The Value of Case Studies*
I.R. McWhinney, OC, M.D., FRCGP, FCFP, FRCP
Department of Family Medicine
The University of Western Ontario
London, Ontario Canada
Reproduced with Permission from European Journal of General Practice
* European Journal of General Practice 2001;7 (September):88-9. (Copyright) Mediselect, The Netherlands.
Case studies have played an important part in the annals of general practice Ė and indeed of clinical medicine. Jennerís discovery of vaccination culminated in the demonstration of its effectiveness in a boy called James Phipps (Fisk, 1959). Je nnerís case did not stand alone. His experiment came after years of meticulous observation of the skin infections of dairy workers, enabling him to make the crucial distinction between cowpox, which conferred immunity to smallpox, and other infections, wh ich did not. Thus, Jenner successfully integrated the concrete with the abstract, the particular with the general and lessons from individual cases with the theoretical principles derived from the collective.
Mackenzieís research on heart disease in his practice was similarly based on case studies of patients he knew well and followed for many years. In the course of his observations he was able to demonstrate in a single patient the onset of what he called paralysis of the auricles, known now as atrial fibrillation. In 1907 he wrote to a colleague: "take the case of Mrs. Still who gave me the first notion of auricular paralysis in 1897." (Mair, 1973). As with Jenner, the case was the culmination of years o f observation of patients with rheumatic heart disease and arrhythmia.
In her interviews with Scottish G.P.ís Reid (1982), noted that some doctors were unable to think of general practice in any other way than their individual patients. I believe it is true to say that G.P.ís tend to be concrete more than abstract thinker s. An actual case brings things alive for us in a way that aggregated data can not do. We learn differently from individual cases. They stimulate the imagination, open up possibilities, provoke us, and perhaps disturb us. They fill in the gaps left by pow erful generalizations, reminding us that every illness is unique in the same way. However, there are also pitfalls if we rely too much on the cases we remember. To reflect on our care of patients with diabetes or hypertension we need to look at the aggreg ated data, as well as individual cases who may illustrate a principle. The tendency to concrete thinking puts us at variance with academic medicine and we do best if we can reconcile our natural tendency with a capacity to think in general terms about our patients and our community.
Case studies, some of them book long, have made a notable contribution to scientific medicine, though nowadays often dismissed with that thoughtless term, "anecdotal." "We need," wrote Oliver Sacks, "in addition to conventional medicine, a medicine of a far profounder sort, based on the profoundest understanding of the organism and of the life." (Sacks, 1973). Empirical science is the key to one form of knowledge, the generalized knowledge that gives us power over nature; the key to wisdom however, is the knowledge of particulars.
With its tradition of bedside teaching, medicine has always retained its focus on the individual patient. In the modern era, the clinico-pathological conference has served as an educational tool and an illustration of a clinical method. Too often, howe ver, the patient does not leap from the page as an individual. The patientís family doctor is not usually present. On one occasion when he was present, there was an exchange between the GP and the professor of medicine, a clash of two world views that onl y an individual case could bring to life (McWhinney, 1997). We have yet to see case studies which will do for the patient-centred clinical method what the clinico-pathological conference has done for differential diagnosis.
A case study Ė perhaps of an unexpected bad outcome - may be the trigger for quality assurance. In this issue [the authors] present a case study to focus attention on weaknesses in a health care system. The absence of a gatekeeper role enabled the pati ent to reject the advice of his general practitioner and make his own referral to a specialist. When using case studies to draw attention to weaknesses in a system, we need to be sure that the case is not an isolated instance of failure, but a true repres entation of a malfunctioning system. If we are thinking with a system perspective, we should also be aware that the point where a system fails is often a weakness due to failure in other parts of the system. A system is defined as, "a dynamic order of par ts and processes standing in mutual interaction with each other." (Von Bertallanfy, 1968) It is necessary, therefore, to examine all the parts and processes, especially the interactions between parts. One of the common failures in health care systems is i n the interaction between the primary and secondary levels of care.
In [the authorís] case, a patientís non-compliance with his G.P.ís advice set in motion a series of events made possible by a system of open access to specialists. To us it seems intuitively obvious that effectiveness and efficiency are both enhanced w hen there is a gatekeeper role for the primary care physician. Others will object on the grounds that G.P.ís, like other physicians, make mistakes. In broad terms, our mistakes tend to be "false negatives, " whereas the errors of specialists tend to be "f alse positives." (Starfield, 1998). The justification for the gatekeeper role is that healthy patients are prevented from coming in significant numbers to specialists. Even with a well functioning system, some mistakes will be made in both directions. The best system will be one in which the benefits outweigh the risks and in which fail-safe mechanisms are in place to minimize risk. The public will be justified in questioning limitations on their freedom, in demanding evidence of effectiveness and reassur ance that our belief in gatekeeping is not self-serving. For patients, the freedom to change their family physician can provide some reassurance. There is already some good evidence in favour of gatekeeping (Starfield, 1998). However, as Starfield maintai ns, we do need more research on the need for referral and the role of free choice of primary care physician Ė from individual practices and from collaborative and system-wide studies.
Fisk D.Dr. Jenner of Berkeley. London: Wm. Heinemann,1959:page 129.
Mair A. Sir James Mackenzie 1953 Ė 1927, General Practitioner. Edinburgh:Churchill Livingstone, 1973: page146.
Reid M. Marginal Man: The identity dilemma of the academic general practitioner. Symbolic Interaction, 1982; 5:325-342.
McWhinney I. A Textbook of General Practice. New York:Oxford University Press, 1997:61-62.
Sacks O. Awakenings. London: Pan Books, 1973.
Starfield B. Primary Care: Balancing Health Needs, Services and Technology. New York: Oxford University Press, 1998.
Von Bertallanfy L. General System Theory. New York:George Braziller. 1968.