Uses of Epidemiology
Uses of Epidemiology
Historical statements made in medicine are of two broad kinds. The first describes the decline of infections, for example, and of nutritional deficiencies, and the main trends are usually very obvious. The other raises problems about the possible increase of various disorders, which is quite another matter. The questions usually put ('Have disk syndromes become commoner?' for example) are bedevilled by uncertainty about diagnosis and nomenclature in the past, and the lack of quantitative estimates of frequency at any time: how many cases occurred annually per 1000 men, aged x, in the 1930s and in the early 1950s? In such problems as the frequency of psychoneuroses, historical questions, which are often asked, are hopeless of direct answer; but even in disorders like leukaemia, urinary cancer or cerebral tumour, sub-arachnoid haemorrhage, dissecting aneurysm and the collagen diseases, it is exceedingly difficult to estimate how much a recent apparent increase reflects a true increase of disease, and how much it is the product merely of better recognition and greater availability of diagnostic services, etc. Such questions are clearly important because the role of environmental factors in aetiology, and of recent social change which may be associated with the increase, arises. As a result of a great deal of work, the increase of duodenal ulcer, cancer of the bronchus and coronary heart disease must now be accepted as a working hypothesis and guide to environmental study.
Epidemiology may further be defined as the study of health and disease of populations in relation to their environment and ways of living. In a society that is changing as rapidly as our own, epidemiology has an important duty to observe contemporary social movements for their impact on the health of the population, and to try to assess where we are making progress and where falling backan activity in line with the classic descriptions of famine and pestilence, of the relations of health and disease to social dislocations, wars and crises. What are the public health implications of the 1000 extra motor vehicles a day?; the modern distribution of poverty so different from the 1930s?; the sophistication of foods?; the rising consumption of sugar, our astonishing taste for sweets?; the derationing of fats?; more smoking in women?; more married women going out to work?; less physical activity in work and more bodily sloth generally?; multiple chemical and physical exposures, know and potentially hazardous?; the prodigious increase of medical treatments?; the 11-plus examination?; still increasing urbanization and sub-urbanization?; the rapid creation of new towns?; smokeless zones (still with sulphur)?; the building of new power stations? and what can we learn from other indicators of community health: crime, for examplethe ups and downs of juvenile delinquency, and the apparent increase of sex crimes and of crimes of violence during a period when so much other crime is decreasing?
Some of these questions are being studied, some cannot yet be framed in scientific terms; but parts, at least, of some could be better tackled than they are. And there are even more fundamental problems in our society; perhaps epidemiology with its concern for woods rather than trees, its special ability to isolate major characteristics for study, can simplify the issues and usefully raise some bold questions about these, too. Indices of health are available, and their quality is improving, although many more are needed, particularly in 'mental health'.
For many the main interest of history is the light it can throw on the future. Vital statistics is better placed than most disciplines to forecastfor example, the whole population of old people of the second half of the century are already born and are leading their lives under the conditions we know. Figure 1 a can therefore be projected ahead, if only with wide margins of confidence. What seems to be keeping the male death rate even as moderately satisfactory as it is now is the balancing of those diseases, which are increasing (such as 'coronary thrombosis') by those which are declining (tuberculosis and other infections). If the infectious diseases begin to reach some minimum before the modern epidemics are brought under control, or if their decline is halted, and if the large group of conditions that are relatively static (cancer of the stomach, cerebrovascular disease, etc.) do not show improvements in the meantime, the overall middle-aged male death rate will actually begin to rise. One consequence of this would be that the population of old people in the future will consist more and more of solitary old women (whatever the increasing popularity of marriage during recent years). The current trend of mortality in middle-aged males is the most striking feature of Western vital statistics. Very interestinglyanother kind of epidemiological comparisonthe situation is better in Scandinavia than in the English-speaking world, as illustrated by figures like these:
Mortality Per 1000 aged 55-64 From All Causes. (Mean of Rates For Separate Countries. Latest Available Year)
Searching questions need to be asked in this kind of situation. A first 'reconnaissance' suggests that there is no simple answerall these populations, for example, have high living standards and nutritional levels.
