The Diagnostic Process and Multiple Screening Techniques

Abstract

Medical examination of the patient may be of two fundamental kinds. It may concern itself with his presenting complaint. It is then a matter of solving a problem by a method which is by nature sequential. It differs logically from classical sequential analysis in that pieces of information to be used as evidence are neither infinite in number nor mutually independent; moreover the process is complicated by considerations of »cost«, by the fact that multiple pieces of information may be solicited simultaneously, and in many cases by the real-time nature of the problem. Alternatively the examination may be directed to the problems of a population as a whole (such as is the case with epidemiological studies, preventive physical examinations and multiphasic screening) where the logical process is more akin to the classical methods for non-sequential analysis. It has not been sufficiently stressed that the clinical introduction of multichannel analysers (which furnish the physician engaged in the first kind of activity with masses of unsolicited information) carries with it the logical attributes of a population study. Two solutions to the consequent logical disruption are suggested: either that the clinician ignore unsolicited information so that the established methods of medicine may be preserved; or that, with respect to unsolicited information the physician assume the responsibilities of preventive medicine with a drastic reorientation of his notions of the normal and the abnormal. The latter course is preferable, but also more complicated. Failure to confront the decision can lead only to chaos.

Dental caries paradigms in diagnosis and diagnostic research

“…Where the physician is primarily oriented towards differential diagnosis and to a lesser extent to treatment planning, the reverse seems to apply to dentistry, where treatment planning considerations outweigh differential diagnostic issues. This illustrates the fundamental logical difference between the classical hypothetico-deductive differential diagnostic process invoked when examining a sick patient and the activities carried out in routine check-up examinations (67). Whereas the classical differential diagnostic process is oriented towards the solution of an existing problem, the routine dental screening examination is too cumbersome to be completed de novo for each single tooth surface in each single patient, and dentists therefore resort to rather different tactics (1), in the form of pattern recognition.…”

“…2), occasionally used to define high‐risk groups for caries (64), may circumvent the problem with the distributional assumption, both definitions have drawbacks because they imply a fixed frequency for any disease associated with the test parameter. It is also just a question of carrying out a sufficient number of independent tests before a person will be deemed sick (65–67). These distributional definitions are not widely used in caries‐diagnostic research, but can be encountered (68) and may gain increasing popularity as quantitative diagnostic methods continue to be developed.…”