Training for Uncertainty — Medical Education and
Socioeconomic Influences on Health

An inaugural lecture from the Chair of Community Medicine at The Chinese University of Hong Kong
delivered on 19th November 1982 by Professor SPB Donnan

The lecture as delivered was profusely illustrated with photographs, graphics and text slides.

Components of "community medicine"

• epidemiology
  
  
  
  
  

• public health
  
  
  
• primary care
  
  

Training for Uncertainty - Medical Education and Socioeconomic Influences on Health



I am pleased to have the opportunity to introduce to you and to The Chinese University of Hong Kong some aspects of the discipline of Community Medicine and of my own interests, Before I pursue the topics suggested (or perhaps concealed) by the title I have given to this Inaugural Lecture, I should begin with some definitions.

Community Medicine is a broad and mixed field, and this is made more complicated by two facts — first, over the ages different words have been used to describe the same problems or subject areas; and secondly, today the same words (Community Medicine) are used to describe very different aspects of medicine in different countries. In a few moments I will pursue the origins of the discipline but first let me define Community Medicine in The Chinese University of Hong Kong in 1982.

I recently received a note addressed to "Professor Dominant, Department of Commuting Management". People even in this University have trouble both with my name and with the name of the Department! But to define Community Medicine properly there are three components: first, 'Epidemiology' (which can he taken to include statistics and social sciences in medicine). The word epidemiology obviously has its origin in the word epidemic — a disease spread throughout a community or group of people. In the past the major epidemics were of course infectious, communicable diseases and this still applies in many countries today. As the relative importance of communicable diseases has decreased, the word epidemiology has come to mean 'the study of the health status of groups of people and of the factors which influence their health'. This is very comprehensive, hut there is at least one thing which being an epidemiologist does not mean — I am not a skin doctor!

The second component of Community Medicine in The Chinese University is 'Public Health'. This is an ancient and broad field, and involves the health of both individuals and groups. It also involves the work of both individual doctors and groups of doctors i.e. the organization of health services. The third component — which makes The Chinese University similar to many departments in the USA and Australia but different from Britain and also rather different from the University of Hong Kong is 'Primary Medical Care', often called General Practice. In The Chinese University we are or will he involved in the delivery of medical care — which is jargon for seeing and treating patients — as well as studying and endeavouring to influence the health of groups of people.

I wish now to turn to the English title of this lecture — taken from Renée Fox, who was part of Robert Merton's team of social scientists who published some of the first studies of the sociology of medical education in 1957. She discussed three aspects of uncertainty to which I wish to add two. So I will now ask you to consider with me five aspects of uncertainty for us as medical students and teachers and as medical consumers in Hong Kong.

First, uncertainty for medical students and for doctors and society as a whole arises from limitations in current medical knowledge about the nature and causes of diseases and other health problems. This leads me to a consideration of some of the history of medicine especially as it relates to public health or social medicine or community medicine.

The writings of Huang Ti, the famed Yellow Emperor, come from the first century or two BC. His treatise, The Yellow Emperor's Classic of Internal Medicine, contains a philosophy of living correctly and of maintaining health - hence the importance of prevention. As in the West, there was concern to minimize uncertainty: "The most important requirement of the act of healing is that no mistakes or neglect occur. There should be no doubt or confusion." I will now move ahead more than a millennium to mention some of the great men in the development of modern epidemiology - and return to the ancients later.

In the seventeenth century Bernardino Ramazzini became the father of one aspect of community medicine, namely occupational health, He took a broad view of causation of disease and said, "It is hardly ever possible to give any remedies that would completely restore health - for they suffer from yet another drawback - I mean they are very poor." He was writing of the working classes in seventeenth century Europe, but it was not only the poor who suffered from preventable diseases.

I have no time today to consider alcohol-related diseases - but there is a pub in soho in London called The John Snow, one of a very few named after doctors. (One of the others is named after W.G. Grace who may be more familiar to some people!) John Snow was a doctor in London in the mid-nineteenth century - he was a man of many parts and popularized chloroform as a general anaesthetic, and helped legitimize anaesthesia during childbirth by giving chloroform to Queen Victoria at the birth of Prince Leopold.

Epidemiologists revere John Snow because of the Broad Street pump and the surrounding events. The pub is located in what is now Broadwick Street. Snow's map of Soho in the mid-nineteenth century shows the sweep of Regent Street and where Oxford Circus and Piccadilly Circus now stand, with numerous black spots representing deaths from cholera in one of the epidemics in the 1850s. In Broad Street there was a water pump and Snow suspected - although nothing was known about bacteria then - that the water was somehow involved. Two factors were especially important in having the decision made to remove the handle of the pump. First, a brewery stood nearby but there were no cholera deaths among the workers - it was said that they never drank water! The second factor was an isolated death from cholera in Hampstead; Snow discovered that the good lady used to live in Soho, and liked the flavour of the water from the Broad Street pump - so her son who worked nearby would bring her a bottle of the water back to Hampstead each day.

