J Clwon Dis Vol. 32. pp. 1 I5 to 116 Pergamon Press Ltd 1979. Printed in Great Britain
HIGHLIGHTS PAUL
OF CONFERENCE STOLLEY
IT IS usual to begin a summary of a large conference for the person who is given the onerous task of summarizing a wide ranging conference to claim that it is an impossible task. I want to let you know that it is not impossible. It is possible, but it is very dull and you would not want to hear it. So, my remarks will be very brief. I have an impulse to respond to the request to summarize this conference in a similar fashion as a high school student who, when asked to summarize Moby Dick, a book he had been reading all semester in his English literature class, replied, “Well, it’s a story about a whale,” which in his opinion was an entirely sufficient response. My task is to reduce the leviathan, that is this conference, to its cogent parts and I am not going to try to paraphrase all of the speakers. Rather, I will try to provide focus for our remaining hours together by pointing out those areas which require further discussion and possibly research; and state those areas where there appears to be a consensus. I believe there is general agreement that a set of standards or criteria for the conduct of case-control studies is worth developing, though it is clear it cannot be universally applied. However, it might serve as a very useful checklist for researchers. Certain issues of confounding and bias must be addressed and studied, even if merely to acknowledge that the bias could not be completely avoided or even measured. Various lists or catalogues of different types of bias were presented, but the relative importance and presence or absence of these types will vary from study to study. For me, a very rewarding aspect of this meeting was the constructive attitudes displayed by several critics of case-control studies. Not only were they willing to modify their former views, but they have joined those epidemiologists who have been conducting these studies in a search for new and improved methods to deal with confounding and bias. The scientific temper is one in which constant revision of views should be possible with a minimum of rancor. I think we must thank the moderator and planners of this symposium for creating the kind of atmosphere where an open but tolerant discussion could take place. Having agreed there is a place for case-control studies, there was much less agreement on certain technical points concerning their conduct and methods. Some were less important than others and my list of important and still unresolved points follows and may provide a useful guide for the discussion that will ensue. The matter of control selection No generally preferable strategy was endorsed although the pitfalls of selecting controls with a single disease or a disease induced by the agent under study was stressed. It is clear that more research is required concerning the biases inherent in the selection of different types of controls. It is possible that some of the methods advocated to deal with bias, e.g. disease detection bias, may in turn introduce other even more severe bias. Obtaining
histories
of exposure
The clinical pharmacologists stressed the difficulty of obtaining a reliable and valid drug history. Very little work has been carried out on this methodologic problem, but it is clearly central to many adverse reaction investigations.
116
Highlights of
Conference
The question of matching and post-stratification
This question of which is the preferable form of analysis provoked much discussion but little agreement and perhaps generalizations are not possible or desirable. The extent to which newer methods of multi-variate analysis have obviated matching on key attributes is still not entirely clear and requires further elaboration. Injluence upon public policy
Our discussion of to what extent public health policy should be influenced by casecontrol studies was the least satisfying of our forums, in my opinion. Perhaps the question is not really answerable, similar to the usual first effort of a novice researcher: too large a question and with too many variables under consideration. The view of Prof. Lilienfeld reminding us that the task of epidemiology includes the synthesis and integration of information from all fields of science and the need to bring all the available data to bear upon a decision I find both persuasive and pragmatic. The need for collatoration between clinical pharmacologists and epidemiologists was generally endorsed. but is seldom practiced. As one who has collaborated with my pharmacologic brethren in the past (and, if the gods of funds are kind, plan to do so again very soon) let me say that it can work and can only lead to better studies and improved understanding between the two disciplines. Finally, Dr. Buck spoke to us of our obligation to investigate possible environmental hazards such as chemical and industrial pollutants. Our methods are merely the tools we employ to help achieve our goal. A goal of which we must never loose sight, to prevent disease, devise better therapies, and to detect new health hazards as early as possible. The case-control study is only one way to help reach that goal and to the extent that it helps us come closer to that goal, we shall continue to employ it. Have we made progress these past few days’? Bertrand Russell has described scientific inquiry as the substitution of ever so tentative truths for cock-sure error. I think we have made a few tentative steps in this direction and suggest we pick a few topics where there is still considerable confusion upon which to concentrate our discussion for the brief remainder of the meeting.
