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Keywords:

  • evidence-base;
  • medicine;
  • optometry;
  • practice

In a scenario set to be played out across the country with increasing frequency over the coming years, an optometrist discusses the management options available to an elderly patient diagnosed with high-risk, early age-related macular degeneration (AMD). The patient is 73 years old, a smoker and a first-generation Australian of Mediterranean descent. Clinical examination of the patient has revealed the presence of multiple large drusen and pigmentary abnormalities all within 1,500 microns of the foveae. Visual acuity is R 6/7.5 and L 6/9.5. The patient asks what her risks are of losing her sight, and whether she should take one of the dietary supplements marketed for preserving macular health.

To answer the patient's questions appropriately demands that the optometrist understand the natural history of age-related macular degeneration, specifically the risk of progression to advanced AMD, the evidence for the safety and efficacy of various approved and experimental treatments for the condition and importantly, the relevance of that evidence, as it is applied to this patient. In short, an evidence-based approach to the practice of optometry. Yet, there is sufficient anecdotal evidence to suggest reluctance among some optometrists to embrace evidence-based practice (EBP) and the question should be asked, why? The answer may well be found in a lack of understanding of EBP and what constitutes evidence, which I address in this article.

Background

  1. Top of page
  2. Background
  3. Evidence-based practice is not without controversy
  4. What is evidence-based practice?
  5. Evidence
  6. Clinical Expertise
  7. Cause of Confusion
  8. Recommendations
  9. References

Although the philosophical origins of evidence-based medicine (EBM) can be traced back to the mid-1900s and the French physiologist Claude Bernard,[1] the programmatic outline for EBM is more contemporary, being contained in a series of lectures given in 1972 by epidemiologist Archie Cochrane. Cochrane argued that interventions of dubious or unknown safety and efficacy were causing harm, including the waste of resources, at both individual and population levels, that treatments should be evaluated systematically, using unbiased methods of evaluation and that individual practitioners and the medical profession as a whole should continuously review and appraise their own state of knowledge.[2] It was not until some two decades later after the publication in 1992 of Evidence-Based Medicine – A New Approach to Teaching the Practice of Medicine by the Evidence-Based Medicine Working Group chaired by Gordon Guyatt[3] that EBM gained widespread attention. Now, a decade into the 21st century, EBM or more generally, EBP, is almost unavoidable in the common discourse and in the scientific and professional literature but, perhaps, less so in optometry than other healthcare professions. As observed by Adams in 2007,[4] optometry is moving to a more formalised clinical application of research results in the adoption of an evidence-based approach to education and practice. If only as measured against the initiatives described by Anderton,[5] also in 2007, little progress seems to have been made in the interim and it can be argued that one possible reason for the slow pace has been confusion as to what constitutes evidence in EBP.

Evidence-based practice is not without controversy

  1. Top of page
  2. Background
  3. Evidence-based practice is not without controversy
  4. What is evidence-based practice?
  5. Evidence
  6. Clinical Expertise
  7. Cause of Confusion
  8. Recommendations
  9. References

Despite its growing acceptance and importance EBM has not been without controversy. Indeed its origins lie in the then controversial challenge by Bernard of the pretence that medicine was an art strictly based on intuition and tact.[1] Various criticisms of EBM and EBP by extension, as dated, a dangerous innovation, cookbook medicine, suppressing clinical freedom, and serving the interests of cost-saving administrators, are well-countered elsewhere.[3, 6] The epistemological arguments about propositional knowledge and evidence[2] are more complex and perhaps better left to philosophers than clinicians. Despite these criticisms and minor controversies, the adoption of an evidence-based approach to optometric education and practice seems not just unavoidable but desirable and therefore, it is important to investigate optometric understanding of EBP.

What is evidence-based practice?

  1. Top of page
  2. Background
  3. Evidence-based practice is not without controversy
  4. What is evidence-based practice?
  5. Evidence
  6. Clinical Expertise
  7. Cause of Confusion
  8. Recommendations
  9. References

In describing EBM as a paradigm shift for medical practice, driven in part by the emergence of clinical trial methodology, three assumptions of the approach have been set out, including:[3]

  1. the importance of clinical expertise
  2. the inadequacy, in isolation, of basic pathophysiologic principles and
  3. the necessity of understanding certain rules of evidence when interpreting the literature in solving clinical problems.

Sackett and colleagues[6] took this further in defining EBM as ‘the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients.’ In also stating ‘(t)he practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research’, Sackett and colleagues[6] made clear their use of the term ‘evidence’ in this context to mean external research evidence.

The contextual dimensions to EBM were made slightly more explicit in a subsequent, simplified definition of EBM as ‘the incorporation of the highest quality of information, derived from scientific study, into the context of clinical care’ and explained as ‘practically, evidence-based medicine involves defining an evidence-based problem identifying and critically appraising the best available scientific evidence to answer the problem and deciding on the most appropriate course of action for a given patient.’[7] Although Sackett and colleagues[6] did comment on the consideration of an individual patient's predicament, rights and preferences as reflections of increased clinical expertise, more recent models of EBP have placed greater emphasis on patient (or client) values and circumstances and the practice context, by separating those out from clinical expertise.[8]

The purpose of EBP is to assist in clinical decision making. Although more recent statements[9] on EBP describe clinical decision making ‘to include clinical reasoning, problem solving and awareness of patient and health care context’, there remains disagreement as to who makes those decisions; however, that is an argument beyond the scope of this paper.

