rescue bias’)
• uncertainty about how robust evidence needs to be for use to incorporate into clinical practice
• external validity is subjective and evidence can be misapplied
• it is never ‘up-to-date’ and subject to change (… that’s life!)
• detached from “basic science” (however, Ioannidis (2017) has argued that EBM is THE basic science of medicine)
• downplays the importance of clinical expertise and tacit knowledge derived from clinical apprenticeship
• not proven to be superior to other models of clinical practice
• perceived as a “cult”
• vested interests misappropriate the EBM label as a “quality mark” (Greenhalgh et al, 2014)

Evidence

• “easy-to-prove” interventions and “positive results” are more favoured in literature
• tends to emphasise the priority of randomised controlled trials (RCTs) (which have inherent limitations) to the exclusion of other study designs (which may be appropriate in certain settings)
• many large trials have conflicts of interest and are done by and for the benefit of the industry
• meta-analyses and guidelines are often based on low-quality evidence and may also be subject to conflicts of interest
• trials with excellent internal validity may not ask research questions that matter to patients, or have outcomes that do not matter to patients (e.g. surrogate outcomes)
• trials tend to focus on demonstrating benefits rather than adverse events
• promotes perverse incentives for researchers (“publish or perish”); e.g. authors names on papers to which they have made little contribution, funding of principal investigators who are primarily managers effective at attracting funding
• trials often exclude patient groups that pose the most challenging clinical problems
• focuses on “population averages” that may be difficult to apply to individual patients

RESPONSE TO CRITICISMS

Many of the criticisms of EBM result from misrepresentation (e.g. trials trump patient values) or misapplication (e.g. only RCTs matter), and most of the deficiencies are not inherent to EBM (e.g. conflicts of interest) (Ioannidis, 2017)

“EBM still remains an unmet goal, worthy to be attained.” – John Ioannidis, 2016″

Individual clinical expertise includes clinical judgment, patient preferences, and patienteclinician communication, all these skills are at the core of practicing EBM.”- John Ioannidis, 2017

Greenhalgh et al (2014) state that “real” EBM:

• Makes the ethical care of the patient its top priority
• Demands individualised evidence in a format that clinicians and patients can understand
• Is characterised by expert judgment rather than mechanical rule following
• Shares decisions with patients through meaningful conversations
• Builds on a strong clinician-patient relationship and the human aspects of care
• Applies these principles at community level for evidence based public health

References and Links

Journal articles

• Charlton BG. The Zombie science of evidence-based medicine: a personal retrospective. A commentary on Djulbegovic, B., Guyatt, G. H. & Ashcroft, R. E. (2009). Cancer Control, 16, 158-168. J Eval Clin Pract. 2009;15(6):930-4. [PMID 20367686]
  
• Dawes M, Summerskill W, Glasziou P, Cartabellotta A, Martin J, Hopayian K, Porzsolt F, Burls A, Osborne J; Second International Conference of Evidence-Based Health Care Teachers and Developers. Sicily statement on evidence-based practice. BMC Med Educ. 2005 Jan 5;5(1):1 [PMC544887]
• Djulbegovic B, Guyatt GH, Ashcroft RE. Epistemologic inquiries in evidence-based medicine. Cancer Control. 2009;16(2):158-68. [PMID 19337202]
  
• Evidence Based Medicine Working Group. Evidence based medicine. A new approach to teaching the practice of medicine. JAMA 1992;268:2420-5. [PMID 1404801]
  
• Glasziou PP. Information overload: what’s behind it, what’s beyond it? MJA 2008; 189(2): 84-85 [PMID 18637773]
  
• Greenhalgh T, Howick J, Maskrey N, Evidence Based Medicine Renaissance Group. Evidence based medicine: a movement in crisis? BMJ 2014;348:g3725. [PMC4056639]
• Greenhalgh T. Why do we always end up here? Evidence-based medicine’s conceptual cul-de-sacs and some off-road alternative routes. J Prim Health Care 2012;4:92e7. [PMID 22675691]
  
• Ioannidis JP. Evidence-based medicine has been hijacked: a report to David Sackett. J Clin Epidemiol. 2016;73:82-6. [PMID 26934549]
  
• Ioannidis JPA. Hijacked evidence-based medicine: stay the course and throw the pirates overboard. J Clin Epidemiol. 2017;84:11-13.  [PMID 28532611]
  
• Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS. Evidence based medicine: what it is and what it isn’t. BMJ. 1996 Jan 13;312(7023):71-2 [PMC2349778]
• Shaw D, Elger B. Evidence-based persuasion: an ethical imperative. JAMA. 2013 Apr 24;309(16):1689-90. doi: 10.1001/jama.2013.2179. [PMID 23568671]
  

FOAM and web resources

• CEM — What is EBM?