Definition of Evidence-Based Medicine

Transcription

1 Converting Experience into Evidence-Orienting the Clinician for Scientific Validation Practical Approach Dr. Rangesh Paramesh Senior Medical Advisor, Himalaya Healthcare, Bangalore Evidence in medicine, as in life is essential for guiding decisions. Ayurveda should not be exempt from this rule. Just as the biomedical model of the conventional or allopathic medicine necessitates experimentation and data evaluation in determining effectiveness, so too should Ayurveda modalities undergo the rigors of so called western scientific testing. Physician, as a student of both public health and medicine is interested in what works and what does not in medical practice. Through this paper we discuss Ayurveda as a serious practice having much to offer the biomedical approach to patient care. After evaluating Ayurveda s diffusion and status, then advocate for improved cooperation between alternative and biomedical camps to enhance medical education, research and, of course, practice. Ultimately, we believe that the practice of medicine will benefit from an integrative system, whereby evidence-based Ayurveda and biomedical therapies work in concert to improve the quality of patient care. Evidence is any observable event which tends to prove or disprove a proposition. Scientific method is used as a synonym for evidence. The scientific method or process is fundamental to the scientific investigation and acquisition of new knowledge based upon physical evidence. Science manages new assertions about things with theories, hypotheses and observations. Predictions from these theories are tested by experiment. If a prediction turns out correct, the theory survives, but if a prediction fails the theory fails. Any theory which is strong enough to make verifiable predictions can then be tested scientifically in this way. These are the underlying methods of scientific practice. With them one can determine which theories, hypotheses and observations are true. The scientific method is essentially an extremely cautious means of building a supportable, evidenced understanding of practice of medicine. Experience is the accumulation of knowledge or skill that results from direct participation in events or activities. It is also the content of direct observation. Definition of Evidence-Based Medicine Evidence-based medicine (EBM) is a medical movement based upon the application of the scientific method to medical practice, including long-established existing medical traditions not yet subjected to adequate scientific scrutiny. According to the Centre for Evidence-Based Medicine, "Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence based medicine means integrating individual clinical experience and expertise with the best available external clinical evidence from systematic research." 1

2 More recently it has been described as the "integration of best research evidence with clinical expertise and patient values." Ayurveda and Scientific Practices Ayurveda literature contains adequate recognition and explicit statements on the limitations of the knowledge systems and its domain of applicability. Ayurveda texts give indication that this knowledge system is the product of an active community of physicians that has well established norms to govern itself. There are rules regarding discourses between physicians, admission of students into the fold, ethics of practitioners and manners of settling disagreements and disputes. In fact it is interesting to see that much of the treatise of Charaka Samhita is in the form of a symposium wherein groups of Ayurveda scholars take up a series of topics for discussion. Ayurveda has developed its own theoretical framework to understand the structure and properties of all material things based on the theory of Pancha Mahabhutas (the five primordial elements) which analyses all the constituents of the universe based on the sensory organs that are employed to detect them. They have a theoretical framework based on the three doshas namely Vata, Pitta, and Kapha to understand health and disease. The Ayurvedic Materia Medica lists the properties of literally thousands of plants as well as hundreds of animals and mineral products based on Ayurveda concepts. Thus there is every indication that Ayurveda is indeed a scientific knowledge system by all the above criteria. Experimental method The essence of the modern laboratory method is to isolate any problem from its environment, to eliminate the interlinkages that it has with diverse other factors in nature and to reduce it to the minimum possible number of "controllable" parameters. After this, the parameters are varied (generally one at a time) and its effect on the system is studied. In contrast, the traditional approach attempts to solve problems by taking them in their entirety with all their interlinkages and their complexity. This method of solving problems in their natural setting seems to be efficient in providing balanced solutions. The traditional Indian sciences seem to adopt this holistic method of looking at the world in its integrity. It appears that they seek to systematize commonsense and to make it rigorous rather than destroying its essential unity and its multifacetedness. From ancient times the issue of validating knowledge and experiences had been dealt with very meticulously. This question is nothing new to our tradition. It has been with us all the time. If we turn to the Nyaya Sastra, the rules for what constitutes valid knowledge are quite clearly laid down. It says that there are three sources of valid knowledge: 2

