Disease Prevention From a Doctors' Perspective

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Medical Author: Dennis Lee, MD
Medical Editor: Melissa Conrad Stoppler, MD

Introduction - A Doctor's philosophy concerning disease prevention

Preventing disease is different from treating diseases. In treating diseases, doctors and patients are often willing to accept a finite degree of risk of side effects in order to achieve a cure or reduction of uncomfortable symptoms. In preventing diseases, doctors are extremely risk adverse. Remember, the first priority in doctoring is to "do no harm". Thus, when prescribing an agent for prolonged periods of time to prevent a disease that may or may not occur, the doctor would not want that agent to cause adverse side effects in a healthy person.

• Example: NSAIDs (nonsteroidal antiinflammatory drugs, a class of medications used for arthritis and other inflammatory conditions) have been known to inhibit the growth of colon polyps. Colon polyps are precursors to colon cancer. Why aren't doctors recommending NSAIDs to prevent colon cancer? Because prolonged NSAID use can have unwanted side effects such as ulcers, intestinal bleeding, and aggravation of liver and kidney diseases. Without prospective randomized placebo-controlled trials involving a large number of patients, doctors will not recommend NSAIDs for colon polyp and cancer prevention except in very special and limited situations.

Sometimes doctors are willing to recommend a long-term prevention treatment in the absence of any conclusive proof of benefit provided the treatment is safe. This is especially true if the rationale for the treatment also has a sound scientific basis and the treatment has been found to be beneficial in observational studies.

• For example: observational studies have shown that people who take folic acid supplements have lower blood levels of homocysteine. Observational studies have also shown that higher blood levels of homocysteine increase the risk of coronary arterioscleroses and heart attacks. Scientific studies have also shown that homocysteine can cause injury to the inner lining of arteries, thus promoting atherosclerosis. Even though there is not yet conclusive proof from prospective placebo-controlled trials that taking folic acid actually prevents heart attacks, doctors are recommending that all adults take a daily multivitamin that contains folic acid because it is known to be safe when taken over a long term.

In this situation, doctors do not want to miss an opportunity to recommend something safe to possibly prevent heart attacks while waiting for absolute proof of its effectiveness, which can be many years away.

• Another example: Blood cholesterol. Thirty years ago, observational studies suggested that high blood cholesterol (like homocysteine) could cause coronary artery disease and heart attacks. Even though there were no double-blind placebo-controlled trials available, doctors in those days suspected (correctly) that lowering blood cholesterol could reduce heart attacks. They were recommending low fat diets and exercise to lower blood cholesterol, and medications such as statins only when diet and exercise failed. They also did one very important thing-they started numerous, large-scale, randomized, placebo-controlled trials to determine if lowering cholesterol actually prevents heart attacks.

Today the prospective trials they started have been completed. These trials have conclusively shown that lowering cholesterol (especially the "bad" LDL cholesterol) reduces heart attack risks and prolongs life. These trials further showed that the benefits of lowering cholesterol outweigh the risks of side effects of the statin medications. Therefore doctors today are much more aggressive than doctors of yester-years when prescribing measures to lower LDL cholesterol. Doctors are much more willing to use medications such as statins to lower cholesterol, and the "normal cholesterol level" has been rapidly reduced.