Most doctors will only treat problems that have already arisen.  Anything, from cancer to AIDs, all the way down to common allergies, are usually treated once they have become a problem which is serious enough to warrant medical attention.  Part of the reason for this is that doctors still require a thorough diagnosis before they can choose the best treatments for any given patient.  More often than not, a medical problem needs to become serious enough before a doctor can determine the best course of action. While this may seem to be a logical and inevitable part of the process, there is still another reason why preventative medicine is being held back.  The high cost of medical care in many countries has made it difficult for people to seek proper treatment.  In many cases, a person can only afford a certain treatment because their health insurance pays for the bulk of it.  If they were forced to pay out of pocket, as is true in some cases, the proper treatment would simply be out of their reach.  The problem is that it is often insurance companies, and not doctors or patients, who determine when someone receives treatment and what procedures they can have. Insurance companies will most often rely upon a doctor's diagnosis when deciding the fate of a patient.  A doctor needs to be able to prove that a person's quality of life will be greatly diminished if they don't receive the prescribed treatment.  In some cases, the doctor