1. Changing conceptual models of medicine
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Selected topics in the history of Medicine are covered in a series of lectures in the first year SIM curriculum. These include an introduction to the profession of medicine in the Introduction Unit, a lecture on William Harvey's discovery of blood circulation in Foundations, and a lecture on Tuberculosis in Unit 1.
Various other SIM sessions refer to historical themes and this page assembles some of these topics. You will also find a number of brief biographic sketches of important historical figures and events, in the Humanities content of the weekly CBL cases.
Our thinking about health and disease have evolved over the past hundred years.
The medical model highlights disease, a crucial issue facing society, and disease states are readily diagnosed and counted. But this approach is narrow, viewing health principally in terms of physical disease and function. In extreme form it implies that people with disabilities are "unhealthy". A further potential limitation is the omission of a time dimension. Should we consider as equally healthy two people in equal functional status, one of whom is carrying a fatal gene that will lead to early death? Further, if prognosis is not included, there is no virtue in prevention.
The holistic and wellness models have the advantages of discriminating among people at the higher end of functioning; they focus on mental as well as physical health and on broader issues of quality of life. They also allow for more subtle discrimination of people who succeed in living productive lives despite a physical impairment: blind people or amputees may still be able to satisfy aspirations, be productive, happy and so be viewed as healthy. The disadvantage is that these conceptions run the risk of excessive breadth, of incorporating all of life within the health system. Thus, they do not distinguish clearly between the state of being healthy and the consequences of being healthy. A further challenge is that by espousing a dynamic model of health (e.g., the capacity to rally from insults), healthiness predicts itself. Hence, we must also move from a strictly linear model of cause and effect toward a systems model in which health is a force, both input and output, and not merely an output of a linear process.
Human society is based on ideas; they inform and shape all of our actions.
One hundred years ago, at the turn of the twentieth century, the great Dr. William Osler was Regius Professor of Medicine at Oxford University. He was a preeminent teacher who emphasized bedside clinical teaching; he viewed disease as a puzzle to be solved by the use of the clinician’s five senses, his knowledge of pathology and his deductive powers. The diagnosis was to reflect the pathological process that accounted for the signs and symptoms. In Osler’s mind the clinical questions were simple: "What disease does the patient have?" And, "How do I treat it?" Actually, the patient was somewhat incidental, basically a representative of the class of people with this disease. Biological individuality was disregarded. Osler was an activist; he saw the patient as a broken machine that needed to be fixed, and his role was to show the world how to fix illness.
Osler was succeeded as Professor of Medicine by Archibald Garrod; there could hardly have been a starker contrast. Osler taught how to treat disease; Garrod taught how to think about diseases and why they exist. For Garrod, individuality was a crucial element in any diagnosis and treatment. He was interested in questions such as "Why did this person get this disease, and why at this time?" And, "What can I do to restore this person’s orientation to his environment?" Garrod studied the chemical individuality of people, including inborn errors of metabolism. He saw this variability as crucially important, for from variability spring the raw materials for natural selection. Garrod was a contemplative man who saw the patient not as a broken machine, but as a consequence of the encounter of a unique individual with an environment for which he was not perfectly suited.
Two models of medicine. The prevailing metaphor of Western medicine continues to view the body as a machine which the doctor is called on to fix when it breaks. (See allopathic medicine). Medicine as engineering: doctors using technology to practical ends. The gold standard for success is cure; improvement is good, but only as a step on the road to cure. Science hunts for cures for diseases not yet understood. Lewis Thomas wrote "Disease comes as a result of biological mistakes" and "I cannot imagine any category of human disease that we are precluded from thinking our way around." The goals of medicine are to apply the theoretical knowledge of the basic medical sciences to relieve pain, to prevent disability and to postpone death. In today’s terms, by knowing the sequence of the base pairs of the genome we shall advance toward our goal of achieving a complete understanding of the biology of disease.
Fast forward to the end of the twentieth century, when cracks had appeared in the engineering approach to medicine. Not only are high-tech diagnostic and curative efforts increasingly costly, but specialization takes us ever further from the ideal of preventing disease in the first place. Because of the impossibility of learning all the facts, medical specialties break down into finer and finer sub-disciplines that focus on ever narrower pieces of the patient. In such a context, how do we maintain an awareness of the identity and human qualities of the patient? The mechanical metaphor fails to answer questions such as:
Of course, the engineer views such questions as metaphysical and irrelevant, but if we do not contemplate them we are destined to limit ourselves to developing ever more complex technical approaches to fixing problems that likely could be anticipated before they arise. Perhaps we need a new outlook that asks why diseases occur at all, what forms they take, and how we may re-orient our approach to an anticipatory, rather than a reactive, one.
Our science directs our attention ever more finely onto how things go wrong: from patient to organ, to cell, to molecule. We do not look the other way, to examine how things go right, from the individual to their family, to the environment and to evolution itself. Evolution proceeds by descent with modifications over time; the fate of individuals depends on their adaptation to the environments they meet. This returns us to variation between individuals, for if the species is to survive through changing environments there must be a stock of diversity from which to choose. In this view, individual variation represents a crucial resource for future evolution of an imperfect organism and not, as the engineering model suggests, errors from the perfect blueprint. There is, indeed, a conflict between a theological view of Man as a perfect creation, and a Darwinian view of man as a work-in-progress. Sometimes, this diversity brings the individual into conflict with their environment, and disease results. Hence, disease can be viewed as a mis-match between the person and their environment, not as a broken machine. Disease may be as much a symptom of a bad environment as of a broken person; management may entail adapting the environment as logically as fixing the individual (give people better houses!).