HIGHLIGHTS PAUL
OF CONFERENCE STOLLEY
IT IS usual to begin a summary of a large conference for the person who is given the onerous task of summarizing a wide ranging conference to claim that it is an impossible task. I want to let you know that it is not impossible. It is possible, but it is very dull and you would not want to hear it. So, my remarks will be very brief. I have an impulse to respond to the request to summarize this conference in a similar fashion as a high school student who, when asked to summarize Moby Dick, a book he had been reading all semester in his English literature class, replied, “Well, it’s a story about a whale,” which in his opinion was an entirely sufficient response. My task is to reduce the leviathan, that is this conference, to its cogent parts and I am not going to try to paraphrase all of the speakers. Rather, I will try to provide focus for our remaining hours together by pointing out those areas which require further discussion and possibly research; and state those areas where there appears to be a consensus. I believe there is general agreement that a set of standards or criteria for the conduct of case-control studies is worth developing, though it is clear it cannot be universally applied. However, it might serve as a very useful checklist for researchers. Certain issues of confounding and bias must be addressed and studied, even if merely to acknowledge that the bias could not be completely avoided or even measured. Various lists or catalogues of different types of bias were presented, but the relative importance and presence or absence of these types will vary from study to study. For me, a very rewarding aspect of this meeting was the constructive attitudes displayed by several critics of case-control studies. Not only were they willing to modify their former views, but they have joined those epidemiologists who have been conducting these studies in a search for new and improved methods to deal with confounding and bias. The scientific temper is one in which constant revision of views should be possible with a minimum of rancor. I think we must thank the moderator and planners of this symposium for creating the kind of atmosphere where an open but tolerant discussion could take place. Having agreed there is a place for case-control studies, there was much less agreement on certain technical points concerning their conduct and methods. Some were less important than others and my list of important and still unresolved points follows and may provide a useful guide for the discussion that will ensue. The matter of control selection No generally preferable strategy was endorsed although the pitfalls of selecting controls with a single disease or a disease induced by the agent under study was stressed. It is clear that more research is required concerning the biases inherent in the selection of different types of controls. It is possible that some of the methods advocated to deal with bias, e.g. disease detection bias, may in turn introduce other even more severe bias. Obtaining
histories
of exposure
The clinical pharmacologists stressed the difficulty of obtaining a reliable and valid drug history. Very little work has been carried out on this methodologic problem, but it is clearly central to many adverse reaction investigations.
116
Highlights of
Conference
The question of matching and post-stratification
This question of which is the preferable form of analysis provoked much discussion but little agreement and perhaps generalizations are not possible or desirable. The extent to which newer methods of multi-variate analysis have obviated matching on key attributes is still not entirely clear and requires further elaboration. Injluence upon public policy
Our discussion of to what extent public health policy should be influenced by casecontrol studies was the least satisfying of our forums, in my opinion. Perhaps the question is not really answerable, similar to the usual first effort of a novice researcher: too large a question and with too many variables under consideration. The view of Prof. Lilienfeld reminding us that the task of epidemiology includes the synthesis and integration of information from all fields of science and the need to bring all the available data to bear upon a decision I find both persuasive and pragmatic. The need for collatoration between clinical pharmacologists and epidemiologists was generally endorsed. but is seldom practiced. As one who has collaborated with my pharmacologic brethren in the past (and, if the gods of funds are kind, plan to do so again very soon) let me say that it can work and can only lead to better studies and improved understanding between the two disciplines. Finally, Dr. Buck spoke to us of our obligation to investigate possible environmental hazards such as chemical and industrial pollutants. Our methods are merely the tools we employ to help achieve our goal. A goal of which we must never loose sight, to prevent disease, devise better therapies, and to detect new health hazards as early as possible. The case-control study is only one way to help reach that goal and to the extent that it helps us come closer to that goal, we shall continue to employ it. Have we made progress these past few days’? Bertrand Russell has described scientific inquiry as the substitution of ever so tentative truths for cock-sure error. I think we have made a few tentative steps in this direction and suggest we pick a few topics where there is still considerable confusion upon which to concentrate our discussion for the brief remainder of the meeting.
