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A comment diagnosis as a means of health forecasting
Soc. Sci. & Med., Vo[. 13A. pp. 165 to 167 Pergamon Press Ltd 1979. Printed in Great Britain
A COMMENT DIAGNOSIS
A S ~A M E A N S
OF
HEALTH
FORECASTING
KaRl POIKOLAINEN* Department of Public Health Science, University of Helsinki
Abstract--Medical diagnosis is seen as a means of predicting a patient's future health. Diagnosis is an abstract model of concrete morbid processes manifesting themselves as symptoms in living beings. The model is useful, if it facilitates the deduction of a patient's prognosis from abstract, general medical knowledge concerning disease processes.
An important prerequisite for the advance of science is awareness of the concepts used, a reflective attitude to these theoretical tools. Diagnosis is the pivotal concept of medicine. It has such a fundamental character that one hardly ever asks what it actually is. Fortunately, when controversy arises about whether or not a certain class of phenomena lies in the province of medicine, the clarification of diagnosis becomes an important task. Alcoholism is probably the most controversial and most widely discussed of such borderline categories. An interesting attempt has been recently made to increase understanding of this concept [1]. However, some of the viewpoints expounded therein seem to me to be open to further elaboration. I shall therefore try to present ideas about both alcoholism and diagnosis in the hope that this will further analysis.
DIAGNOSIS--A
cal advice, is that which often follows diagnosis. It is not, however the diagnosis itself. DISEASES ARE NOT LIVING BEINGS
MEANS OF PREDICTION
I n my opinion, diagnosis is essentially a means of prediction. It is a hypothesis about a patient's prognosis based on ideas about his or her diseases and their causes. It may perhaps be even more accurately regarded as a process which results in a forecast of the patient's future health. The process is initiated by symptoms. Symptoms are all those self-perceived, physical, radiological, biochemical or other findings which deviate from the normal. Normal may be defined as that which is beyond the usual ergodicity range of the living organism. In the first place, the patient and the physician alike both want to know what the symptoms mean in t e r m s of the quality of future life. If the prognosis is worse than normal, they then ask what may be done to remedy the situation. Historically, as ()berg has convincingly pointed out in his analysis of disease concepts, the symptoms chosen for diagnosis during different phases of the development of medicine have been those which, at the time, have been known to have the best prognostic value [2]. Diagnosis is therefore prediction rather than prescription. Prescription, the act of giving medi-
Disease and cause are ctosely related but conceptually different notions. This may seem self-evident but in practice these concepts arc commonly confused: this leads to the reification of disease, to the belief that diseases are independent living beings [3]. There are at least two causes for this conceptual confusion. First, diseases are often given names which are partly derived from their causes. For example, salmonellosis refers to an inflammation of the gut caused by bacilli belonging to the genus Salmonellae. In spite of the similarity in name, the disease is not the same as the bacilli. The latter may also be present in human organisms in instances when the host is asymptomatic. Only when symptoms indicating inflammation of the gut arise, may a morbid process, satmonellosis, be presumed to be going on in the host. Secondly, the names of pathognomonic findings for diseases have sometimes been given to their newly found etiological agents. Tuberculosis is a good example of this. The Mycobacteria found to associate with certain pathological structures called tubercles were named after this lesion [4]. However, microbes infecting the organism are only one type of causal agent in such disease cases. As there are symptomless agent carriers, it is easily understood that there are other classes of causal factors necessary for the production of disease, too. For the above ~reasons it would be misleading to argue that some of the classes in the International Statistical Classification of Diseases, Injuries, and Causes of Death (ICD) are "essentially assertions about the cause of disease" [1-l. Although some of the causal factors appear in the names of the diseases, it is the diseases that arc classified, not their causes. DISEASE AND DIAGNOSIS ARE ABSTRACTIONS
Symptoms are facts: diagnosis is an assumption [2]. Diagnosis is an abstract model of concrete mor• bid processes mamfestmg themselves as symptoms in real living organisms. A model of disease and their causes facilitates the deduction of a patient's prognosis from abstract, general medical knowledge concerning disease processes. It would seem improper, .
* Department of Public Health Science, University of Helsinki, Haartmaninkatu 3, SF-00290 Helsinki 29, Finland and Finnish Foundation for Alcohol Studies, Kalevankatu 12, SF-00100 Helsinki 10, Finland. 165
.
