Cholesterol levels linked to cardiovascular mortality, not stroke-related deaths

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Dec. 6 – Cholesterol levels are closely linked to cardiovascular mortality, especially among middle-age patients, but not to stroke-related deaths, according to a study published in the Dec. 1 issue of The Lancet.

Sarah Lewington, DPhil, of the University of Oxford, and colleagues, reported that for every 1 mmol/L decrease in cholesterol, ischemic heart disease mortality dropped by half among patients ages 40 to 49, by a third among those 50 to 69, and by a sixth among those 70 to 89.

The researchers examined 55,000 vascular deaths from 61 prospective studies during 11.6 million person-years of follow-up for patients ages 40 to 89 without baseline disease.

The mean total cholesterol measurement at baseline was 5.8 mmol/L, and the mean HDL cholesterol was 1.4 mmol/L and the mean total-to-HDL cholesterol ratio was 4.6.

Regardless of cholesterol level after adjustment for age, sex, and study, systolic blood pressure increased about 2.4 mm Hg per 1 mmol/L increase in total cholesterol.

For ischemic heart disease (IHD) mortality, every 1 mmol/L decrease in total cholesterol cut mortality 56 percent for participants ages 40 to 49, 34 percent for those 50 to 69 and 17 percent in those 70 to 89.

The researchers said the total stroke mortality and ischemic stroke mortality were weakly associated with increasing total cholesterol only among middle-age patients (ages 60 to 69). Each 1 mmol/L of total cholesterol was associated with about 2 mm Hg systolic blood pressure, which was associated with a similar stroke hazard ratio of about 0.92 for the same age group.

The total cholesterol was positively associated with IHD mortality in both middle and old age and at all blood pressure levels. The absence of an independent positive association of cholesterol with stroke mortality, especially at older ages or higher blood pressures, is unexplained, and invites further research.

Nevertheless, the researchers concluded that there is definitive evidence from randomized trials 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.