3 1) Pratyaksha or direct observation or experience. Any theory that contradicts direct observation and experience is not considered valid knowledge. 2) Shabda or Agama, which is the accumulated wisdom of our entire tradition found in texts and references. 3) Anumana or inference, which is a source of valid knowledge when it does not contradict direct observation, experience and textual reference. Thus, according to Charaka, science is dependent upon "Yukthi" - a quality of the intellect that enables it to perceive phenomena brought into existence by a multiplicity of causes. Again it means, using Yukthi to bring together appropriate actions and material at the appropriate time and place. Thus the traditional system even in its theoretical formulation, seeks to find ways of living in good health rather than to dissect it or change it in any major manner. Hence it appears that while traditional sciences are indeed built upon a stupendous amount of detailed and minute observations, experiment (in the modern laboratory sense of the word) perhaps does not have a clear counterpart in Ayurveda tradition. The Ayurveda sciences are based upon the above methodology applied in the context of maintaining human health. It is based on rational and scientific principles and is skeptical of any knowledge that is not acquired in pursuance of scientific method and rational means. Ayurveda texts go to the extent of stating that any success achieved without following the correct method is sheer accidental success and it is to be discouraged. Based on this method, Ayurveda has put together an enormous body of observational data under a theoretical framework and developed methodologies and categories which hold good for all three times: past, present and future. It has developed its own concepts on health and ill health, which find support in their theoretical formulations. And these have been validated by practice over thousands of years. Now, when a demand is placed on us that Ayurveda drugs and therapeutics be tested and validated it sounds outlandish. It is doubly so because validation means validating traditional medicine in terms of the currently reigning paradigms which may be based on say the current theories of molecular biology and biochemistry and they prove their practical efficacy by various statistical and other field trials. But the problem is that these theories of molecular biology and biochemistry are totally unstable and constantly changing. How to control this changing phenomenon in medical practice? The only answer is developing a system of evidence based medical practice that stands as a record of experience and expertise for a particular times and applicable as a valid reference for future applications in the changing times. EBM The practice of evidence-based medicine involves the conscientious and judicious use of current best evidence in the health care of individuals and populations. Going through all the processes to make evidence-based decisions can be time consuming, especially if you do not have adequate skills or the time to apply them. Additionally, despite your best 3

4 efforts, you may not be able to find high quality evidence for many of the clinical decisions you must make. However, over the last two decades there have been numerous advances in evidence processing, including the production of streamlined guides to aid in critical appraisal of the literature, evidence-based abstraction services, online and other forms of electronic literature searching, growing numbers of high quality systematic reviews, and frequently updated textbooks in paper and electronic formats. Over time, by learning and practicing critical appraisal and informatics skills, developing a rational and practical approach to uncertainty, and by explicitly incorporating evidence, patient preferences and values into your decision making processes, you will likely become a "connoisseur of evidence". That is, you will develop a taste for continually assessing the evidence upon which you base your clinical decisions, and develop a willingness to seek out and choose high quality pre-appraised and secondary sources of evidence from amongst what is available. Components of EBM 1. Asking the Clinical Question. The clinical question should incorporate four elements (PICO): a.patient Describe the patient as a member of a population in terms of age, sex, ethnic group. Describe the clinical problem in terms of the patient's disease or general health condition. b.intervention The intervention may be any of the following: Clinical examination; Prevention; Prognosis; Etiology; Differential diagnosis; Diagnosis tests; Selfimprovement. c.comparison The intervention that is taken as comparison to the intervention in the statement. d.expected Outcome Ask the following questions: What can I hope to accomplish? Have all clinically relevant options been considered? What could the intervention really affect? 2. Find the Best Evidence. To find the best evidence, one needs to follow these steps: a. Translate the clinical question into a usable search strategy. b. Select an appropriate database resource. c. Enter your search strategy according to the rules of the database you selected. d. Browse the records you located to identify those that you think are best. 3. Critique the Evidence. Papers that are located must be evaluated according to a variety of criteria including: a. Is this evidence valid? Is it true, accurate, correct? b. Is this evidence important? Is it useful in clinical practice? The strategies to determine validity and importance vary according to the intervention you are considering--diagnosis, etiology, treatment, prevention, prognosis, or continuing education. 4. Apply the Evidence. Integrate the evidence into your clinical practice. 5. Evaluate the Performance. Since EBM is process-oriented, you will need to consider and evaluate your performance as you progress from Step One through Step Five. This section will suggest specific evaluation criteria to consider for each step. 4

5 Some Tips The practice of evidence based medicine can be divided into the following components: Identifying a problem or area of uncertainty Asking a relevant, focused, clinically important question that is answerable Selecting the most likely resources to search Searching, and appraising the evidence found Assessing the clinical importance of the evidence Assessing the clinical applicability of the evidence Acting on and appropriately applying the evidence Assessing the outcomes of your actions Authoring-summarizing and storing records for future reference Asking Answerable Questions The inability to ask a focused and precise clinical question can be a major impediment to evidence-based practice. Clarify clinical questions and consider best potential sources of evidence doing by the following: 1. Ask: "Is this a question about foreground or background knowledge?" a. Background knowledge questions are general questions about conditions, illnesses, syndromes and patterns of disease, and pathophysiology. They are usually composed of a question root (what, where, why, when, how) + a verb + a condition. For example, "What is the typical clinical presentation of Addison's disease?" A novice more commonly asks this type of question in a particular knowledge area, in order to gain a general understanding of clinical issues. Best resources include evidence based textbooks and reviews. b. Foreground questions are more often about issues of care. They query specialized and distinct knowledge needed for specific and relevant clinical decision-making. Components of a well-built foreground question include "PICO". Best resources may include an evidence-based abstraction service, guidelines, systematic reviews, or some evidence-linked textbooks, but may also include the primary literature. The need for skills in searching and critical appraisal is greatest when searching for evidence in the primary literature. 5