Around the same time it was noted that deaths from cholera in South London varied from place to place, Snow proposed what he called 'an experiment on the grandest scale' and walked from house to house in Southwark and Lambeth testing which water company supplied the water to adjacent houses. There was overlap in some streets as Snow's own map showed. He was able to rest for different mineral content - not of course for bacterial contamination. The Southwark water company took its water from the Thames near London Bridge. The Lambeth water company had moved its source up stream to near Twickenham and piped the water down. Table I shows the results of the grand experiment, indicating that water supply rather than location was a likely culprit.



This table was published by William Farr who was the first medical statistician at the General Register Office in London and a colleague of snow. He was a physician with a broad view and used his position to investigate with considerable ingenuity and originality the facts of life and death in Britain.

You will remember that these investigations of cholera pre-dated the discovery of bacteria, but not by much. The name of Pasteur is well-known to all, but the name of Robert Koch probably only to the medical people present. He was the father of modern pathology and is famous an his war on Tuberculosis - in relation to which he published his famous 'postulates' concerning the relationship of organisms and diseases:

Koch's Postulates (c. 1870)

1. A specific organism must invariably be associated with all cases of the disease.
2. The organism must be isolated in pure culture and then subcultured over repeated generations.
3. When inoculated into a healthy susceptible animal, the organism must again cause the disease.
4. The organism must again be isolated in pure culture from the lesions of the disease.

It is unfortunate that this work was essentially a laboratory exercise; although for laboratory pathology it is vital, it omits aspects of disease in the real world of individual people and social groups. ln particular, postulate (c) applies in selected laboratory animals but not in humans - I shall return to this in a moment.

John Ryle is something of a hero of mine - he was a physician at Guy's Hospital and the Ryle's nasogastric tube is named after him. He became Professor of Medicine at Cambridge and in the early 1940s moved to Oxford to become the first Professor of Social Medicine - much the same as what we mean by Community Medicine. One of his best known books is called Changing Disciplines. His interests broadened from individual pathology to what he called 'social pathology' - which was not psychological medicine but concerned the relation of social and economic factors to the health of individuals and groups. In a much less exalted way I myself have followed Ryle's example of changing disciplines - it is about ten years since I left the Department of Surgery at Guy's.

ln 1942 Ryle wrote, "Various startling discoveries such as microbes and vitamins have brought about a tendency to neglect concomitant or primary causes, so that knowledge of the aetiology of disease has actually suffered from the very discoveries which should have enriched it." Robert Koch was infected with the tubercle bacillus but did not develop the disease in the way his laboratory animals did - he died from a stroke at nearly seventy years of age and illustrated that there was much more to TB than the bacillus.

If we now consider health, as indicated by deaths, in Britain, McKeown has shown that the death rate dropped dramatically following the agricultural revolution and the industrial revolution despite pollution, crowding and so on. Food and its distribution were vital. For TB in Britain the death rate dropped by about one-half between the time when death registration began (1838) and the time when the tubercle bacillus was described (about 1880) and by another three-quarters before any specific preventive or therapeutic measures were available (in the 1940s). This applied not only to Britain but to many Western cities. In Hong Kong the toll of tuberculosis has likewise fallen although, as with newer and developing countries, the means of prevention and treatment have been available at the right time.

It is said that smallpox inoculation was known in China at about 1000 AD and also that poor quality rice was known at that time to be associated with beri-beri. This is one of the so-called vitamin deficiency diseases which, as Ryle pointed out, results not primarily from a deficiency of one of the B Vitamins but primarily from a deficient diet and inadequate food production and distribution. lt is also said that in the thirteenth century AD Peking had the best drainage system in the world, and that at that time even the common people when travelling took care to drink only boiled water!

I would like to return to some of Farr's ideas. He investigated geographical variations in deaths and introduced the idea of age-specific death rates which are vital for comparisons if the populations of the different areas are made up of a different mixture of the various ages - obviously older people have higher death rates, He calculated 'expected' deaths for different areas. He also looked at variations in deaths related to food supplies. In London in the years of the mid-eighteenth century there was a very high correlation between the price of wheat and the number of burials - the more expensive the wheat, the greater the number of deaths. Farr's ideas are still used in Britain and in Hong Kong today and the same sorts of problems are found. Deaths from Bronchitis in England and Wales in 1970-72 were greater in the north than in the south but in every region unskilled workers (social class V) had higher rates than professional workers (social class I) with a gradient for the other occupational classes. Accidents in men showed a similar gradient, while in the children of men from the different occupational classes the same phenomenon existed for accidents, pneumonia and many other diseases.

Large numbers of numbers are bread and butter for the epidemiologist, Table II shows death rates at various age groups at various time periods for cancer of the cervix in women in England and Wales.

Uncertainty 1:
   Do we know?
   (Is it known?)

