In theory, practice and theory are the same. In practice, they are not. Evidence-based practice has gained prominence over more theoretical approaches in several areas, particularly in the field of health care. Theory-guided and evidence-based practice share the common goal of making the right decision and finding the most effective solution for a perceived problem. However, they have some core philosophical differences.
At its core, the divide between evidence-based practice and theory-guided practice can be traced back to an ancient divide often found in science and philosophy: That of rationalism versus empiricism. Extreme rationalists claim that our senses are limited and place all their trust in reason. In contrast, empiricists claim that sense experience is the source of all our concepts and knowledge. While their positions are not so extreme, theory-guided practice follows a rather rationalist approach, while evidence-based practice favours empirical knowledge.
The movement for evidence-based practice gained momentum during the 1970s, when A.L. Cochrane drew attention to the lack of solid information about the effects of health care. A series of studies about the percentage of health care based on high-quality evidence concluded it ranged from 10% to 25%. The rest of the time, decisions were taken on the basis of the judgement of experts. In response, Cochrane emphasised the need for health professionals to base their interventions and activities on the most up-to-date evidence or knowledge available, taking the randomised controlled trial as the golden standard of evidence. In contrast, statements by the "medical expert" are considered to be the least valid form of evidence unless the pronouncements are backed by scientific studies.
Because experts often have differing opinions, expert-guided treatments can vary illogically from clinician to clinician or from place to place, for patients with the same condition. The effect of evidence based practice is standardising health care practices using science and the best evidence available. The net effect is a reduction of what the Institute of Medicine calls the "quality chasm"--the gap between what is known to be the best health care, and what is actually practised.
The randomised controlled trial is the golden standard of evidence-based practice. Sometimes, the practitioner will face a predicament for which no such trials have been performed previously. Randomised controlled trials may actually be infeasible or undesirable for some particular conditions or situations because of their rarity or severity. In those situations, a theoretical approach may be appropriate. Besides , some crucial dimensions of practice, like ethics and values, are impossible to quantify. That is why even during the boom in popularity of evidence-based practice there are practitioners like Carold Picard and Elizabeth Henneman, from the University of Massachusetts, who call for nursing education and practice to be theory-guided, so that nurses live out the values and philosophy that underpin nursing theories.
It must be noted that theory and evidence are not at all incompatible, and there is ample literature about theory-guided evidence-based practices that incorporate both."Good doctors use both individual clinical expertise and the best available external evidence, and neither alone is enough", explained David Sackett, pioneer of evidence-based medicine. "Without clinical expertise, practice risks becoming tyrannised by evidence, for even excellent external evidence may be inapplicable to or inappropriate for an individual patient. Without current best evidence, practice risks becoming rapidly out of date, to the detriment of patients."