Contents
| A users guide Alejandro R Jadad 7 From trials to decisions: the basis of evidence based health care
Health care decisions are usually the result of the interaction of the information available to the decision makers, their values and preferences, and the circumstances or context in which the decisions are made.1 Randomised controlled trials (RCTs), even if assembled into a perfect systematic review, are just one of the many different types of information that can inform decisions. In this chapter, I describe the different types of information that can influence the role of RCTs in decision making, and how such information can be processed, modulated, and integrated into decisions, according to different values, preferences, and circumstances. What types of information can be used to make health care decisions?Decisions can be influenced by formal research studies or by anecdotal information. By anecdotal information I mean any type of information informally gained, from either personal or clinical experiences, one's own or that of others, without the use of formal research methodology.2 If you want to understand the role of RCTs in decision making, it is crucial that you recognise that RCTs are just one of many different types of research studies, and that research studies are just one type of information. You should also realise that the interaction between different types of information in health care decision making is perhaps as complex and poorly understood as the interaction of information, values, preferences, and circumstances. The obvious first step to exploring this interaction is a basic understanding of the different types of information that you can use to make decisions. Let's start with formal research. What are the different types of research studies? What is a quantitative study? When the investigators do not influence the course of the events, the studies are called observational. These studies can be controlled or non-controlled and, depending on how the data are gathered in time, they can be prospective, retrospective, or cross sectional. The controlled observational studies can be classified further into those with contemporaneous controls (studies in which data from the different groups are obtained during the same period of time) and those with historical controls (data from one or more groups gathered at different points in time). It has been shown that, other things being equal, observational controlled studies with historical controls tend to favour the new intervention more frequently than those with contemporaneous controls.3 Specific examples of observational studies include cohort studies (usually prospective with contemporaneous or historical controls), case-control studies (retrospective and usually with contemporaneous controls), and surveys (cross sectional and usually non-controlled). A detailed description of the different types of observational studies can be found elsewhere.4,5 We still know much more about RCTs than we do about other study designs. Therefore, we also need to improve our understanding of these designs, and learn more about how to weight the evidence provided by studies with various designs and different degrees of methodological rigour. We tend to place RCTs at the top of the evidence hierarchy, assuming that RCTs are always better than other study designs. This is reflected in most of the levels of evidence produced as part of guideline development processes or to teach evidence based decision making.6,7 These levels of evidence, which may have didactic value, may not be appropriate in practice, where we are confronted with studies of different types and with different levels of methodological rigour. For instance, it might be incorrect to give more weight to a flawed RCT than to a rigorous cohort study. What is a qualitative study?A qualitative study is a study that does not attempt to provide quantitative answers to research questions. Instead, the objective is to try to interpret events or things in their natural settings and to develop conceptual frameworks about social phenomena.8 In qualitative studies, the following happens:
Are there different types of qualitative studies? Are quantitative and qualitative research approaches mutually exclusive? At this point, it is important for you to remember that information can be obtained not only from research studies but also outside of formal research activities. This information can have a profound influence on health care decisions. Anecdotes, for instance, can be used to convey ideas and influence behaviour, and make causal inferences. The first two (convey ideas and influence behaviour) are well established, but the last (causal inferences) is very controversial. A large body of experimental research has shown that anecdotes are very convenient and efficient vehicles for conveying information and modifying behaviour.11,12 A number of independent but related factors contribute to the impact of anecdotal information. One of the most important factors is that anecdotal information has emotional interest. Events that happen to us personally are more interesting than those that happen to others; those that happen to people we know, respect, or care about are more persuasive than those that occur to strangers or people about whom we have neutral feelings.2 Another important factor is the vividness of the anecdotal information. Face to face recommendations have been shown experimentally to be more influential than informationally superior data presented impersonally.13,14 Health care recommendations by a respected local peer were shown to be a more powerful force for change in clinical practice than were evidence based consensus guidelines