Clinical decision making: sine qua non of the curriculum.

Send the patient to radiology or not? MRI or arthrography for the TMJ? E-speed or D-speed film? Panoramic plus bitewings or a full-mouth series? CT or tomography for implants? Is it apical osteitis or periapical cemental dysplasia? Is it inflammation or malignancy? These are just a few of the many questions and decisions that we encounter every day in clinical radiology. By and large, the basic science and traditional clinical curricula prepare us to ask the questions and understand the issues at hand, but leave us ill prepared to answer and address them. Unfortunately, clinical practice is often based on rote memorization of 'recipes' learned in school or residency, or on intuition, heuristics and folklore. This no longer need be. Practitioners now have an alternative, our own 'basic science' clinical decision making. For many, clinical decision making conjures up flow diagrams and algorithms; diagnostic efficacy; riskbenefit and cost-effectiveness analyses; technology assessment; and decision analysis. Clinical decision making uses all of these tools, but is not defined by them. Decision making blends mathematics, biostatistics, epidemiology and the 'scientific method' into a rational, systematic and defensible method of making decisions about health policy and individual patient care. In health care we have many choices. This is especially true in radiology, where the choices are often high-tech and costly. Dr Samuel O. Thier, then President of the Institute of Medicine of the US National Academy of Science, addressed this issue at the 68th Annual Session of the American Association of Dental Schools'. He said, 'Practices are built by accretion rather than by assessment. We no longer know which of the available choices in a given circumstance is best relative to the others. We only know whether something works or does not. That is an unacceptable situation for any of the professions, and particularly unacceptable in health services where costs keep rising. If we cannot determine what is useful and what is appropriate, then it is unlikely that we will make wise choices about what we wish to do.' One of the important concepts of clinical decision making is that 'we' includes the patient. Patients manifest disease differently, have different risk thresholds, and value infirmity and mortality differently. The best choice for one patient with a given problem may not be the best for another with the identical problem; the patients are different. Clinical decision making recognizes that there are often several correct answers, and which is most correct changes with changing information or circumstances. The many successes of reductionist, mechanistic basic sciences (for example, specific antibiotics for specific microbial infections, and the identification of a specific gene alteration for sickle cell anaemia) may lead one to believe that there is a single path for solving all problems or answering all questions. Not so. Just as Newtonian physics was superseded by quantum mechanics, deterministic pathobiology will be replaced in many instances by probabilistic clinical decision making. None the less, decision making is not a panacea. Formal clinical decision making is limited in many instances by the lack of appropriate databases. This point was emphasized repeatedly during the 'Clinical Decision-Making in Dentistrt symposium recently held in Seattle, Washington. A unifying theme of the various presentations was that the current status of formal clinical decision making, especially decision analysis, may be summarized as 'The medium is the message'. Even when the numerical analysis is impossible to perform, the statement of the problem in formal decision-making terms (for example, a decision tree) involves a thinking process that is itself likely to improve the decision. Fortunately, the databases in radiology, while still incomplete, are better than what is available in other dental disciplines. This means quantitative, probabilistic clinical decision making can be, and should be, incorporated into the everyday practice of clinical radiology. This may be a struggle since, as John Allan Paulos notes, 'Innumeracy, an inability to deal comfortably with the fundamental notions of number and chance, plagues far too many otherwise knowledgeable citizens'>, And what of our otherwise knowledgeable students and practitioners? Increases in quantity and sophistication of knowledge have outstripped our ability to keep up, and require changes in how we teach our students and practice our profession. Dr Derek Bok,