The doctor’s role is to conserve the individual and restoration of balance; this approach is far more tolerant of prevention than is the engineering conception. This contrast between the engineering and the natural history or adaptational views reflect contrasting approaches to science:
The demographic structure and the patterns of disease in a population exert a profound mutual influence on each other. The age structure, the genetic and and ethnic make-up of a population affect the types of disease that will be seen, while the types of fatal condition seen affect survival at different ages, and hence the demographic structure. Both are influenced by history and geography, as fundamental determinants.
The demographic transition: the trend from high birth and death rates toward reduced death rates, hence longer survival, followed by reduced birth rates.
You can see a dynamic population pyramid for Canada, running from 1901 to 2001 here.
The evolving world population figures in real time from "Worldometers"
Of course, health is linked to wealth, and the transitions above also reflect improvements in our living environment brought about by changes in production, the economy and wealth.
Professor Hans Rosling and his Gapminder presentations give a wonderful summary of historical changes in health. Here is a chart showing the rising life expectancy from 1800 to 2015, for 150 countries, plotted against increasing wealth over the same period.
Infectious disease mortality decreased rapidly through much of the 20th century, until around 1980 when a significant turn-around began to occur. Between 1980 and 1992 the death rate from infectious diseases in the USA increased by 58% (this figure refers to people for whom the primary cause of death was an infectious disease). Since then we have become increasingly nervous about the possibility of a new pandemic, and the importance of public health measures is widely recognized.
It is easy to be over-confident about medical advances; infectious agents are diverse, can travel and mutate, and will always challenge our defences against them. The issue mirrors the ecological challenges posed by zebra mussels, spruce budworms and other beetles that continually threaten plant species. We should never forget the potential dangers: the influenza pandemic of 1918 and 1919 killed more than 20 million people worldwide (including 500,000 in the U.S.). More than all of the wars in the century.
In the years of optimism following World War II, many believed that humans were winning the long war against infectious microbes. Antibiotics could cure bacterial diseases such as TB and typhoid fever. Diseases of childhood such as polio, whooping cough, and diphtheria could be conquered through vaccination. Coupled with earlier improvements in urban sanitation and water quality, vaccines and antibiotics dramatically lowered the incidence of infectious diseases. It became plausible to imagine a world in which infectious pathogens would no longer prey on humanity.
As it turned out, the optimism was premature:
CDC web site on Emerging Infectious Diseases ("EIDs").
Tuberculosis is a disease that predates man, having long been present in animal species. Hippocrates (460 - 377 BCE) called it "phtisis" meaning to melt and waste away. Since then it received many names: "The white plague", "consumption"; "scrofula" (referring to inflammation of the lymph nodes) or "the King's evil".
TB rose to epidemic levels as a side-effect of industrialisation and the consequent urban crowding of poor people flooding into cities in search of paid employment in the nineteenth century. It has been estimated that 50% of all children born in cities in the early 1800s died before the age of two, and of these a third died from TB. The 1880 death rate from TB in Montreal and Toronto was estimated at 2 per thousand population (Katherine McCuaig "The weariness, the fever, and the fret" McGill-Queen's University Press, 1999).
As with many diseases, TB was declining long before the causative agent or effective medical therapy was invented.
Koch proved that the tubercle bacillus was the causative agent in 1882, but the decline in mortality had begun much earlier, due mainly to general improvements in sanitation and housing quality: non-specific health protective measures.
Note that effective therapy was not developed until 1944, with the invention of streptomycin. Until then treatment had consisted mainly of conservative medical measures: rest, fresh air, good nutrition. Survival was around 50% at five years.
(From WHO, Teacher's guide for basic epidemiology, 1993)
This illustrates of the impact of simple public health measures, even when specific treatments are not feasible. Similar patterns have occurred for measles, and this stresses the importance of containment and preventive measures for conditions such as respiratory conditions and HIV/AIDS.
Another lesson was that attitudes are slow to change. Despite the proof of infectious transmission from person to person, many physicians remained convinced that TB was an inherited disease "due to inherited constitutional peculiarities, perverted tumors and various types of inflammation" (Katherine McCuaig "The weariness, the fever, and the fret" McGill-Queen's University Press, 1999).
The efforts to counter the disease also led to many reform ventures, seeking to redesign cities, to educate the public and to change habits, that are comparable to some of today's efforts to tackle our contemporary obesity epidemic. The Canadian Association for the Prevention of Consumption and Other Forms of Tuberculosis held its inaugural meeting in 1901. The City Improvement Society was at work in Hamilton in 1903. Numerous women's groups worked hard to establish sanatoria for impoverished victims of the disease. Habits such as spitting had to be discouraged; disposable drinking cups became popular. Dust was especially targeted as it was considered a way that the disease could be spread. Streets were sprinkled with water, and damp sawdust spread on floors in public rooms. Social reformers, some with religiously-inspired zeal, made the connection with alcohol, on the basis that alcoholism led to poverty, which led to overcrowding, increasing the risk of TB transmission. "L'alcoolisme fait le lit de la tuberculose". This link also enabled the prohibition movement to gain a scientific basis for its work.
Dr Alan Brown, Sick Kids hospital pioneer on pasteurization of milk.
Updated August 3, 2017