Historicizing Evidence-Based Medicine: “Population Thinking” in the Clinic

1. Historicizing Evidence-Based Medicine:“Population Thinking” in the Clinic J. Rosser Matthews University of Maryland September 24, 2009

2. EBM Working Group (1992) • “Evidence-based medicine de-emphasizes intuition, unsystematic clinical experience, and pathophysiologic rationale as sufficient grounds for clinical decision making and stresses the examination of evidence from clinical research.”

3. Focus on individual (clinical perspective) Deterministic reasoning Realism (seek underlying causes) Focus on group (public health perspective) Stochastic/probabilistic reasoning Empiricism (focus on what can be directly measured) Contrasting Visions of Medical Science

4. Overview of Presentation • Individual v. Group: “Numerical Method” in 19th century Paris clinic • Determinism: Claude Bernard & 19th century physiology • Realism v. Empiricism: Almroth Wright v. Biometricians • EBM: Debates echo all three dichotomies

5. Paris Medicine • Rise of pathological anatomy as revealed through autopsy • Hospital setting provides opportunities to view thousands of patients • Replace listening to the patient’s “story” with physical examination • Use of the “numerical method” to evaluate therapy

6. Louis on Numerical Method (1835) • “We shall hear no more of medical tact, of a kind of divining power of physicians . . . But an analysis of a more of less extensive series of exact, detailed facts; to the end that answers may be furnished to all possible questions: and then, and not till then, can therapeutics become a science.”

7. Academy of Sciences Report (1835) • “In the field of statistics . . . the first task is to lose sight of the individual seen in isolation, to consider him only as a fraction of the species. He must be stripped of his individuality so as to eliminate anything accidental that this individuality might introduce into the issue at hand. In applied medicine, on the contrary, the problem is always individual, facts to which a solution must be found only present themselves one by one; it is always the patient's individual personality that is in question, and in the end it is always a single man with all his idiosyncrasies that the physician must treat. For us, the masses are quite irrelevant to the issue.”

8. Bernard on Taking Averages (1865) • “Let us assume that a physician collects a great many individual observations of a disease and that he makes an average description of symptoms observed in the individual cases; he will thus have a description that will never be matched in nature. So in physiology, we must never make average descriptions of experiments, because the true relations of phenomena disappear in the average; when dealing with complex and variable experiments, we must study their various circumstances, and then present our most perfect experiment as a type, which, however, still stands for true facts. In the cases just considered, averages must therefore be rejected, because they confuse, while aiming to unify, and distort while aiming to simplify.”

9. Wright Crucial Experiment Cumulative Experiment Experiential Method Statistical Method Greenwood Statistical Method Experiential Method “Crucial Experiment”—non-existent Evidentiary Hierarchies (1912/1913)

10. Contemporary Issues for EBM • Internal v. External Validity of Clinical Trials • Heterogeneity of Treatment Effects • “Statistician as dictator”

11. We have come full circle to faith-based medicine. We are encouraged and, even, forced to mold our practice of medicine to the authority of those practitioners of EBM that are ‘approved’ and ‘acceptable’ . . . It has become the antithesis of populism. It has created its own system of belief to which we have to practise faith-based medicine (2004) “The wheel has come full circle, and . . . the programme of abolishing in every branch of science the despotism of the expert–has ended in the setting up the statistician as dictator wherever in any part of the field of knowledge the method of cumulative experiment comes into application.” Wright (1912) “Statistician as Dictator”

12. Assessing EBM Historically • A new paradigm? • Old Wine in New Bottles? • Mirror-Image Twins (Edwin Layton) • The end of Medicine’s “Golden Age” • Introducing “society” into the clinical encounter • Opening a Pandora’s Box