published nationally.15 The role of informal observation as a source of information to guide health care decisions is much more controversial. As human beings, we tend to make inferences from anecdotal information using simple rules of thumb, also known as heuristics, which allow us to define and interpret the data of physical and social life, and to reduce complex tasks to much simpler operations. These rules of thumb are essential for everyday life, and will often lead to correct and useful conclusions. Data can, however, be misperceived and misinterpreted. To the extent that motivation influences behaviour, inferences can be distorted by needs and wishes, and the rules of thumb can lead to incorrect and potentially harmful conclusions. Remarkably little attention has been paid to the value of anecdotal information in health care decision making at all levels. We need more research on the role of anecdotes in health care decisions, because most of the research on this type of information and its role in human inference and decision making has been conducted by social and cognitive psychologists. In the meantime, we should acknowledge the role of anecdotal information in health care decisions. Ignoring its powerful influence is likely to hinder communication among decision makers, and to retard their uptake of research evidence. Anecdotal information should be considered a complement to, rather than a replacement for, formal research evidence. They could also be used as vehicles to deliver the results of formal research to people involved in decisions, regardless of their background. How can information be integrated into decisions?At this point, I hope that you are convinced that information is an essential component of decisions. At the same time, I hope that you do not think that information is sufficient to make decisions. It does not matter how much information you have or how valid and relevant it is, it should always be modulated by the values and preferences of the decision makers and those who will be affected by the decisions, and the circumstances in which the decisions are made. You will even see that, in some cases, your values (both as consumer or provider of health care), your knowledge of other individuals involved in a particular decision, the particular characteristics of the setting in which the decision is being made, and your own previous experiences will be more important than the more generalised evidence from even the best formal research studies. In other cases, the research evidence will be so compelling that it will be very difficult for you to ignore it or to justify decisions that depart from it. In most cases, however, it will be unclear how much your anecdotal information, values, and preferences (and those of others involved in the same decision) should modulate the research evidence available. As a clinician, you will find yourself constantly walking a fine line parallel to that walked by patients and other lay members of the public involved in health care decisions, including your own. The need to walk this fine line in safe and responsible ways is what motivates the supporters of evidence based health care. What is evidence based health care?Evidence based health care (EBHC) is a term used to describe the explicit, conscientious, and judicious use of the currently best available evidence from research to guide health care decisions.16 There are other related terms, most of which are used interchangeably. The first term used, evidence based medicine,17 focused primarily on physicians and medicine. Other terms proposed since include evidence based decision making, which refers to the process itself, independently of the particular area or even outside health care; and evidence based practice, used by the US Agency for Health Care Policy and Research to designate a series of centres in North America, which have been charged with producing evidence reports and technology assessments to support guideline development by other groups.18. More recently, more specific terms have been emerging. These include evidence based management,19 evidence based nursing,20 evidence based mental health,21 evidence based chaplaincy,22 and so on.23 What are the elements of EBHC?From the above definition, any activity related to EBHC should be:
Even though many decision makers (particularly clinicians with a long trajectory) could claim that EBHC has been practised for many decades, others purport that EBHC is a new process of decision making which includes a new blend of elements, and even constitutes a paradigm shift in health care.17,24 What steps should be followed during the practice of EBHC?The steps of the process have been described in relation to evidence based medicine and the care of individual patients.25 I have adapted these steps to go beyond individual patient care and applied them to health care decisions in general. The steps are as follows:
The understanding and application of the basic principles of EBHC may help decision makers do the following:
The dangers associated with the practice of EBHC are likely to emerge from its misuse. Evidence can be abused by both patients and clinicians who may pay attention only to research evidence that supports their previously held views, overriding all contradicting evidence or other sources of information. Evidence can also be readily abused by politicians, policy makers, and third party payers who are more interested in financial stringency than improving health. If they ignore the fact that a lack of evidence of effectiveness is not the same as evidence of a lack of effectiveness, these politicians and third party payers may decide to pay only for those treatments supported by strong evidence in order to save money or increase profits. Evidence can also be abused by sensation-seeking journalists, who are interested in breakthroughs to make headlines, and therefore report only positive trials portraying them as the best available knowledge. The practice of EBHC can also become cult-like. Some decision makers may be willing to adhere to research evidence blindly, applying it in circumstances where it may not be appropriate, while ignoring its limitations, the role of other types of information, and the values and preferences of other decision makers. These dangers can easily be prevented by a proper understanding of the principles of EBHC outlined above. What barriers exist to the practice of EBHC? What are the most important barriers to EBHC from a decision maker's perspective? Despite the impressive efforts of the past 20 years to improve the use of evidence in decisions, most clinicians still face many barriers to the practice of EBHC. These barriers are shared by decision makers who lack clinical training (for example, consumers, journalists, planners) and are therefore more difficult to overcome. The existing barriers may not affect all decision makers in the same way or order. Among others, important barriers to the practice of EBHC from a decision maker's perspective include the following. Lack of awareness Some decision makers may not know about EBHC, and if they do they may have a poor understanding of it, and therefore do not realise its full benefits. Lack of time As a result of the existing reward systems and the increasing workloads of clinicians, the amount of time available to study and to keep up to date is likely to decrease rather than increase. Lack of motivation Some decision makers, even if aware of EBHC, may not feel motivated to practise it. This could be because they feel they do not have the skills or resources required to do it properly, or because they may be sceptical about the added value of the whole approach. Instead, these decision makers may decide to rely more on informal methods for decision making. Poor skills for question formulation Even if aware and motivated, some decision makers would fail to practise EBHC simply because they do not know how to formulate answerable questions that include all the elements described in Chapter 1. Inadequate literature searching skills and resources to access the literature Most training programmes in health care do not include formal courses and practical sessions to teach decision makers how to search the literature. Even if they do, decision makers are unlikely to have the time or motivation to maintain these skills and keep up with the developments in bibliographic databases. Many other decision makers may have the skills, but no access to sources of research evidence, namely computers, bibliographic databases, or even journals. Limited critical appraisal skills Few decision makers have received formal courses on critical appraisal and, even if they had, the effects of such courses are still unclear.24 Limited knowledge There might be limited knowledge about how to integrate research evidence with other types of information, values, preferences, and circumstances (see above). What are the most important barriers to EBHC emanating from the existing evidence?Even if decision makers have optimal skills to practise EBHC, they would face many barriers emanating from the current status of research evidence. Some of the most prominent evidence related barriers include the following. Abundance The amount of research evidence that is being produced in the world makes it impossible for any decision maker to keep up to date in isolation or, even more importantly, to find valid and clinically relevant material in the overwhelming body of literature. Poor internal validity (great risk for bias) Many studies, including RCTs, lack the methodological rigour required to produce unbiased results. The main sources of bias are described in detail in Chapters 3 and 4. Limited relevance Few studies are designed with the day to day needs of clinicians and patients in mind. Most RCTs, for instance, have placebo-controlled designs, which are good for meeting regulatory and academic needs, but inadequate for helping clinicians and patients to select treatments among many options that have never been compared directly. Most studies also lack clinician and patient input during the selection of outcome measures. For example, most RCTs lack measurements of quality of life, patient preferences, or the resource implications of interventions, and few last long enough to produce meaningful answers. Limited precision Most studies are too small to provide precise answers. What are the most important barriers to EBHC from the health care system's perspective?Typically, the most important barriers imposed by almost any health care system on earth include the following. Lack of financial incentives Clinicians' performance tends to be judged by the number of patients they see and the resources they generate, rather than by how much they study or strive to make decisions based on the best available evidence. Lack of training opportunities and effective training programmes There are few opportunities for clinicians to gain the skills required to practise EBHC. Even if more opportunities for training were available, the feasibility and effectiveness of the available teaching strategies have recently been questioned. A systematic review of 17 comparative studies, which examined the effects of different strategies on teaching critical appraisal to undergraduate medical students or residents, showed consistent gains in knowledge at the undergraduate level, but fairly small improvements in knowledge at the residency