Evidence

  1. Top of page
  2. Background
  3. Evidence-based practice is not without controversy
  4. What is evidence-based practice?
  5. Evidence
  6. Clinical Expertise
  7. Cause of Confusion
  8. Recommendations
  9. References

Since Cochrane's lectures, there has been great discussion on the hierarchy of evidence, a qualitative ranking of different types of evidence and the related discussions of how to combine and how to compare different sorts of evidence.[2] With only minor exceptions, the evidence in EBM has been discussed in terms of external or scientific research evidence. One need look no further than the paper NHMRC levels of evidence and grades for recommendation for developers of guidelines published in 2009 by the National Health and Medical Research Council of Australia and the accompanying handbooks, in particular How to Review the Evidence: Systematic Identification and Review of the Scientific Literature and How to Use the Evidence: Assessment and Application of Scientific Evidence, to find local and contemporary confirmation of this interpretation.[10]

The concepts of evidence and information are closely connected but information is often perceived as a wider term, or as having broader appeal. As discussed by Yeo,[11] unlike evidence, ‘information does not necessarily make explicit reference to the process of discriminating among hypotheses we entertain.’ In the context of EBP it is advisable to use the terminology precisely and thereby avoid potential confusion.

Clinical Expertise

  1. Top of page
  2. Background
  3. Evidence-based practice is not without controversy
  4. What is evidence-based practice?
  5. Evidence
  6. Clinical Expertise
  7. Cause of Confusion
  8. Recommendations
  9. References

The importance of the clinical examination is not challenged by EBM despite occasional claims to the contrary.[3] Indeed, clinical expertise and the clinical examination are considered to be central to the practice of EBM, as evident in the statements by Sackett and colleagues,[6] namely, ‘(c)linical expertise is the proficiency and judgement that individual clinicians acquire through clinical experience and clinical practice’ and ‘(e)xternal clinical evidence can inform but never, replace, individual clinical expertise’ and ‘careful history taking and physical examination provide much, and often the best, evidence for diagnosis and treatment decisions.’[3]

It is reasonable to suggest that undergraduate and postgraduate training, combined with clinical experience and practice, are important contributors to the development of clinical expertise. Various other sources of information, which contribute to clinical expertise can be suggested, although their relative importance remains unclear.

Cause of Confusion

  1. Top of page
  2. Background
  3. Evidence-based practice is not without controversy
  4. What is evidence-based practice?
  5. Evidence
  6. Clinical Expertise
  7. Cause of Confusion
  8. Recommendations
  9. References

The recent article by Suttle, Jalbert and Alnahedh[12] provided valuable insight into optometric understanding of the concepts of clinical evidence, the sources of information underpinning clinical expertise and the principles of EBP. In reporting the various sources of information considered by optometrists to underpin their clinical decisions, it should be no surprise that a patient's history, signs and symptoms were ranked as the first or second most important factor. They are the basics of a clinical examination. The sources of information which are important to clinical decision making should be read in the context of the development of clinical expertise, as described by both Guyatt and Sackett and not as (external research) evidence in the practice of EBM. Accordingly, one can argue that the other factors listed by Suttle, Jalbert and Alnahedh[12] are appropriately described as sources of information important to the development of clinical expertise but not as evidence, because the EBM literature is consistent in its use of evidence to mean external research evidence. To do otherwise, as they have done throughout their report, is potentially confusing.

Although Guyatt did describe careful history taking and physical examination as sources of evidence for decisions on diagnosis and treatment[3] and in this instance, the physical examination can be rightly called evidence, being observable phenomena,[11] it is arguably better to refer to history taking and the physical examination as sources of information (using the more general term), rather than evidence because of the specific meaning and otherwise consistent use of the term evidence in EBP.

In addition, despite Suttle, Jalbert and Alnahedh[12] acknowledging that they did not provide a definition for EBP as part of their survey, to leave the meaning open to interpretation has clearly added to the confusion of those surveyed. As suggested by Beaumont, Madigan and Mathew,[13] ‘(i)t is important to ensure that the questions are not liable to bias because of the inability of the respondent to report accurately … and to assess if the responses suggest biases because of misleading or misunderstood questions …’

It is important for optometry to understand and embrace EBP. The identification of the sources of information used by optometrists to underpin their clinical decisions is an important step in that process. Those should not be confused with the sources of external research evidence, which are at the very core of EBP.

Recommendations

  1. Top of page
  2. Background
  3. Evidence-based practice is not without controversy
  4. What is evidence-based practice?
  5. Evidence
  6. Clinical Expertise
  7. Cause of Confusion
  8. Recommendations
  9. References

The credibility of optometry as a therapeutically endorsed, primary eye-care profession demands the adoption of an evidence-based approach to both optometric education and practice. The recent announcement of funding to undertake a review and renewal of the current optometric curricula to ensure that graduates have the skills, knowledge and attitude needed for EBP is an important step forward in that process; however, that does little to assist those already in practice.

I propose two simple measures to facilitate optometric understanding of EBP:

  1. precise use of terminology, in particular the term evidence, to avoid confusion and
  2. provision of continuing professional development activities to support practising optometrists as they develop an understanding of, and a personal approach for, interpreting and integrating the best clinical research evidence in caring for their patients.

Returning to the example stated at the beginning of this article, governments, other healthcare practitioners and our patients, expect practising optometrists to be able to critically appraise the available and emerging evidence, as it relates to the use of dietary supplements in the slowing or prevention of progression to advanced age-related macular degeneration. More generally, it is time for the profession to put in place the resources to facilitate an understanding and the adoption of an evidence-based approach to optometric practice.

References

  1. Top of page
  2. Background
  3. Evidence-based practice is not without controversy
  4. What is evidence-based practice?
  5. Evidence
  6. Clinical Expertise
  7. Cause of Confusion
  8. Recommendations
  9. References