Low midlife cholesterol levels improve long-term mortality
MedWire News: Low cholesterol levels in middle age are associated with a reduced mortality rate later in life, research shows.
"In fact, a steady, graded relation was found between the life-years gained and the baseline cholesterol value," report Laura Hyttinen (North Karelia Central Hospital, Joensuu, Finland) and colleagues in the American Journal of Cardiology.
In addition, the long-term follow-up study showed that low cholesterol values were associated with better physical functioning in old age.
Previous studies have questioned the benefits of low serum cholesterol levels on total mortality in older adults. High levels of cholesterol are a known risk factor for coronary heart disease in midlife and early old age, but the association is not as clear cut in older adults.
Indeed, some studies have reported an inverse association with cholesterol levels and mortality, with high cholesterol levels in the oldest adults having a protective effect.
To investigate this paradox, Hyttinen and colleagues analyzed data on 3277 male participants of the Helsinki Businessmen Study. All individuals were born between 1919 and 1934, and were followed-up for 46 years or less. Baseline cholesterol levels were assessed between 1964 and 1973, and then again by self-report in 2000.
The mean baseline cholesterol concentration at midlife was 6.5 mmol/l (250.97 mg/dl), and in 2000 it was 5.2 mmol/l (200.77 mg/dl).
A significant association was observed between total mortality and baseline cholesterol levels, with the lowest mortality observed in men with baseline cholesterol levels lower than 4.0 mmol/l (154.44 mg/dl).
Compared with individuals who had the highest cholesterol levels (>9.0 mmol/l [347.49 mg/dl]), the researchers found that those with the lowest levels (<4.0 mmol/l) gained 5.5 years of life.
There were no significant associations between mortality and cholesterol levels measured in 2000, but Hyttinen and colleagues note that 16% of men were using statins in 2000.
The researchers report that individuals with the lowest cholesterol levels in midlife had better physical functioning, as demonstrated by the RAND-36 score, which is used to assess quality of life (QoL).
Previous studies have suggested that low cholesterol levels might impact QoL by causing cognitive decline or impairment, but there was no association between cholesterol levels and mental functioning in the present study.
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