~q
166
A Comment
therefore, to regard disease categories as mere de[7, 8]. Therefore, it is at least premature to regard scriptions [1]. Admittedly, there are some categories alcoholism as a specific lesion~in the human organism. of symptoms in the ICD, but these are obviously While the speculation about alcoholism as a defect better understood as such, and not as disease cateis commonly held to have a basis in fact. the search gories. for the biological or psychological defect which might When thinking of diagnosis, it is useful to apprediscriminate between compulsive and normal drinkers ciate the reciprocal, feed-back nature of diagnosis and goes on. My expectations of the results of this line therapy. Diagnosis gives access to general medical of research are not optimistic. I would prefer to knowledge, from which prognoses and appropriate emphasize the value of studies concerning the effect therapy are deduced. The effects of therapy on the of sociological and behavioural factors on the varicourse of a disease may increase or decrease the crediation of alcohol consumption in populations and in bility of a diagnosis when compared with the probindividuals. Study of these factors would seem to take able natural course implied by prognosis. If the latter, us furthest in developing prevention and treatment the diagnosis should be reconsidered. Much of our of alcohol-related problems. general knowledge of health and disease has presumIn summary, alcoholism as a part of diagnosis may, ably developed through this kind of iterative thinking. in my opinion, be conceived of both as a functional, For this reason, the literal meaning of the word diag- poisonous disease and as a cause of the disease's nosis, "through the knowledge", seems to be so much . structural, organic complications. To regard alcoholto the point. ism as a manifestation of an enigmatic underlying defect would be ill-advised. Moreover, Blaxter's important findings, demonstrating that physicians who had WHAT IS ALCOHOLISM? adopted the latter view had a nonchalant attitude towards heavy drinking [1], seem to point out that Bearing the above in mind, what then is alcoholthis attitude may be an obstacle to good medical ism? Is it a diagnosis, a cause, a disease or a sympcounsel. tom? First, the use of alcohol may clearly be a cause of certain diseases. Second, the drinking of alcoholic beverages leads, with the exception of very small REFERENCES amounts over a very long period of time, to functional 1. Btaxter M. Diagnosis as category and process: the case disturbances, which may be called poisoning. It is of of alcoholism. Soc. Sci. Me& 12, 9, 1978. considerable interest that the term "alcoholism" ori2. Oberg L. Om r~itt diagnos ur historiskt och kSAlkritiskt ginally had this meaning. Magnus Huss (1807-1890), perspektiv (Correct diagnosis from the historical and the Swedish physician who is regarded as the inventor source-critical points of view). L~kartidningen 70, t648. of the term, apparently used it as a synonym for alco1973. 3. Eisenberg L. Delineation of clinical conditions: conhol poisoning [5]. Alcoholism may thus be regarded ceptual models of "physical" and "mental" disorders. as a poisonous disease with several possible organic In Research and Medical Practice: their Interaction. complications. Indeed, this conception seem to have Elsevier, Amsterdam, 1976. been the common view in the Scandinavian countries 4. Scadding J. G. Principles of definition in medicine with in the 19th and early 20th century [6]. Thirdly, the special reference to chronic bronchitis and emphysema. use of alcohol has often been considered to be a Lancet 1, 323, 1959. symptom of an underlying disease. As an unspecific 5. Huss M. Alcoholismus Chronicus eller Chronisk Alkosymptom, excessive use of alcohol is obviously in cerholsjukdom (Alcoholismus Chronicus or Chronic Alcotain cultures sometimes associated with many psyholic Disease), p. 191. Joh. Beckman, Stockholm, 1849. chiatric diseases. In addition, a distinct defect causing See also Poikolainen K. Alcohol Poisor,in9 Mortality in four Nordic Countries. Finnish Foundation for Alcoheavy alcohol use, and therefore use that appears to hol Studies, Vol. 28, p. 126. Forssa, 1977. be compulsive, has frequently been assumed to exist. 6. L~SfgrenB. Alkoholistv~rdens omfattning och organisaThis is nowadays widely believed to be the essence tion (The scope and organisation of care for alcohoof alcoholism. lics). Li~kartidningen 71, 2620, 1974. In spite of the widespread belief in the existence 7. Jetlinek E. M. The Disease Concept of Alcoholism, p. of an underlying defect that would explain compulsive 155. Hillhouse Press, Highland Park, N.J., 1960. drinking, there is no strong evidence for this assump8. Edwards G. The alcohol dependence syndrome: usefultion. The proponents of this line of thought usually ness of an idea. In Alcoholism--New Knowledge and admit the speculative character of their argument New Responses. Croom Helm, London, 1977.
