And generally, let this be a rule, that all partitions of knowledge be accepted rather for lines and veins than for sections and separations; and that the continuance and entireness of knowledge be preserved. For the contrary hereof hath made particular sciences to become barren, shallow, and erroneous, while they have not been maintained from the common fountain.
— Francis Bacon51
Medical knowledge is itself an element of the health care system. Just as the system fails to organize health care providers for delivering patient-centered care, so it fails organize medical knowledge for solving the medical problems of unique individuals. Instead, knowledge is organized for comprehension by the unaided minds of physicians. Medical specialties, for example, are defined by body system, because that narrowing of focus reduces the burden of comprehension. Yet, patient problems normally implicate multiple body systems. Similarly, because the mind more readily comprehends generalities about large populations than detailed data about individual variation, evidence-based medicine is oriented towards population-based forms of evidence that poorly describe the realities of unique individuals. Indeed, that orientation characterizes medical knowledge in general.
The reality is that every individual is a unique combination of resemblances to and differences from other individuals. Medical knowledge is oriented towards the resemblances, not the differences. All diabetics, for example, have in common some dysfunction in hormonal regulation of blood glucose levels; indeed, diabetes is defined in terms of that resemblance. Of course, diabetics vary enormously in how the disease occurs, in the circumstances (physiological, psychological, social, economic) of its occurrence, and in the actions needed to manage the disease over time. Some of these variations are specific to the individual, while others occur across definable subpopulations, which include broad groupings (e.g., Type I and Type II diabetics) to narrower ones (e.g., Type I diabetics with chronic renal insufficiency and cardiovascular disease). Each individual diabetic is a unique and changing combination of some resemblances to some subpopulations, plus some variations specific to the individual. Multiple dimensions of this uniqueness must be taken into account to manage diabetes over time.
Medical knowledge about diabetes is oriented towards resemblances among individuals within subpopulations. A great deal of medical knowledge about these interrelationships has been accumulated. Much more such knowledge about diabetes remains to be discovered. This illustrates the vital role of population-based analysis employed by scholars of evidence-based medicine. But that role is crippled by failure to use the external tools—and corresponding standards of care—necessary to perceive and document medical realities encountered every day in diabetic patients. Those are the very same tools and standards that caregivers and patients need for their daily functioning. Were they consistently employed—that is, if more patient care took place in Popper’s World 3 rather than World 2—then new knowledge and errors in existing knowledge would constantly be coming to light.
Medical knowledge long ago exceeded what the unaided mind is able to take into account or integrate with corresponding patient data (not to mention additional data about variations specific to the individual). Were the missing standards and tools to be enforced in patient care, then the simultaneous use and development of knowledge could generate enormous synergies. Health care cost and quality could become an arena of continuous improvement, rather than a quagmire of intractable dilemmas.
Even now, with medical practice still mired in the status quo, science is transforming medical knowledge. New understanding of disease at the genetic and molecular level is already making it possible to reconceive existing diagnostic entities and classifications. These advances in medical science, however, demand a comparable transformation in medical practice. To reiterate, more complete, organized, documented clinical observations in patient care, plus better linkages among these observations and existing knowledge of disease and therapy, would yield constant feedback on that knowledge. There is reason to believe that we would learn how seemingly distinct disease conditions may actually be interrelated, how medical interventions that seem narrowly targeted at a specific gene or molecular pathway may actually disrupt multiple body systems, of how an individual’s phenotype may actually be more important than genotype for some diagnostic and therapeutic purposes, and how drugs and other powerful interventions sometimes may be more disruptive and less effective therapeutically than simple improvements in health behaviors. These possibilities are reinforced by evidence that common disease conditions appear linked to many rare genetic variants among individuals rather than to a few common variants across populations.52 Thus, individual heterogeneity and uniqueness, no less than patterns of resemblance across populations, must become the subject matter of medical knowledge.