Coleman’s 2nd Law of Medicine: Tests are useless unless the Results will affect your Treatment

A few years ago I created 12 laws of medicine designed to help patients get the best out of doctors and hospitals.

Coleman’s Second Law of Medicine states that there is no point in having tests done unless the results will affect your treatment.

Now tests are, of course, often vital – essential to the making of an accurate diagnosis. But there are often risks attached when tests are done, and if tests are done which have no real value then there can be no upside – just the downside.

If your doctor wants you to have tests done ask him how the results will affect your treatment. If the results of the tests won’t affect the treatment you receive (and aren’t needed as a baseline against which to compare future tests) then the tests aren’t worth having.

Tests and investigations are often performed routinely, as a habit, and often performed in huge numbers. In private hospitals extra tests can result in huge profits for doctors, laboratories and the hospital.

Despite evidence to the contrary, tests are often regarded (by both doctors and patients) as being harmless. They aren’t.

There is no such thing as minor surgery (that’s Coleman’s 11th Law of Medicine) and even taking blood is an operation.

There are dangers inherent in every test that is performed. It used to be normal for all patients admitted to hospital to have routine chest X-rays – but this of course was extremely dangerous. X-rays can be carcinogenic and there is no doubt that routine X-rays have caused many cancers.

And there is, in addition, the danger that the result will be wrong and that your doctors will treat the test rather than treating you.

One of the problems with doctors doing too many tests and investigations is the fact that doctors often refuse to start treatment until they have received all the test results back. If they get test results within hours or days that is fine. But in some hospitals it can take months for test results to return.

Patients sometimes die untreated because doctors will not (or dare not) try treatments until all the investigations have been completed. The threat of litigation means that doctors insist on waiting for convincing evidence before trying anything. Inevitably, this means that it is not infrequently too late to act by the time treatment is started. If, for example, there are two or three possible diagnoses available and only one of the diseases can be treated then it would seem to me to make sense to start the treatment for the disease which can be treated, even though laboratory evidence in support of that diagnosis might not be available. But this isn’t what happens.

Doctors have a tendency to treat investigation results rather than patients. Don’t let them do this to you. When clinical observations and laboratory findings are incompatible, I think we should assume that the laboratory findings are wrong.

The important question to ask, when any test is being planned, is: will the results of this test affect my treatment?

If the answer is that the test won’t influence your treatment then what’s the point in doing the test? This brief summary of Coleman’s Second Law is adapted from Coleman’s Laws: The Twelve Medical Truths You Must Know to Survive by Vernon Coleman which is available on Amazon as a paperback and an eBook.