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Commentary |
University of Dundee, Department of Surgery and Molecular Oncology, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK
"It is the duty and virtue of all knowledge to abridge the infinity of individual experience" [1].
Just under 50 years ago, when J K Galbraith coined the phrase "The conventional wisdom", he was defining "the ideas which are esteemed at any time for their acceptability" [2]. His intention was to point out that there may be important differences between what is acceptable, the territory of the conventional wisdom, and what is true. For clinicians, the current conventional wisdom is that clinical practice must be evidence based and that randomized controlled trials provide the best evidence upon which to base practice [3]. As a result we are supposed to judge articles in medical journals according to a hierarchy of research designs, a hierarchy headed by randomized clinical trials (RCTs) and systematic reviews [4, 5]. In this world-view, observational studies and accounts of accumulated clinical experience are considered to be neither of merit nor of interest, and so, according to the conventional wisdom, they are not usually worth publishing. So why does this issue of the BJR contain a paper by El Hamri and colleagues [6] which is simply a review of the experience at one institution, St Bartholomew's Hospital, with one technique, stereotactic radiosurgery?
Galbraith's comments on the conventional wisdom apply neatly to evidence based medicine [3] in its more dogmatic incarnations.
"...the accepted ideas become increasingly elaborate. They have a large literature, even a mystique... ...the very vigour of minor debate makes it possible to exclude as irrelevant... any challenge to the framework itself... ...the conventional wisdom often makes vigorous advocacy of originality a substitute for originality itself.... ....deviation in the form of originality is condemned as faithlessness or backsliding... ...expounding the conventional wisdom is both necessary for, and a prerogative of, success..."
However, the conventional wisdom is not necessarily true and we should always approach it with that healthy scepticism that is an essential component of scientific practice. One final comment from Galbraith: "the enemy of the conventional wisdom is not ideas but the march of events..." [2]. It seems, therefore, both pertinent and legitimate to ask whether or not the concept of a hierarchy of evidence will remain valid, or are events marching?
There is an increasing realisation that the issues that can be dealt with by RCTs are limited – by restriction (to certain groups of patients, or to specific types of intervention) and by level of detail (generic issues are adequately covered, but the particular cannot be accommodated) [7, 8]. Since clinical practice involves helping individual patients to make individually appropriate decisions, even when the evidence is available, we have difficulty incorporating the evidence from randomized controlled trials into our everyday practice. Simple questions from acute general medicine ("should patients with uncomplicated myocardial infarction be routinely treated with Warfarin?") are far more amenable to an evidence-based approach than more complex questions involving patients with chronic diseases ("does chemotherapy improve both quality of life and survival in patients with inoperable non-small cell lung cancer?"). We measure that which is easy to measure – survival. We find it far more difficult to measure a person's comfort, hopes and expectations, and so we have little or no evidence concerning the effects of chemotherapy on these important aspects of life. The position is even more difficult when we consider evidence-based radiation oncology. Radiotherapy is both a complex intervention and an evolving technology. Expertise-based randomization [9] is, at best, only a partial solution to these problems. Results from randomized trials using obsolete technologies can be no guide to current practice [10].
I am not advocating that we abandon the appropriate use of randomized trials, nor would I argue for a clinical practice based entirely on a mixture of anecdote, custom and personal whim. I would simply point out that there are important activities in clinical research that are neither randomized nor systematic, nor hopelessly anecdotal: to borrow an expression from sociology, we may speak of "activities of the middle range" [11]. Activities of the middle range are those that form a bridge between the general, as epitomised by randomized controlled trials and systematic reviews, and the particular, such as case reports and anecdotes. The idea that activities (and theories) of the middle range are worthy in their own right is, of course, not new. Francis Bacon was acutely aware of the importance of such activity and mischievously misquoted Plato in support of his argument: "And Plato in his Theaetatus noteth well, That particulars are infinite, and the higher generalities give no sufficient direction: and that the pith of all sciences, which maketh the artsman different from the inexpert, is in the middle propositions, which in every particular knowledge are taken from tradition and experience" [1] {XIII.2} p150. Hogarth took a middle range approach to the aesthetics of representative art [12]. George Orwell's journalism was an activity of the middle range, but was his journalism in any way inferior to his novels? Is West Side Story a lesser work than the Chichester Psalms? The 300 (or so) cantatas that Bach wrote for the Thomasschule were liturgically demanded, rather than divinely inspired, but that in no way diminishes their beauty or importance. Lofty purpose does not always imply high achievement, nor are everyday tasks devoid of value.
The problem we face as providers and consumers of clinical research is that the use of the concept of a hierarchy of evidence has inappropriately diminished the importance of activities of the middle range [13]. Somehow we have convinced ourselves that the talismanic words "randomized" and "systematic" are guarantees of scientific worth and that any activity to which the word "observation" is attached is of dubious merit and that the adjective "mere" should be automatically attached to it.
Observation is now, and always has been, crucial for medical progress. We need observational studies for a variety of reasons:
We ignore the fact that bad research is bad research, whether randomized or observational, and that the opposite is also true. If research based on observation has a bad name, this is a consequence of the way the research is usually carried out and reported. Many observational studies are badly designed and reported and it is extremely difficult to draw any worthwhile conclusions from them, even in aggregate [14]. This is a failure of implementation rather than a fundamental and ineluctable flaw in the approach itself. We need to set, and to achieve, higher standards in observational research. Randomized trials have their CONSORT (Consolidated Standards of Reporting for Trials) statement [15, 16], systematic reviews have their QUOROM (Quality of Reporting of Meta-analyses) statement [17]. We need similar standards for observational studies. Fortunately, such standards are now emerging for studies in epidemiology and public health [18, 19], for studies of diagnostic tests (STARD: Standards for Reporting of Diagnostic Accuracy) [20–22], and for studies of prognostic factors [23–25]. These standards should be of use and interest to both contributors and readers of the BJR.
Events overtake the conventional wisdom. Well-conducted observational research is likely to replace randomized trials as the engine of clinical progress. We are on a cusp: looking backwards towards randomized trials; looking forwards to a world of personalized medicine. A world in which we meticulously observe each individual patient, accumulating large amounts of data, and then combine the power of informatics with clinical experience to establish the optimal management for that individual. The RCT is to clinical investigation as the bicycle is to transport. We needed randomized trials because we could neither identify nor handle important confounding variables. As methods for acquiring, handling and relating data improve, we will be able to identify confounders and randomized trials will become a less important source of evidence upon which to base decisions. It is a pleasant irony to consider that increasing scientific sophistication, in molecular biology and computing will move us away from mindlessly accruing subjects for clinical trials and put clinical medicine back where it has always belonged; with the individual human being. We shall harness the power of science to put the humanity back into clinical practice. In the meantime, we should continue to report upon, and to publish, well-conducted observational studies. We should neither apologise for, nor deprecate, the activities of the middle range. It is in this spirit that we publish the article by El Hamri et al [6].
"The reality of much clinical research is that the starting point is a series of observations in which the astute clinical observer notices something exceptional" [26].
Received for publication February 1, 2005. Accepted for publication February 17, 2005.
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