Interpretation: Ways of Thinking about the Sciences and the Arts

10. Interpretive Practices in Medicine

∞∑∫ ∞≠ Interpretive Practices in Medicine Kenneth F. Schaffner University of Pittsburgh This article develops some examples of interpretation in medical practice . I begin with medical data, but need to first provide some definitions to pave the way for more explicit development. Some of these defined terms have nontechnical meanings, but for our purposes they need to be clarified further. Examples will include manifestations (symptoms, signs, and laboratory results) as well as ‘‘disease.’’ I then explore the problem of noticing and interpreting a manifestation as ‘‘abnormal.’’ This will raise valuational issues for the interpretation, as well as allow us to briefly survey several approaches to the notion of disease in medicine. From here,Iwillbegintoconsiderinferencetoanexplanationofthemanifestation —another form of interpretation. I will look at this explanatory issue both in the context involving a new disease, and then in more depth as involving a previously recognized disease. I will situate the characterization of an existing disease within a still additional aspect of interpretation—one that is an abductive and quasi-inductive logical reconstruction of the diagnostic process by using the example of the internist-∞ artificial intelligence in medicine diagnostic program. Some Examples of Interpretation in Medical Practice Medicine can be characterized in a number of different ways and from a variety of perspectives, but one way to begin is with data—more specifically the data presenting to the doctor or health professional Interpretive Practices in Medicine ∞∑Ω when a patient comes in for (what is perceived to be) a health problem. We will generically refer to these data as ‘‘manifestations’’; they include symptoms, signs, and laboratory information. Each potentially represents the manifestation of a disease or a medical condition. A key step, however, is identifying a manifestation as abnormal or unwanted, and as something that falls into the medical area as opposed to a manifestation of concern to the patient, or one that is medically not directly relevant —economic poverty, for example. The next key step, assuming the manifestation has been verified and is not a false positive, is to proceed to attempt to interpret the manifestation as the consequence of or associated with a disease. This is the process of constructing a diagnosis —typically what physicians call a ‘‘differential diagnosis.’’ The notion of a manifestation needs to be defined somewhat more precisely. As noted, typically manifestations include symptoms, signs, and laboratory results, but each of these subsenses can be characterized further. A symptom (medicine) is any sensation or change in bodily (or mental) function that is experienced by a patient (thus subjective ) and is associated with a particular disease (wordnet.princeton .edu/perl/webwn): for example, sharp pain. In contrast, a sign is any objective evidence of disease. Gross blood in the sputum is a sign of disease. It can be recognized by the patient, doctor, nurse, or others (www.medterms.com). Finally, what we mean by a laboratory result is data obtained by more technical processes, typically involving an instrument (s): examples are blood glucose measurements, X-ray pictures , genetic tests, and so on. A manifestation can be medically ‘‘normal ’’—though initially it may not be recognized as such—since it may be an outlier. Or it can be ‘‘abnormal,’’ and possibly associated with a cause, which may indicate the presence of a disease, or a prodrome (early stage) of the disease. The classification of a manifestation as abnormal can be facilitated by statistical analysis, but typically that identification involves, in addition, a value judgment that the manifestation can be associated with harm (to the patient or others—for example, a carrier), and that the harm is of the type (possibly) related to physical or mental ‘‘health.’’ To tackle this topic in any detail would take a book-length treatment , and some of those books will be cited below. But in spite of the extensive discussions in the philosophy of medicine literature on this topic, we still lack a clear consensus. For the purposes of this article, then, it will suffice to outline the two major approaches to these no- ∞∏≠ Kenneth F. Schaffner tions of health and disease. Those two major approaches are the valuefree notion of health and disease and the value-laden notion of health and disease. The Concept of Disease Exactly what a disease is, including the question of diseases’ ‘‘true existence,’’ has been a question that has occupied physicians, philosophers , and medical historians for centuries (see Caplan...