6 2. Pay attention to the question's component parts, especially for foreground questions. A useful mnemonic is "PICO" a. P patients or populations b. I interventions c. C comparison group(s) or "gold standard" d. O outcome(s) of interest 3. Classify the question into a domain: a. Therapy b. Diagnosis c. Prognosis d. Harm or Causality 4. Ask: "How likely is it that there are high quality summaries or studies with valid and clinically important evidence specifically addressing this issue?" Searching Effectively Sources of information and evidence may include: Colleagues Textbooks Journal articles Guidelines Where to start searching depends on a number of factors: Available time Available databases PICO and domain of the question asked Foreground versus background knowledge required How well the issue lends itself to study Critical Appraisal and Properties of Information Attribute Quality Format Validity Can I trust this information? Is there a high density of valid information? Clinical Importance If true, will the use of this information make an important difference? Is this importance highlighted in the resource? Applicability Can I use the information in this instance? Does the resource have guides to application? 6

7 Is my practice evidence based? A context specific checklist for individual clinical encounters. Have you - 1 Identified and prioritized the clinical, psychological, social, and other problems, taking into account the patient's perspective? 2 Performed a sufficiently competent and complete examination to establish the likelihood of competing diagnoses? 3 Considered additional problems and risk factors? 4 Where necessary, sought relevant evidence--from systematic reviews, guidelines, clinical trials, and other sources? 5 Assessed and taken into account the completeness, quality, and strength of the evidence, and its relevance to this patient? 6 Presented the pros and cons of the different options to the patient in a way they can understand, and incorporated the patient's utilities into the final recommendations? Conclusion Evidence based medicine is not "cookbook" medicine. Because it requires a bottom up approach that integrates the best external evidence with individual clinical expertise and patients' choice, it cannot result in slavish, cookbook approaches to individual patient care. External clinical evidence can inform, but can never replace, individual clinical expertise and experience, and it is this expertise that decides whether the external evidence applies to the individual patient at all and, if so, how it should be integrated into a clinical decision. Similarly, any external guideline must be integrated with individual clinical expertise and experience in deciding whether and how it matches the patient's clinical state, predicament, and preferences, and thus whether it should be applied. Clinicians who fear top down cookbooks will find the advocates of evidence based medicine joining them at the barricades. Doctors practicing evidence based medicine will identify and apply the most efficacious interventions to maximize the quality and quantity of life for individual patients; this may raise rather than lower the cost of their care. Evidence based medicine is not restricted to randomized trials and meta-analyses. It involves tracking down the best external evidence with which to answer our clinical questions. To find out about the accuracy of a diagnostic test, we need to find proper cross sectional studies of patients clinically suspected of harboring the relevant disorder, not a randomized trial. For a question about prognosis, we need proper follow up studies of patients assembled at a uniform, early point in the clinical course of their disease. And sometimes the evidence we need will come from the basic sciences such as genetics or immunology. It is when asking questions about therapy that we should try to avoid the non-experimental approaches, since these routinely lead to false positive conclusions 7

8 about efficacy. Because the randomized trial, and especially the systematic review of several randomized trials, is so much more likely to inform us and so much less likely to mislead us, it has become the "gold standard" for judging whether a treatment does more good than harm. However, some questions about therapy do not require randomized trials (successful interventions for otherwise fatal conditions) or cannot wait for the trials to be conducted. And if no randomized trial has been carried out for our patient's predicament, we must follow the trail to the next best external evidence and work from there. Despite its ancient origins, evidence based medicine remains a relatively young discipline whose positive impacts are just beginning to be validated, and it will continue to evolve. This evolution will be enhanced as several undergraduate, postgraduate, and continuing medical education programmes adopt and adapt it to their learners' needs. These programmes, and their evaluation, will provide further information and understanding about what evidence based medicine is and is not. References: David Sackett, et al. "Evidence Based Medicine: What It Is and What It Isn't," BMJ 312, no.7023, 71-72, (1996). David Sackett, et al. Evidence-Based Medicine: How to Practice and Teach EBM (New York: Churchill Livingstone, 2000), 1. Greenhalgh, T. Is my practice evidence-based? BMJ 313, no.7063, , (1996). Anonymous. Indian Health Traditions, Hindu Folio, October08,