More cholesterol testing=more drug therapy who benefits?


I have 80-year-old patients who are worried about their cholesterol--they look skeptical when I advise against testing." This lament from one of our subscribers, a primary care physician, typifies the consequences of selling the public on the idea that a high blood level of cholesterol is bad before there is any evidence to show that lowering it will extend your life.

Cholesterol testing, once reserved . for people with heart disease, is now widely applied to everyone, regardless of age, gender, symptoms, or risk factors. This is largely the result of a nationwide government-sponsored campaign to "know your numbers," begun in 1987. The first target was the nation's doctors, the majority of whom were not convinced about the dangers of high cholesterol.

Yet such blanket testing invariably increases inappropriate drug use and exposes many people to risky drugs which can offer them no benefit. People with high cholesterol are put on a low-fat diet which usually produces only a minimal reduction; many wind up on lifelong medication. There has been a ten-fold increase in the prescription of cholesterol-lowering drugs in the last decade.

Cholesterol reduction clearly benefits people with established heart disease, but doubts linger over its value to healthy men and women with high cholesterol and no other risk factors for developing heart disease. Virtually all the intervention studies have been done on white middle-aged men with very high cholesterol. Little is known about the benefits of lowering cholesterol in everyone else.

A look at the testing recommendations from the various medical advisory groups is revealing. Their widely differing guidelines show that experts disagree about the safety and efficacy of encouraging widespread testing. Keep in mind that all are drawing from the same scientific evidence:

- The Canadian Task Force on the Periodic Health Examination concluded that there is insufficient evidence to recommend routine cholesterol screening but endorsed testing selectively in men 30-59 years old;

- The U.S. National Cholesterol Education Program recommends routine cholesterol testing of all adults age 20 and older at least once every five years;

- The American College of Obstetricians and Gynecologists recommends periodic screening of all women over age 20 and in selected high-risk adolescents.

The Canadian Task Force recommendations are the most accurate reflection of the scientific evidence, according to the summary of all relevant research in the 1996 Guide to Clinical Preventive Services by the U.S. Preventive Services Task Force. (Oddly, the U.S. Task Force's own guidelines are broader than the summary. indicates.)

A high blood level of cholesterol is only a risk factor, which means that population studies show that people with this test result have a higher probability of developing heart disease. But it doesn't always follow that lowering cholesterol improves your odds of living longer. In fact, more than 20 studies failed to demonstrate that cholesterol reduction had any effect on mortality.

Some of these studies did show a lower rate of cardiovascular death in the diet/drug-treated men, but this was offset by a high rate of death from other causes. For reasons that are not entirely clear, men whose cholesterol was reduced had higher death rates due to colon cancer, stroke, trauma, homicide, and suicide. (See HealthFacts, September 1992.)

The U.S. Preventive Services Task Force summarized ten meta-analyses of all relevant randomized trials published through 1993. When the Task Force singled out the trials that included only symptomless people, it found that neither the heart disease death rate nor the total death rate was significantly reduced by cholesterol reduction. Worse, non-cardiac mortality was increased 20-24% among men treated with cholesterol-lowering drugs. Overall, evidence is strongest for lowering cholesterol in symptom-less middle-aged men (ages 35-65) with very high cholesterol (mean 280 mg/dL). Their benefit was limited to a reduction in non fatal heart attacks.

A call was made to the Task Force for clarification. After reading the research summary, it wasn't clear why even screening all middle-aged men makes any sense. Dr: David Atkins, science advisor to the Task Force, acknowledged that until the newer drugs called "statins," such as lovastatin (brand name: Mevacor), came on the market, "Screening low-risk healthy men may not [have been] all that worthwhile because the benefit is too small in relation to the potential adverse effects of the drugs." (A example of a low-risk healthy man is a 40-year-old with high cholesterol but doesn't smoke or have hypertension.)

But until a few months ago all the published intervention studies involved older drugs (e.g., Lopid), Dr. Atkins explained in a telephone interview. Since the Task Force completed its guide, a new study was published which Dr. Atkins says justifies the recommendation of screening healthy middle-aged men.

A placebo-controlled study of over 6,000 Scottish men showed for the first time that healthy men with high cholesterol (average 272 mg/dL) could actually benefit from drug therapy. Those taking pravastatin (brand name: Pravachol)showed greater reductions in cholesterol, nonfatal heart attacks, and cardiovascular death.

Unlike the older drugs, Pravachol did not produce a higher rate of noncardiac mortality (New England Journal of Medicine, 16 November 1995). it should be noted, however, that this trial did not last longer than five years and the overwhelming majority of its participants were smokers.

So after 25 years of cholesterol research, a drug has been found that didn't kill as many healthy men as it saved--at five years, that is. As for the rest of the population, well, the jury. is still out. Not that this stops doctors from prescribing cholesterol-lowering drugs to healthy women, elderly people, and sometimes even children. It's justified by a combination of assumptions and the extrapolation of research results on men to all other people with high cholesterol.

Too often the screening advice to the public precedes hard scientific evidence that the benefit outweighs the risks. Yet such proof is all the more imperative because the nonselective testing of healthy people holds the potential for creating illness where none would ever have existed,

Suggested Reading:
For an historical account of how the public has been oversold on the dangers of cholesterol and the benefits of medical treatment, read Heart Failure by Thomas J, Moore (New York: Simon & Schuster, 1989).

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