So, how much can you rely on these fancy medical tests?
We have all heard about the fancy multi-million dollar MRI machines. You may also have heard about the state of the art medical DNA tests that can detect diseases long before the actual symptoms even appear. But do you really know how much you can rely upon these modern equipments to make the correct medical diagnosis?
When the test is normal, can you be sure that you do not have the disease? When the test is abnormal, can you be sure that you do have the disease?
Well, you may be disappointed to know that even the most sophisticated medical equipment is not perfect. In fact, most medical tests are far less accurate than you think they are. If you randomly order a test on ten normal people, you may have one of them falsely identified as having a positive test for the disease. On the other hand, if you take patients who are already diagnosed with that disease and run that diagnostic test on all of them, you may find out at least one of them will be falsely labeled as disease free based on the test result.
Let us look at the implications of the above discussion. If your MD doctor completely relied upon these tests to make the medical diagnosis, one out of ten patients will have a wrong medical diagnosis and one out of ten patients will have the medical diagnosis completely missed.
So, how does the MD doctor practice medicine in a world where the tests available to him are so imperfect? Well, it takes a MD doctor with an imperfect human brain to practice medicine when the tools available to him are less than perfect. The good MD doctor uses his judgment and wisdom instead of blindly following the test results. He will spend some time talking to the patient and their family to put everything in the right context. He will only order the tests to confirm or discard a medical diagnosis in the right setting so that the test results make more sense.
If you would like to understand why all these medical tests are so imperfect even in this day and age, you can read all about them in the book. Everything is written in plain English without any medical terms so that you can understand what you read without any prior medical knowledge.