Specificity is the unsung hero in general practice. When I was a medical student it was the poor relative to sensitivity. Sensitivity was all about making smart diagnoses. But as you get older you realise the importance of identifying those who should remain confident in their health—the importance of not seeing disease everywhere, of not medicalising the world.
When trying to explain the fundamental laws of nature the physicist Richard Feynman used the analogy of watching the gods playing chess. If we do not know the rules then we struggle to see what is going on. The gods play fast and loose, and we cannot discern the pattern in the complexities of the game. But then we notice a conserved rule. The bishop always stays on the same colour square. We may look away, our attention may be deflected by the rich diversity of the world, but when we look back at the game this feature is unchanged. We have seen a pattern—a conserved property.
Sometimes I feel as though, under the surface of medicine, there are some great rules that I am missing. Buried in the complexity of symptoms, biological age, organic disease, unhappiness, and anxiety, there are deep conserved principles that are not quite discernible. The principles may be “intuition” or a “clinical nose.” They guide our actions in a way that we would never be able to defend in a court of law. But the whole process is unsatisfactory because while it is powerful and real—it (usually) helps the experienced to make fewer mistakes than the inexperienced—it is poorly defined.
Yet no laboratory test ever comes close to intuition in this level of specificity and sensitivity. Almost everybody coming through the door could have significant disease on the basis of their symptoms but it is potentially immensely harmful if they are all investigated.
General practitioners should be utilitarians and should be encouraged to be so. It is possible never to miss a diagnosis but in the process to create huge anxiety in legions of people by over-investigating them. The old adage may be true—that if you never make mistakes then maybe you are not seeing enough patients. The arithmetical benefit of causing huge anxiety to the legions of worried well with low risk of significant disease but picking up the one phaeochromocytoma does not add up. Jeremy Bentham would turn in his grave.