Historical statements made in medicine are of two broad kinds. The first describes the decline of infections, for example, and of nutritional deficiencies, and the main trends are usually very obvious. The other raises problems about the possible increase of various disorders, which is quite another matter. The questions usually put ('Have disk syndromes become commoner?' for example) are bedevilled by uncertainty about diagnosis and nomenclature in the past, and the lack of quantitative estimates of frequency at any time: how many cases occurred annually per 1000 men, aged x, in the 1930s and in the early 1950s? In such problems as the frequency of psychoneuroses, historical questions, which are often asked, are hopeless of direct answer; but even in disorders like leukaemia, urinary cancer or cerebral tumour, sub-arachnoid haemorrhage, dissecting aneurysm and the collagen diseases, it is exceedingly difficult to estimate how much a recent apparent increase reflects a true increase of disease, and how much it is the product merely of better recognition and greater availability of diagnostic services, etc. Such questions are clearly important because the role of environmental factors in aetiology, and of recent social change which may be associated with the increase, arises. As a result of a great deal of work, the increase of duodenal ulcer, cancer of the bronchus and coronary heart disease must now be accepted as a working hypothesis and guide to environmental study.
Epidemiology may further be defined as the study of health and disease of populations in relation to their environment and ways of living. In a society that is changing as rapidly as our own, epidemiology has an important duty to observe contemporary social movements for their impact on the health of the population, and to try to assess where we are making progress and where falling backan activity in line with the classic descriptions of famine and pestilence, of the relations of health and disease to social dislocations, wars and crises. What are the public health implications of the 1000 extra motor vehicles a day?; the modern distribution of poverty so different from the 1930s?; the sophistication of foods?; the rising consumption of sugar, our astonishing taste for sweets?; the derationing of fats?; more smoking in women?; more married women going out to work?; less physical activity in work and more bodily sloth generally?; multiple chemical and physical exposures, know and potentially hazardous?; the prodigious increase of medical treatments?; the 11-plus examination?; still increasing urbanization and sub-urbanization?; the rapid creation of new towns?; smokeless zones (still with sulphur)?; the building of new power stations? and what can we learn from other indicators of community health: crime, for examplethe ups and downs of juvenile delinquency, and the apparent increase of sex crimes and of crimes of violence during a period when so much other crime is decreasing?
Some of these questions are being studied, some cannot yet be framed in scientific terms; but parts, at least, of some could be better tackled than they are. And there are even more fundamental problems in our society; perhaps epidemiology with its concern for woods rather than trees, its special ability to isolate major characteristics for study, can simplify the issues and usefully raise some bold questions about these, too. Indices of health are available, and their quality is improving, although many more are needed, particularly in 'mental health'.
For many the main interest of history is the light it can throw on the future. Vital statistics is better placed than most disciplines to forecastfor example, the whole population of old people of the second half of the century are already born and are leading their lives under the conditions we know. Figure 1 a can therefore be projected ahead, if only with wide margins of confidence. What seems to be keeping the male death rate even as moderately satisfactory as it is now is the balancing of those diseases, which are increasing (such as 'coronary thrombosis') by those which are declining (tuberculosis and other infections). If the infectious diseases begin to reach some minimum before the modern epidemics are brought under control, or if their decline is halted, and if the large group of conditions that are relatively static (cancer of the stomach, cerebrovascular disease, etc.) do not show improvements in the meantime, the overall middle-aged male death rate will actually begin to rise. One consequence of this would be that the population of old people in the future will consist more and more of solitary old women (whatever the increasing popularity of marriage during recent years). The current trend of mortality in middle-aged males is the most striking feature of Western vital statistics. Very interestinglyanother kind of epidemiological comparisonthe situation is better in Scandinavia than in the English-speaking world, as illustrated by figures like these:
| Males | Females | |
|---|---|---|
| Scotland, England and Wales, Canada, USA, New Zealand and Australia | 22.3 | 12.9 |
| Norway, Sweden and Denmark | 13.9 | 10.5 |
Searching questions need to be asked in this kind of situation. A first 'reconnaissance' suggests that there is no simple answerall these populations, for example, have high living standards and nutritional levels.