A COMMENT DIAGNOSIS
A S ~A M E A N S
OF
HEALTH
FORECASTING
KaRl POIKOLAINEN* Department of Public Health Science, University of Helsinki
Abstract--Medical diagnosis is seen as a means of predicting a patient's future health. Diagnosis is an abstract model of concrete morbid processes manifesting themselves as symptoms in living beings. The model is useful, if it facilitates the deduction of a patient's prognosis from abstract, general medical knowledge concerning disease processes.
An important prerequisite for the advance of science is awareness of the concepts used, a reflective attitude to these theoretical tools. Diagnosis is the pivotal concept of medicine. It has such a fundamental character that one hardly ever asks what it actually is. Fortunately, when controversy arises about whether or not a certain class of phenomena lies in the province of medicine, the clarification of diagnosis becomes an important task. Alcoholism is probably the most controversial and most widely discussed of such borderline categories. An interesting attempt has been recently made to increase understanding of this concept [1]. However, some of the viewpoints expounded therein seem to me to be open to further elaboration. I shall therefore try to present ideas about both alcoholism and diagnosis in the hope that this will further analysis.
DIAGNOSIS--A
cal advice, is that which often follows diagnosis. It is not, however the diagnosis itself. DISEASES ARE NOT LIVING BEINGS
MEANS OF PREDICTION
I n my opinion, diagnosis is essentially a means of prediction. It is a hypothesis about a patient's prognosis based on ideas about his or her diseases and their causes. It may perhaps be even more accurately regarded as a process which results in a forecast of the patient's future health. The process is initiated by symptoms. Symptoms are all those self-perceived, physical, radiological, biochemical or other findings which deviate from the normal. Normal may be defined as that which is beyond the usual ergodicity range of the living organism. In the first place, the patient and the physician alike both want to know what the symptoms mean in t e r m s of the quality of future life. If the prognosis is worse than normal, they then ask what may be done to remedy the situation. Historically, as ()berg has convincingly pointed out in his analysis of disease concepts, the symptoms chosen for diagnosis during different phases of the development of medicine have been those which, at the time, have been known to have the best prognostic value [2]. Diagnosis is therefore prediction rather than prescription. Prescription, the act of giving medi-
Disease and cause are ctosely related but conceptually different notions. This may seem self-evident but in practice these concepts arc commonly confused: this leads to the reification of disease, to the belief that diseases are independent living beings [3]. There are at least two causes for this conceptual confusion. First, diseases are often given names which are partly derived from their causes. For example, salmonellosis refers to an inflammation of the gut caused by bacilli belonging to the genus Salmonellae. In spite of the similarity in name, the disease is not the same as the bacilli. The latter may also be present in human organisms in instances when the host is asymptomatic. Only when symptoms indicating inflammation of the gut arise, may a morbid process, satmonellosis, be presumed to be going on in the host. Secondly, the names of pathognomonic findings for diseases have sometimes been given to their newly found etiological agents. Tuberculosis is a good example of this. The Mycobacteria found to associate with certain pathological structures called tubercles were named after this lesion [4]. However, microbes infecting the organism are only one type of causal agent in such disease cases. As there are symptomless agent carriers, it is easily understood that there are other classes of causal factors necessary for the production of disease, too. For the above ~reasons it would be misleading to argue that some of the classes in the International Statistical Classification of Diseases, Injuries, and Causes of Death (ICD) are "essentially assertions about the cause of disease" [1-l. Although some of the causal factors appear in the names of the diseases, it is the diseases that arc classified, not their causes. DISEASE AND DIAGNOSIS ARE ABSTRACTIONS
Symptoms are facts: diagnosis is an assumption [2]. Diagnosis is an abstract model of concrete mor• bid processes mamfestmg themselves as symptoms in real living organisms. A model of disease and their causes facilitates the deduction of a patient's prognosis from abstract, general medical knowledge concerning disease processes. It would seem improper, .
* Department of Public Health Science, University of Helsinki, Haartmaninkatu 3, SF-00290 Helsinki 29, Finland and Finnish Foundation for Alcohol Studies, Kalevankatu 12, SF-00100 Helsinki 10, Finland. 165
.