level.24 Surprisingly, these studies had methodological deficiencies that could have been easily prevented and that are often the focus of the criticisms of critical appraisers (for example, short duration, inadequate outcome measures, small sample sizes). The studies had other problems that were expected and more difficult to overcome, such as the lack of a culture for proper experimental studies of interventions targeting curricula, mismatch between the courses taught and the environments where the learners had to apply their skills, and a high risk of contamination.26 What can you do to overcome the limitations to the practice of EBHC? Free access to MEDLINE on the Internet Evidence based publications Specialised compendia of evidence for clinical practice Evidence based textbooks Specialised web sites The bottom line Health care decisions are the result of a complex and poorly understood interaction among many factors, of which research information (and RCTs in particular) is just one component. Other types of study designs and even anecdotes can provide valuable information on aspects of a decision that trials do not address. In addition, information alone is insufficient to make decisions. The values and preferences of the decision makers, and the circumstances in which decisions are made, often act as modulators of the information available to the decision makers and can sometimes even override it. There are major challenges to optimising the way in which decision makers use information and integrate it with their values and circumstances. Evidence based health care has evolved as a strong movement to accelerate this process. To succeed, however, we will require massive efforts and strong commitment by everyone involved in health care decisions to ensure that major barriers are overcome. The rapid development of information technology and international initiatives are providing unprecedented opportunities to overcome these barriers. References 1. Haynes RB, Sackett DL, Gray JRM, Cook DL, Guyatt GH. Transferring evidence from research into practice: 1. The role of clinical care research evidence in clinical decisions [editorial]. ACP J Club 1996;125:A-14; Evidence-based Medicine 1996;11:196-8. 2. Enkin M, Jadad AR. Using anecdotal information in evidence-based decision- making: heresy or necessity? In review 3. Sacks H, Chalmers TC, Smith H. Jr. Randomized versus historical controls for clinical trials. Am J Med 1982;72:233-40. 4. Altman, DG. Practical statistics for medical research, 1st edn. London. Chapman & Hall, 1991. 5. Streiner DL, Norman GR. PDQ epidemiology, 2nd edn. St Louis, MI: CV Mosby, 1996. 6. Guyatt GH, Sackett DL, Sinclair JC, Hayward RSA, Cook DJ, Cook RJ for the Evidence-Based Medicine Working Group. Users' guides to the medical literature. IX. A method for grading health care recommendations. JAMA 1995;274:1800-4. 7. Browman GP, Levine MN, Mohide EA, Hayward RSA, Pritchard KI, Gafni A, Laupacis A. The practice guidelines development cycle: a conceptual tool for practice guidelines development and implementation. J Clin Oncol 1995;13:502-12. 8. Jones R. Who does qualitative research? BMJ 1995;311:2. 9. Pope C, Mays N. Reaching the parts that other methods cannot reach: an introduction to qualitative methods in health and health services research. BMJ 1995;311:42-5. 10. Kuckelman-Cobb A, Nelson-Hagemaster J. Ten criteria for evaluating qualitative research proposals. J Nursing Educ 1987;26:138-43. 11. Nisbett RE, Ross L. Human inference: strategies and shortcomings of social judgment. Englewood Cliffs, NJ: Prentice-Hall, 1980. 12. Tversky A, Kahneman D. Judgment under uncertainty: heuristics and biases. Science 1974;185:1124-31. 13. Redelmeier DA, Rozin P, Kahneman D. Understanding patients' decisions: cognitive and emotional perspectives. JAMA 1993;270:72-6. 14. Borgida E, Nisbett RE. The differential impact of abstract vs. concrete information on decisions. J Appl Soc Psychol 1977;7:258-71. 15. Lomas J, Enkin M, Anderson GM, Hannah WJ, Vayda E, Singer J. Opinion leaders vs audit and feedback to implement practice guidelines. JAMA 1991;265:2202-7. 16. Jadad AR, Haynes RB. The Cochrane Collaboration—Advances and challenges in improving evidence-based decision making. Med Decision Making 1998;18:2-9. 17. Guyatt G, Rennie D. Users' guides to the medical literature. JAMA 1993;270:2096-7. 18. Atkins D, Kamerow D, Eisenberg GM. Evidence-based medicine at the Agency for Health Care Policy and Research. ACP Journal Club 1998;128:A-14-16. 19. Smith K. Evidence-based management in health care. In: Peckham M, Smith R, eds. Scientific basis of health service. London: BMJ Publishing Group, 1996;92-98. 20. Mulhall A. Nursing research and the evidence. Evidence-Based Nursing 1998;1:4-6. 21. Geddes J, Reynolds S, Streiner D, Szatmari P, Haynes B. Evidence-based practice in mental health. Evidence-Based Mental Health 1998;1:4-5. 22. O'Connor T, Meakes E. Hope in the midst of challenge: an evidence-based approach to pastoral care. J Pastoral Care 1998:52(4). 23. Gray JAM. Evidence-based healthcare: how to make health policy and management decisions. London: Churchill-Livingstone; 1997. 24. Norman GR, Shannon SI. Effectiveness of instruction in critical appraisal (evidence-based medicine) skills: a critical appraisal. Can Med Assoc J 158:177-81. 25. Sackett DL, Richardson WS, Rosenberg W, Haynes RB. Evidence-based medicine: How to practice and teach EBM. New York: Churchill Livingstone, 1997. 26. Sackett DL, Parkes J. Teaching critical appraisal: no quick fixes. Can Med Assoc J 1998;158:203-4. 27. Haynes RB, Jadad AR, Hunt DL. What's up in medical informatics? Can Med Assoc J 1997;175:1718-19.
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