Low cholesterol, a key health objective for reducing cardiovascular disease, could be associated with higher death-rates among elderly people, conclude authors of a study in this week’s issue of The Lancet.
High blood cholesterol concentration is directly related to mortality for people under 65 years of age. However, previous clinical trials have not included large numbers of patients aged older than 70 years, and researchers have been unable to conclusively show this relation in elderly people.
In a longitudinal population study (part of the Honolulu Heart Program, a large epidemiological study of cardiovascular disease), Irwin Schatz and colleagues from the University of Hawaii studied data (fat and blood cholesterol concentrations) of around 3,500 Japanese/American men who were aged 71-93 years in the early 1990s.
The investigators compared cholesterol concentrations with measurements taken 20 years previously. Death from all causes in relation to cholesterol concentration was calculated using three different statistical assessments.
Overall, average cholesterol concentrations decreased with increasing age of individuals in the study population. Individuals were divided into four quartiles according to blood cholesterol concentrations: 1st quartile 2.09-4.32 mmol/L; 2nd quartile 4.33-4.86 mmol/L; third quartile 4.87-5.43mmol/L; fourth quartile 5.44-9.88 mmol/L.
Lower cholesterol concentration was associated with increased death rates; age-adjusted mortality rates were 68.3, 48.9, 41.1, and 43.3 per 1,000 population per year for the first to fourth quartiles of cholesterol concentrations, respectively. Men in quartiles 2, 3, and 4 had reduced death-rates of 28%, 40%, and 35% respectively compared with men in the first (lowest cholesterol concentration) quartile.
Irwin Schatz comments: “Our data accord with previous findings of increased mortality in elderly people with low serum cholesterol, and show, for the first time,that long-term persistence of low cholesterol concentration actually increases risk of death.
"These data cast doubt on the scientific justification for lowering cholesterol to very low concentrations (less than 4.65 mmol/L) in elderly people.”
[Contact: Dr. Irwin Schatz]