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Wednesday, January 19, 2011

As We Age, Cholesterol Level Loses Its Value as a Risk Factor

Because both a high total cholesterol level and a high LDL-cholesterol level are risk factors for heart disease, statin drugs, which lower both levels, are widely prescribed. In the U.S., more prescriptions are written for Lipitor, the most popular statin, than for any other drug. Estimates for the number of people who take statins range between 11 million and 30 million. But should so many people be taking statins? A recent analysis, in which scientists reviewed 14 studies that included data from over 34,000 patients, showed little evidence that statins prevent heart trouble in patients with no history of cardiovascular disease. And because there is some evidence linking low cholesterol levels with increased risk of death from other causes, the study authors feel that doctors should be more cautious about prescribing statins.

An important factor to consider when deciding whether or not to prescribe statins is the patient’s age. A study by Kronmal et al., entitled, “Total Serum Cholesterol levels and mortality risk as a function of age” in the Archives of Internal Medicine (vol. 153, pp. 1065-1073, 1993) examined how age affected the ability of cholesterol level to predict the risk of dying, and it showed that the predictive value declined with age.
The most important consideration when judging mortality risk is the overall likelihood of dying from any cause. In that regard, at age 40, those people with higher total serum cholesterol levels had a significantly higher all-cause mortality risk. However, the relationship declined with age, and by age 60, the relationship between total cholesterol level and all-cause mortality had vanished. By age 80, the relationship actually reversed, so that those with higher cholesterol levels were at significantly lower risk of dying.

Looking specifically at the risk of death from coronary heart disease, the death risk at ages 40, 50, and 60 years was greater for those with higher cholesterol levels, although the effect got smaller with age. By age 70, the relationship was still positive but weak, but by age 80 the relationship reversed, and those with higher cholesterol levels actually had less chance of dying.

Looking at death due to causes other than heart disease, (e.g. cancer), from age 50 on, there was a lower risk of dying as cholesterol levels rose. This apparent protective effect of cholesterol against non-heart-disease death increased with age. Seventy-three percent of 80 year-old men with cholesterol levels above 240 survived for 5 years, while only 49% of those with levels below 240 did. The effect was in the same direction but weaker for women, with a 74% and 70% 5-year survival rates for women with cholesterol levels respectively above and below 240 mg/dl. In regard to cancer alone, higher cholesterol level was associated with lower death risk.

Bottom Line
The current practice of the medical establishment of prescribing statins to anyone with a total cholesterol level above 200 appears to be unjustified. For patients with elevated cholesterol levels and a history of heart disease, statins provide a proven reduction in risk. However, for patients with mildly elevated levels and no history or heart disease, the evidence in favor of prescribing statins is weak or nonexistent. And for men above age 70, even those with cholesterol levels above 240, statins could very well increase the risk of death.

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