I would like to point out the meaning of the diagonals which are marked. You will understand that women in the next five year age group in the next five year period are more or less the same women - what we call an approximate birth cohort. The diagonals show the approximate year of birth. Figure 1 shows one line for the experience of each birth cohort of women.



You can see that the trend of a decrease at all ages is interrupted by an increase in the 1921 cohort - this is also apparent in the 1940-50 cohorts. The 1921-26 cohorts were sexually active during the 1939-45 World War and a close correlation has been shown between gonorrhea rates around the age of twenty and subsequent cervical cancer rates in these women. This is one simple example of an epidemiological input into the causation of diseases.

To take Hong Kong today, Table III shows that the crude (overall) death rate has not changed in fifteen years although in each age group the rate has fallen.


Because the population has been getting older, the crude rate is a poor summary of the situation and thus an age-standardized rate is used - here based on England and Wales, showing the decrease in average death rate if comparisons are made with the same population. With my colleagues, I have calculated age-standardized ratios for various diseases for various parts of Hong Kong. Respiratory TB, which I have already mentioned, has been a problem (Table IV) especially, for example, in Sai Kung (this might be related to the TB hospital - we are looking into this but do not think that is the full explanation).


Although there is an overall decrease, some areas still have a greater problem than others - the reasons may include those which I have already suggested. Ischaemic or coronary heart disease (Table V) also shows variations by area.


Work-related problems are also common in Hong Kong, and colleagues are investigating ways of monitoring the problem - although, for example, decompression sickness might be no problem if no tunnels were being built. The question of monitoring brings up a final aspect of uncertainty about diseases and causes. It is more true than most doctors are willing to admit that the presence or absence of any disease is often a matter of subjective rather than objective assessment. For example a group of expert cardiologists gave figures varying from 5% to 60% when asked whether abnormalities were present in ECG tracings! This is not to criticize - it is difficult, and opinions differ - but to point out that diagnostic criteria must be agreed and made as objective as is possible.

To conclude the first and longest section of my consideration of uncertainty may I quote from René Sand, a contemporary Belgian professor of Social Medicine, who has written on what he calls 'the Advance to Social Medicine'. "How was it that Hippocrates, the father of Western medicine, and those who came after him could observe the effects of poor nutrition, insanitary housing, and dangerous work without linking up these factors and their obvious sources i.e. poverty and occupation? The reason is that both theory and practice of medicine were much more concerned with prognosis and treatment than with research into causes ... it could not but be so ... the patient and the family wanted information about the length and probable issue of the illness and about cure or alleviation."

In China the philosophy was different and I will return to that at the end.

Uncertainty 1:
   Do we know?
   (Is it known?)

Uncertainty 2:
   Do I know?
   (Have I not learnt it
     or forgotten?)

The second aspect of uncertainty comes from incomplete or imperfect mastery of current medical knowledge. This sort of uncertainty is familiar to all of us who are or have ever been medical students, but of course it also applies to any student or ex-student. In medicine it is a problem because patients, and even some medical educators, often expect medical graduates to know everything.

In Hong Kong this is a special problem where patients often refer themselves to private specialists or subspecialists who may in fact be quite the wrong person to deal with the real problem because the patient's self-diagnosis has been incorrect and the wrong specialist has been consulted. On the other hand it is said that many General Practitioners in Hong Kong are reluctant to refer patients (perhaps for financial reasons) and thus the GPs act as though they were in fact fully competent in all specialties. Our objective, rather, is that future GPs in Hong Kong should be experts in distinguishing what can be managed by themselves and what needs referral to a specialist; and experts in comprehensive management of problems which need skilled care outside of hospital.

A colleague and I have recently asked medical students in Hong Kong about their attitudes to medical practice and medical education and I have been able to make comparisons with British medical students. These graphs show the percentage of students who agreed with the various statements: Hong Kong students are crosses and British students are zeros in different years of the course. S means Staff of my sample of British medical schools. We have not yet obtained the attitudes of Hong Kong teachers, and it will be obvious that the medical students in Hong Kong do not all come from The Chinese University.

First, (Figure 2) we asked whether students thought a doctor should not reveal uncertainty or ignorance to his or her patients. Students decrease in agreement as the course progresses - they are less concerned about ignorance, but the Chinese students are more concerned than the British.



Then we asked (Figure 3) whether the students thought that patients would lose respect for a doctor who admitted not knowing what the diagnosis was. Of course this ignorance, as in the previous case, could relate to the state of the art as well as individual ignorance; but the responses indicate an important cultural difference and perhaps account for the previous attitude. The British students are less concerned than before but the Chinese students just as much or more. We also asked (Figure 4) whether students found it difficult to behave confidently on the basis of inadequate evidence. All groups agree but the Chinese rather more than the British.



I suggest that teachers need to communicate truthfulness and realism to their students. But I also suggest that if patients and the general public were better educated about health and disease, pressures on doctors to assume the role of sage or even of success-guaranteed entrepreneur would be much lessened.