~q
166
A Comment
therefore, to regard disease categories as mere de[7, 8]. Therefore, it is at least premature to regard scriptions [1]. Admittedly, there are some categories alcoholism as a specific lesion~in the human organism. of symptoms in the ICD, but these are obviously While the speculation about alcoholism as a defect better understood as such, and not as disease cateis commonly held to have a basis in fact. the search gories. for the biological or psychological defect which might When thinking of diagnosis, it is useful to apprediscriminate between compulsive and normal drinkers ciate the reciprocal, feed-back nature of diagnosis and goes on. My expectations of the results of this line therapy. Diagnosis gives access to general medical of research are not optimistic. I would prefer to knowledge, from which prognoses and appropriate emphasize the value of studies concerning the effect therapy are deduced. The effects of therapy on the of sociological and behavioural factors on the varicourse of a disease may increase or decrease the crediation of alcohol consumption in populations and in bility of a diagnosis when compared with the probindividuals. Study of these factors would seem to take able natural course implied by prognosis. If the latter, us furthest in developing prevention and treatment the diagnosis should be reconsidered. Much of our of alcohol-related problems. general knowledge of health and disease has presumIn summary, alcoholism as a part of diagnosis may, ably developed through this kind of iterative thinking. in my opinion, be conceived of both as a functional, For this reason, the literal meaning of the word diag- poisonous disease and as a cause of the disease's nosis, "through the knowledge", seems to be so much . structural, organic complications. To regard alcoholto the point. ism as a manifestation of an enigmatic underlying defect would be ill-advised. Moreover, Blaxter's important findings, demonstrating that physicians who had WHAT IS ALCOHOLISM? adopted the latter view had a nonchalant attitude towards heavy drinking [1], seem to point out that Bearing the above in mind, what then is alcoholthis attitude may be an obstacle to good medical ism? Is it a diagnosis, a cause, a disease or a sympcounsel. tom? First, the use of alcohol may clearly be a cause of certain diseases. Second, the drinking of alcoholic beverages leads, with the exception of very small REFERENCES amounts over a very long period of time, to functional 1. Btaxter M. Diagnosis as category and process: the case disturbances, which may be called poisoning. It is of of alcoholism. Soc. Sci. Me& 12, 9, 1978. considerable interest that the term "alcoholism" ori2. Oberg L. Om r~itt diagnos ur historiskt och kSAlkritiskt ginally had this meaning. Magnus Huss (1807-1890), perspektiv (Correct diagnosis from the historical and the Swedish physician who is regarded as the inventor source-critical points of view). L~kartidningen 70, t648. of the term, apparently used it as a synonym for alco1973. 3. Eisenberg L. Delineation of clinical conditions: conhol poisoning [5]. Alcoholism may thus be regarded ceptual models of "physical" and "mental" disorders. as a poisonous disease with several possible organic In Research and Medical Practice: their Interaction. complications. Indeed, this conception seem to have Elsevier, Amsterdam, 1976. been the common view in the Scandinavian countries 4. Scadding J. G. Principles of definition in medicine with in the 19th and early 20th century [6]. Thirdly, the special reference to chronic bronchitis and emphysema. use of alcohol has often been considered to be a Lancet 1, 323, 1959. symptom of an underlying disease. As an unspecific 5. Huss M. Alcoholismus Chronicus eller Chronisk Alkosymptom, excessive use of alcohol is obviously in cerholsjukdom (Alcoholismus Chronicus or Chronic Alcotain cultures sometimes associated with many psyholic Disease), p. 191. Joh. Beckman, Stockholm, 1849. chiatric diseases. In addition, a distinct defect causing See also Poikolainen K. Alcohol Poisor,in9 Mortality in four Nordic Countries. Finnish Foundation for Alcoheavy alcohol use, and therefore use that appears to hol Studies, Vol. 28, p. 126. Forssa, 1977. be compulsive, has frequently been assumed to exist. 6. L~SfgrenB. Alkoholistv~rdens omfattning och organisaThis is nowadays widely believed to be the essence tion (The scope and organisation of care for alcohoof alcoholism. lics). Li~kartidningen 71, 2620, 1974. In spite of the widespread belief in the existence 7. Jetlinek E. M. The Disease Concept of Alcoholism, p. of an underlying defect that would explain compulsive 155. Hillhouse Press, Highland Park, N.J., 1960. drinking, there is no strong evidence for this assump8. Edwards G. The alcohol dependence syndrome: usefultion. The proponents of this line of thought usually ness of an idea. In Alcoholism--New Knowledge and admit the speculative character of their argument New Responses. Croom Helm, London, 1977.