Nov. 29, 2007 -- High cholesterol is a major risk factor for death from heart disease, but its impact on stroke death is less clear, a new analysis combining 61 studies confirms.
In one of the largest evaluations of the research examining cholesterol and mortality ever conducted, researchers found lower total cholesterol to be strongly protective against death from heart attack for both men and women.
Among adults between ages 40 and 89, a reduction in total cholesterol of 39 mg/dL (or 1 mmol/L) was associated with about a 33% reduction in heart disease deaths.
Among those aged 50 to 69 and 70 to 89, respectively, 1 mmol/L lower total cholesterol was associated with 34% and 17% reductions in the risk of death from heart disease.
"The message is clear with regard to heart disease," researcher Sarah Lewington, DPhil, of the University of Oxford, tells WebMD. "If you are at risk for heart disease or have it, the lower your cholesterol, the better."
Cholesterol and Stroke Death
While studies of cholesterol-lowering statin drugs unequivocally show the drugs to be protective against stroke, most observational studies like the ones included in the latest analysis have failed to show a strong relationship between blood cholesterol levels and death from stroke.
Some have even shown low total cholesterol to be associated with an increased risk of death in elderly patients.
"We don't really understand these findings, and they certainly invite future research," Lewington says. "But the evidence from randomized trials clearly shows that lowering cholesterol with statins has a positive impact on stroke risk. No one is saying that lowering cholesterol is bad news for strokes."
The Message to Patients
American Heart Association (AHA) spokeswoman Barbara V. Howard, PhD, says despite the confusing findings, it is clear that keeping cholesterol under control is one of the best ways to avoid heart attack and stroke.
Lewington and colleagues agree that the public health message is unambiguous.
"Treatment should be guided principally by the definitive evidence from randomized trials, [showing] that statins substantially reduce not only coronary event rates but also total stroke rates in patients with a wide range of ages and blood pressures," they write.