Summer 2011
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Evidence-Based Medicine in Clinical Practice
Robert L. Talbert, PharmD, BCPS, FCCP
Professor of Pharmacy, The University of Texas at Austin
Professor of Medicine, University of Texas Health Science Center at San Antonio
San Antonio, TX

Introduction
Though its philosophical origins are said to date back to mid-19th century Paris, evidence-based medicine (EBM) is a medical movement based upon the application of the scientific method to medical practice. EBM recognizes that many long-established medical traditions have not been subjected to adequate scientific scrutiny. According to the Centre for Evidence-Based Medicine, EBM "is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients." (http://www.cebm.net/).

EBM categorizes different types of clinical evidence and ranks them according to the strength of their freedom from the various biases that beset medical research. For example, the strongest evidence for therapeutic interventions comes from randomized, double-blind, placebo-controlled trials (RCT) involving a homogeneous patient population and medical condition, and systematic reviews such as meta-analysis of RCT. In contrast, patient testimonials, case reports, and even expert opinion have little value as proof because of the placebo effect, the biases inherent in observation and reporting of cases, and difficulties in ascertaining who is an expert. Tables 1 and 2 show how evidence from the literature may be classified into various levels. Numerous classification schemes are used, and development and application of the levels of evidence may vary across EBM reports.

Click on tables to enlarge.

Application of EBM in Medicine
Application of EBM in clinical practice may range from nonexistent to practicing and teaching of EBM. Professor Archie Cochrane, perhaps the first proponent of EBM, was a Scottish epidemiologist whose 1972 book Effectiveness and Efficiency: Random Reflections on Health Services and subsequent advocacy led to increasing acceptance of the concepts behind evidence-based practice. His work was honored through the naming of EBM research centers as Cochrane Centres and by establishment of an international organization, the Cochrane Collaboration. Interest in EBM has been growing since Gordon Guyatt first used the term in 1992.1 Today, a Medline search of EBM yields almost 20,000 citations from virtually every area of healthcare, including medicine, nursing and pharmacy.

EBM can be used in the care of individual patients, implementation of treatment algorithms for application across healthcare systems and development of treatment guidelines and protocols. In managed healthcare systems, evidence-based guidelines have been used as a basis for denying insurance coverage for certain treatments-some of which are held by the physicians involved to be effective, but for which RCTs have not yet been published. EBM-based guidelines are now commonly used in evaluating the quality of care provided by individual healthcare providers as well as by healthcare systems for inpatients and outpatients. Based on the data provided to accrediting agencies, a report card is generated, which can be used as a benchmark for national, regional or local standards of care. This provides a mechanism for the institutions providing the report to implement quality improvement programs.

One agency using EBM guidelines to rate quality of care for inpatients is the Joint Commission On Accreditation of Healthcare Organizations (JCAHO). The National Committee for Quality Assurance (NCQA) uses EBM guidelines for outpatients. JCAHO has designated disease states such as acute myocardial infarction for improvement and uses markers such as appropriate drug therapy at the time of discharge (aspirin, beta blockers, statins and angiotensin-converting enzyme inhibitors) as recommended in guidelines published by the American Heart Association and the American College of Cardiology, to determine if high-quality care has been provided. Likewise, NCQA uses guidelines from the National Cholesterol Education Program to determine if lipid management is appropriate.

One commonly used starting source to find clinical treatment guidelines is the National Guideline Clearinghouse (NGC), which is a public resource for evidence-based clinical practice guidelines. NGC is an initiative of the Agency for Healthcare Research and Quality (AHRQ) of the U.S. Department of Health and Human Services. A recent visit to their website indicated that for cardiovascular disease there were 288 guidelines available from all around the world. Indeed, across 23 categories of disease states, this site provides 3,795 guidelines for the treatment of a sundry of disorders.

With all of these guidelines and evidence from the literature, one might conclude that evidence-based recommendations exist for nearly every situation. This is not the case. Individual patients may have co-morbidities that are not addressed in national guidelines or may have disease processes for which no published guidelines exist. Furthermore, new evidence may appear in the literature that necessitates changes in recommendations. An example of how recent RCT findings changed guidelines is the recognition that more aggressive low-density lipoprotein (LDL) cholesterol goals may be appropriate in very high- risk patients.2 Generally speaking, the areas of cardiovascular, infectious and neoplastic diseases have the largest number of published clinical practice guidelines and scientific statements to help guide treatment of individual patients.

Collaboration in the Application of EBM
Any good clinician should be an evidence-based practitioner, and if one has a strong evidence-based database, collaboration naturally follows when interacting with other health care professionals who are also evidence-based practitioners. When interacting in a one-on-one situation, it becomes obvious very quickly if both parties are EBM practitioners, and each will rapidly respect the other's knowledge and logical approach to problem-solving. Collaboration also occurs across healthcare systems, and EBM is frequently used in developing treatment algorithms and protocols as well as guidelines. In many institutions, Pharmacy and Therapeutics (P&T) Committees use an EBM-based approach in formulary management and develop disease-state specific treatment guidelines that are evidence-based for application across the entire institution. Many committees in healthcare systems are interdisciplinary by nature (e.g., Drug Use Evaluation, Infection Control, P&T) and commonly use an EBM approach to enhance the efficacy and safety of drug use in the institution.

