Recordando a McKeown..que salubrista....

The McKeown thesis

Bill Bynum a

Geriatricians might be forgiven for thinking that the McKeown thesis is about bed blocking. Thomas McKeown did an important early study in the 1950s of elderly patients in Birmingham hospitals, in the UK, who didn't need hospital care but had no place to go. For historians, those involved with public health and anyone concerned with the wider role of medicine, however, the name McKeown points towards a historical thesis about the role of curative medicine in the collective mortality gains during the past two centuries.

McKeown (1912—88) spent most of his career as professor of social medicine at the University of Birmingham. He got the chair (1945) in this new field because he had impressed the appointment committee the previous year when he had applied for the chair of anatomy. Born in Northern Ireland, where both of his parents were officers in the Salvation Army, he spent his childhood in Canada, training in medicine at McGill. Returning to the UK as a Rhodes Scholar, he continued his research interests in physiology. After 1945, the wider social dimensions of medicine became his brief.

The McKeown thesis dates from 1955, when he and a colleague R G Brown, published a paper in Population Studies, evaluating the relation of medicine to the rise of British population from the late 18th century. The 1760s saw the beginning of the modern demographic regime, where human population growth has been sustained, beginning throughout Europe and North America and eventually embracing the whole world. McKeown and Brown wrote in a golden age of medicine, when the sulpha drugs, penicillin, streptomycin, cortisone, other pharmaceuticals, and new therapies had created a period of postwar optimism in the power of medicine to abolish the major historical scourges of humanity, the infectious diseases. This optimism had coloured historical interpretations of the effectiveness of medicine since the 1750s, when hospitals, medical education, and medical sciences began to emerge in modern dress. Starting with the indisputable fact that population growth had occurred throughout western countries, with different timing and rates of increase, McKeown and Brown questioned the part medicine had played in this phenomenon.

Populations in a given area increase for only three reasons: more people are born, fewer die, or immigration occurs, or some combination of the three. These are the reasons, but they are not the cause. Since McKeown and Brown confined themselves to the British population at the beginning of the upward population curve, in about 1760, they felt able to exclude immigration. They argued that in the absence of birth control, fertility was also at its highest, and in any case, larger family size in fairly undeveloped societies increases childhood mortality, since mothers have less time to devote to each child and the children become more exposed to communicable diseases. Adopting the method of Sherlock Holmes, they eliminated the impossible, and what was left was the answer: decline in mortality.

They then turned their Holmesian method on the possible causes of this decline. To the obvious answer that it must be the result of better medical therapeutics, advances in medical knowledge, and more hospitals, they issued a resounding “No”. Doctors had virtually no effective drugs at their disposal, and pre-Listerian surgery was barbaric and frequently led to death from sepsis or shock. Further, hospitals were places to which people went only as a last resort. They were known even then as “gateways to death”, as patients often died of hospital-acquired infections (and the vigorous misdirected attentions of doctors). Doctors were constantly learning new anatomy and physiology, but these attainments did not translate into more effective therapeutics. The natural philosopher Francis Bacon (1561—1626) had once written “Knowledge is power”; in the healing arts, the equation did not always obtain.

McKeown always acknowledged the importance of vaccination after 1798, although he was less sanguine about the effectiveness of the earlier practice of inoculation with the smallpox virus. Smallpox vaccination remained for him the unequivocal triumph of medical intervention in the early period. Admirable as it was, it could not by itself account for the 18th-century population rise. By their process of elimination, he and Brown concluded that the cause must be looked for outside of medicine and the medical profession.

This little paper launched McKeown on his major life's work. Although his general question remained “Why have populations increased?”, his subtext was “Has medicine mattered?”. In the 1960s, this was a radical question to ask, and he was placed in the vanguard of critics of modern medicine that had been spawned by the political and social revolts against authorities during the countercultural movement of the period. It was a mistaken placement: McKeown was not interested in tearing down, merely in understanding the historical role of medicine.

His later papers and books extended his analysis, both temporally and in the causative factors he invoked. As he examined the major infectious killers of the 19th century—tuberculosis, typhus, typhoid, scarlet fever, diphtheria, pneumonia, and the rest—his familiar trademark appeared. This was the recorded death rates from these individual diseases, invariably showing a steady decline, with places marked where specific therapies or preventives appeared. Most of the decline had always occurred before the specific measures came on the scene. Tuberculosis lost about 75% of its mortality from its known high before streptomycin was available. Scarlet fever and pneumonia did the same before the sulpha drugs and penicillin, diphtheria before antisera and inoculation. In each case, the contribution of specific modern medical interventions accounted for only a small part of the historical fall in the mortality of the major infectious diseases.

In the 1950s and early 1960s, this was pretty heady stuff. It seemed to fly against the many recent medical achievements, themselves built on gradually increasing clinical, preventive, and scientific knowledge. McKeown continued to modify his thesis, ironing out some of its starkness as he moved his analysis forward. He never budged on his conviction that medicine had contributed little to the western decline of mortality until well into the 20th century. Smallpox vaccination excepted, he even discounted a good deal of public-health activity before the 20th century, concluding that improved nutrition, the result of ameliorating standards of agriculture, was the major cause of mortality decline, and hence, population rise. In the bald version of his thesis, the modern demographic revolution was agricultural, not social or medical.

McKeown gathered exponents but also attracted critics. Historical demographers patiently counted births and deaths from local registers whenever the records permitted (the first census in the UK was 1801, civil registration of births and deaths 1837), and concluded that the initial population spurt in the 1760s was actually a fertility burst, based on decreasing average age of marriage. Clinicians quietly suggested that McKeown lacked much bedside experience and it told. His graphs took old diagnostic categories and lumped them into modern, unchanging ones. Historians began to examine more closely early public-health movements, and argued that medically motivated improvements in housing, water supply, isolation of the sick, and other measures had also contributed to the gradually lengthening life expectancies in the 19th century, made more impressive because of the mortality penalty attached to urbanisation. (Cities had always been unhealthy places, and the same death rate for a rural and an urban population was a positive achievement for the latter.)

Full-size image (96K) BMJ 1988; 297: 129

Thomas McKeown

Reproduced with permission from BMJ Publishing Group.

During his lifetime, McKeown became a mouthpiece for a position about the ineffectiveness of medicine before the 20th century. He was hardly the first to argue this scenario, but he sometimes went further, in discounting most human agency in the modern decline in mortality. His position, argued with little reference to research other than his own and only modestly modified in his later volumes, became more dogmatic the older he got. His only concession was to contemporary medical capability: our medicine can at last do some good (as well as ill).

Despite McKeown's sharp reading of the therapeutics of our forebears, he never argued that it was valueless. He always allowed an important historical caring role for medicine. Unlike many of the 1960s countercultural critics with whom he was sometime grouped, he was situated firmly within the medical establishment and its traditions. His great virtue was to ask the right questions. He did not always provide the best answers.

Further reading

McKeown and Brown, 1955 McKeown T, Brown RG. Medical evidence related to English population changes in the eighteenth century. Popul Stud 1955; 9: 119-141. PubMed

McKeown, 1976 McKeown T. The modern rise of population. London: Edward Arnold, 1976.

McKeown,1979 McKeown T. The role of medicine: dream, mirage or nemesis. Oxford: Blackwell, 1979.

Szreter, 1988 Szreter S. The importance of social intervention in Britain's mortality decline c. 1850—1914. Soc Hist Med 1988; 1:1-37. PubMed