Despite frequent abnormalities in glucose metabolism, elderly patients with low cholesterol absorption appear to have a survival advantage. "Our finding is intriguing," said lead investigator, Dr. Timo E. Strandberg, "and shows new relationships between cholesterol and glucose metabolism in the elderly, also related to survival."
"Diabetes and the metabolic syndrome are harmful," he added, "even in the elderly, but their harmful effect may be modulated by cholesterol metabolism."
Dr. Strandberg of the University of Oulu and colleagues studied 247 women and 129 men with cardiovascular disease. All of the subjects were age 75 years or older and lived at home.
There were 64 deaths over 3.4 years of follow-up. Serum total and LDL cholesterol levels did not predict outcome. However, the mortality risk increased with increasing cholestanol to cholesterol ratios, a measure of cholesterol absorption. Cholestanol is a byproduct of the reduction of cholesterol.
Although 50% of subjects with the lowest ratios had the metabolic syndrome or diabetes, those with the highest ratio had a relative hazard ratio for death of 2.54.
Moreover, the lowest values were independently associated with fewer major cardiovascular events (relative hazard ratio, 0.59) as well as reduced mortality (relative hazard ratio, 0.37).
One explanation of these findings, said Dr. Strandberg, is that "cardiovascular risk factors kill susceptible people in mid-life, before they get old; survivors to old age are more or less resistant, for example, because of protective factors."
"As a result," he added, "we may see a paradoxical relationship between an established risk factor in mid-life — such as cholesterol — and survival in old people."
As always, Dr. Strandberg added, "further studies are needed. We are currently performing them in another group of people, in whom we have measured glucose, cholesterol absorption and synthesis earlier in life and followed their mortality to old age."
J Am Coll Cardiol 2006;48:708-714.