Chapter 24: Cautionary methods: towards a safe diagnostic strategy

Introduction

The stories told in this book demand that general practitioners have an incisive detective-like approach to our discipline, which is arguably the most difficult, complex and challenging of the healing arts. Our field of endeavour is at the very front line of medicine, and as practitioners of first contact we shoulder the responsibility of the early diagnosis of very serious, perhaps life-threatening, illness in addition to the recognition of anxiety traits in our patients.

Over and over again the old medicine adage ‘More things are missed by not looking than by not knowing’ has been stressed. However, our area is characterised by a wide kaleidoscope of presenting problems, often foreign to the classic textbook presentation and sometimes embellished by a ‘shopping list’ of seemingly unconnected problems—the so-called undifferentiated illness syndrome. It is important, especially in a busy practice, to adopt a fail-safe strategy to analyse such presenting problems. Such an approach is even more important in a world of increasing medical litigation and specialisation.

To help bring order to the jungle of general practice problems the author has developed a simple model to facilitate diagnosis and reduce the margin of error.

The basic model

The use of the diagnostic model requires a disciplined approach to the problem with the medical practitioner having to quickly answer five self-posed questions. The questions, for a particular patient, are as shown below.

This approach, based on considerable experience, requires the learning of a predetermined plan, which naturally would vary in different parts of the world but would have a certain universal application in the so-called developed world.

Each of the above five questions will be expanded.

1. What is the probability diagnosis?

The probability diagnosis is based on the doctor’s perspective and experience regarding prevalence, incidence and the natural history of disease. The general practitioner acquires first-hand epidemiological knowledge about the patterns of illness (apparent in individuals and in the community) that enables him or her to view illness from a perspective that is not available to doctors in other disciplines. Thus, during the medical interview, the doctor is not only gathering information, allocating priorities and making hypotheses, but is also developing a probability diagnosis based on acquired epidemiological knowledge.

2. What serious disorder(s) must not be missed?

While epidemiological knowledge is a great asset to the general practitioner, it can be a disadvantage in that what is common is so familiar that the all-important rare cause of a presenting symptom may be overlooked. ...