Evidence Based Medicine: editors' overview and introduction

Although its roots can be found in the late 19th century, and although it draws heavily on work in clinical epidemiology that dates from the 1960s, evidence-based medicine (EBM) is still a young discipline (Sackett 2002). In 1992, the Evidence-Based Medicine Working Group, based primarily at McMaster University in Ontario, Canada, announced "a new paradigm" of medical practice. Initially, the goal of EBM was to teach medical students and physicians to search and critically evaluate the medical literature pertaining to specific clinical questions. Since that time, EBM has instead come to be associated primarily with the production of secondary resources that "digest and summarize" the medical literature for clinicians (Upshur, VanDenKerkhof, and Goel 2001). What has remained, however, is an emphasis on the potential of clinical research to inform and improve clinical decision making.

For several reasons, it is now timely to review the successes and problems of EBM. First, EBM has grown to become a large and influential movement. Groups such as the National Guideline Clearinghouse in the United States and the international Cochrane Collaboration use the evidence hierarchy of EBM to produce guidelines and summaries that guide clinical practice globally. The EBM approach influences research funding and publication decisions, as well as patient care. Moreover, EBM's sphere of influence has expanded far beyond its origins in internal medicine: there are now resources available for evidence-based nursing, dentistry, veterinary care, hospital management, social services, and public policy, and the list grows longer. (There have even been ambitious suggestions of evidence-based politics.) Medicine, then, is the first testing ground of evidence-based practice more generally. Evidence-based practice, in various forms, is shaping decisions that affect the health and well-being of billions of people, and this new approach to decision making is likely to have significant implications. Careful attention to EBM is vital if we are ever to assess the efficacy and effectiveness of evidence-based practice. Finally, the limitations as well as the strengths of the EBM approach are becoming increasingly clear. EBM is often criticized for not adequately addressing the difficulties that arise in utilizing its guidelines in the care of individual patients. Further, critics charge that the emphasis on randomized controlled trials in the EBM hierarchy of evidence means that other important sources of evidence are being ignored. These critiques, among others, raise issues about the assumptions and implications of EBM and indicate the need for further discussion.

The basic message of EBM, that medical practice should be informed by the results of relevant research, is valuable and worth preserving. Important work remains to be done, however, to figure out how best to implement this message. The essays in this issue of Perspectives in Biology and Medicine address ways in which EBM practices might be modified to provide a better knowledge base for medicine, the ethical issues in the application of EBM guidelines to individual patients, and problems in the extension of EBM to public health practices. Although many of these papers are critical of EBM, their criticism is for the most part constructive. We hope that these essays will contribute to a broader discussion of the ways in which EBM might be refined so that it can make an even more effective contribution to the improvement of health care.