The Practice of Evidence-Based Medicine

The identification of a clinical goal provides the foundation of the service provided by the healthcare professional. In the area of laboratory medicine, as described later in this chapter, the goal can be expressed in terms of answering a clinical question appropriate laboratory investigations help to answer the question. Knowledge of the characteristics of these investigations is needed to decide which test to use, when to use it, and how to interpret the results. 

Finding and appraising knowledge that is relevant to the question requires awareness of the information resources 

A knowledge resource in the form of systematic reviews (see later in this chapter) should provide the critically reviewed evidence of the efficacy, benefits, limitations, and risks from using a test, intervention, or device. Access has classically been through scientific journals and textbooks, and electronic communication of various sorts (includmg textbooks and journals) is making access faster and more up to date. 

Knowledge on the use of a test or intervention ultimately has to be placed in the context of a clinical and economic accountability framework and ensuring the highest quality and lowest risk to patients. Clinical audit is a key element of meeting this objective. 

When a patient has symptoms or signs of a health problem, the clinician establishes hypotheses about their etiology. Competing hypotheses must be resolved. After decisions are made about the nature of the condition, the process of care may then involve further decisions depending on the nature of the problem or disease. The services of laboratory medicine are one of the tools at the disposal of the clmician to answer the questions posed by the hypothesis generation and to help make decisions.  

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Throughout this book there has been an emphasis on the acquisition of optimum quality data. As well as presenting this optimum quality data to regulatory agencies, it is imperative to present optimum quality data to readers of the clinical literature. It is of the utmost ethical importance that clinical communications are prepared to the highest degree of science and ethics, since clinicians may base the treatment of individual patients on evidence published in clinical communications in their practice of evidence-based medicine (see Section 13.7). 

From a clinical practice perspective, a clinician s treatment of a patient may be influenced by the results of a meta-analysis. Therefore, if the result is influenced by the fact that the articles included in the analysis were not truly representative of all evaluations of the treatment, the result is not likely to be representative either. The issue of publication bias therefore is of critical importance in the context of evidence-based medicine. 

The components of the audit cycle are depicted in Figure 13-8. All of the audit activities are found in the practice of evidence-based laboratory medicine, namely that there is a... 

Guyatt G, Haynes B, Jaeschke R et al. Introduction the philosophy of evidence-based medicine. In Guyatt G and Rennie D (editors) User s Guide to the Medical Literature. A manual for evidence-based chnical practice. JAMA and Archive Journals, American Medical Association, Chicago, 2002 3-12. 

For more background, teaching and help on the practice of EBM the database at the Centre for Evidence Based Medicine (CEBM 2008) can be of help. 

The second component of evidence-based medicine is clinical practice (see also Mayer, 2004 Straus et al., 2005). Clinicians have the responsibility of providing the best possible care to each of their individual patients. One part of being able to provide this optimum care is remaining aware of pertinent evidence that is published in clinical communications (as mentioned in the previous section, this is no small task). It is also incumbent on clinicians to be able to decide for themselves if the evidence presented in a clinical communication is good evidence and if the message of a systematic review or a meta-analysis is justified based on the quality of the report. As Katz (2001) commented ... 

The FDA is part of the system of medical practice prevalent in the United States of evidence-based medicine. This means that there is objective evidence that a given therapy works. Within the execution of a more liberal practice of medicine, if a trial has shown that a particular beta-blocker works against a placebo, then physicians have the right to substitute a drug in the same class. 

Johnson BCP (2005) Practicing responsible evidence-based medicine Applications for the management of MS patients. Inti J MS Care 6(4) 4-8. 

APPLYING THE PRINCIPLES OF EVIDENCE-BASED LABORATORY MEDICINE IN ROUTINE PRACTICE... 

It is hopefully clear from the foregoing discussion that the principles of evidence-based laboratory medicine can underpin the way in which laboratory medicine is practiced, from the discovery of a new diagnostic test through to its application in routine patient care. The principles provide the logic on which aU of the elements of practice are founded. The tools of evidence-based laboratory medicine provide the means of delivering the highest quality of service in meeting the needs of patients and the healthcare professionals who serve them. The application of evidence-based practice is far more complex in the case of laboratory medicine than in the major area in which such principles have previously been applied, namely the pharmaceutical intervention. 

Drummond MF, Richardson WS, O Brien BJ, et al. Users guides to the medical literature XIII. How to use an article on economic analysis of clinical practice. A. Are the results of the study valid Evidence-Based Medicine Working Group. JAMA 1997 277 1552-1557. 

The safety interventions are grounded in clinical practice and evidence based medicine. The goals are to deliver evidence based practice reliably and without harming patients. That is, of course, every clinician s goal however, as we have seen, the tricky part is making that happen. The approach has five key components (Pronovost, Berenholtz and Needham, 2008) ... 

The second component of evidence-based medicine is clinical practice. Clinicians have the responsibility of providing the best possible care to each of their individual... 

This bias—a tendency to place high value on a small sample that is flawed due to inadequate sampling technique—underlies much of the argument about evidence-based medicine and best practice guidelines. Those who strongly support the evidence-based/best practice approach see those who resist it as tending to rely too heavily on their individual clinical experience. Another place where sample bias frequently shows up is in the exclusive use of outcome measures as a proxy with which to monitor month-to-month or quarter-to-quarter exposure. Outcome data usually provide an inadequate sample of exposure, because severe adverse events... 

The point is that the practice of medicine should be based on empirical evidence, not on its absence. I do not have to prove that antidepressants do not work. Instead, it is the job of the drug companies to prove that they do work. If the trials were flawed, then clinically significant differences between antidepressant and placebo have not been established for most patients. If the trials were not flawed, the data indicate that clinically significant differences between antidepressant and placebo have not been established for most patients (quoted from the previous sentence). Either way, the objective of proving the effectiveness of antidepressant medication has not been met. 

Since its inception the NNT has been widely used not only to report the results of individual clinical trials, but more particularly in the evidence-based medicine world to report the results of systematic reviews, or meta-analyses (see Section 8.6). Its use by the evidence-based medicine fraternity has led to the NNT being incorporated into a number of treatment guidelines. Three of four recent clinical practice guidelines issued by the Australian and New Zealand College of Psychiatrists used the NNT in summarising results. Despite its popularity with clinicians, not all statisticians have been as supportive. ... 

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