Limitations of EBM
Not every conceivable disease or problem has been studied, and for some questions and situations, no evidence-based answer is possible. It is recognized that not all evidence is made accessible, that this can limit the effectiveness of any approach, and that an effort to reduce publication and retrieval biases is required. Failure to publish negative trials is the most obvious gap, and efforts to register all trials at the outset, and then to pursue their results are underway. Changes in publication methods, particularly related to the Internet, should reduce the difficulty of publishing a paper on a trial that concludes it did not prove anything new, including its starting hypothesis. Also, treatment effectiveness reported from clinical studies may be higher than that achieved in later routine clinical practice due to the closer patient monitoring during trials, which leads to much higher compliance rates. Critics of evidence-based medicine maintain that good evidence is often deficient in many areas, that lack of evidence and lack of benefit are not the same, and that the more data that are pooled and aggregated, the more difficult it is to compare the patients in the studies with the patient in front of the doctor, i.e. EBM applies to populations, not necessarily to individuals.

Learning About EBM
Numerous sources of information on EBM exist on web sites, in books, and many review articles on the topic. A good starting place is a chapter written by Chiquette and Posey in Pharmacotherapy: A Pathophysiologic Approach 6th edition. This chapter addresses incorporating EBM into pharmacotherapeutic decision-making sources of information, assessing validity of evidence, determining the relevance of evidence and application of results. Another book that we have found useful in teaching EBM is Evidence-Based Medicine by Sackett, Strauss, Richardson, Rosenberg and Haynes, published in 2000.

The Impact of EBM and Promotion of Its Use
Although there are many examples of the impact of EBM on improvements in patient outcomes, perhaps the CHAMP program (improved treatment of coronary heart disease by implementation of a Cardiac Hospitalization Atherosclerosis Management Program)3 at UCLA is one of the best known. This hospital-based program utilized the "teachable moment" during hospitalization for a coronary event to get patients started on appropriate drug therapy to lower risk of subsequent events. Treatment rates and clinical outcome were compared in patients discharged after myocardial infarction in the 2-year period before (1992 to 1993) and the 2-year period after (1994 to 1995) CHAMP was implemented. In the pre- and post-CHAMP patient groups, aspirin use at discharge improved from 68% to 92% (p <0.01), beta blocker use improved from 12% to 62% (p <0.01), ACE inhibitor use increased from 6% to 58% (p <0.01), and statin use increased from 6% to 86% (p <0.01). Increased use of treatment persisted during subsequent follow-up. There was also a significant increase in patients achieving a LDL cholesterol 100 mg/dl (6% versus 58%, p <0.001) and a reduction in recurrent myocardial infarction and 1-year mortality. Other examples include the recently concluded Asheville Project on improving control in asthma patients4 and improved outcomes in heart failure in a program implemented by pharmacists at Duke.5

Pharmacists may promote the use of EBM to all healthcare professionals by becoming practitioners and teachers of EBM in their daily practices. This entails continuous upgrading of knowledge and skills and a long-term commitment to learning. Promotion can occur on an individual basis and, in my experience, is most effectively promoted by setting an example of maintaining a current personal database and logical application of this evidence from the literature in solving individual problems. Pharmacists should also participate in organizational and institution decision-making processes through participation in committees, task forces and working groups that set policy for drug use in the institution. Pharmacists are openly welcomed by professional organizations such as the American Heart Association, American Society of Clinical Oncology and other groups involved in developing treatment guidelines and developing educational agendas for healthcare professionals.

When challenged on the merits of EBM by other healthcare providers, what should a pharmacist do? The first step is to be as well-prepared as possible by being very familiar with the evidence related to the question at hand. Secondly, search for and locate the relevant published guidelines (frequently more than one exists) and ensure that the nuances of each guideline are well understood. When entering a discussion that may become controversial, have hard copy of the primary studies and guidelines so that no one misquotes what has been published. Lastly, remember that EBM is an approach using the best available evidence. It does not supplant clinical judgment and decision-making, but rather should be used to enhance the decision-making process and achieve the best possible patient outcomes.

References

  1. Guyatt G, Cairns J, Churchill D, et al. Evidence-Based Medicine. A New Approach to Teaching the Practice of Medicine. JAMA 1992;268:2420-5.
  2. Grundy SM, Cleeman JI, Merz CN, et al. National Heart, Lung, and Blood Institute. American College of Cardiology Foundation. American Heart Association. Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines. Circulation. 2004;110(2):227-39.
  3. Fonarow GC, Gawlinski A, Moughrabi S, Tillisch JH. Improved treatment of coronary heart disease by implementation of a Cardiac Hospitalization Atherosclerosis Management Program (CHAMP). Am J Cardiol. 2001;87(7):819-822.
  4. Bunting BA, Cranor CW. The Asheville Project: Long-term clinical, humanistic, and economic outcomes of a community-based medication therapy management program for asthma. JAPhA. 2006;46:133-147.
  5. Gattis WA, Hasselblad V, Whellan DJ, O'Connor CM. Reduction in heart failure events by the addition of a clinical pharmacist to the heart failure management team: Results of the Pharmacist in Heart Failure Assessment Recommendation and Monitoring (PHARM) Study. Arch Intern Med. 1999;159:1939-1945.

Volume 20
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