Cholesterol and mortality. 30 years of follow-up from the Framingham study.
Level 3 - non-randomized controlled study
Prospective longitudinal cohort study
PubMed 3560398 · doi:10.1001/jama.257.16.2176
What was done
Between 1951 and 1955, serum cholesterol levels were measured in 1,959 men and 2,415 women aged 31 to 65 years who were free of cardiovascular disease and cancer at baseline, with mortality tracked over 30 years of follow-up in the Framingham Study.
What was found
In participants under age 50 years, baseline cholesterol levels were directly related to 30-year overall and CVD mortality, with overall mortality increasing by 5% and CVD mortality increasing by 9% for each 10 mg/dL increase in cholesterol. In participants aged 50 years and older, there was no increased overall mortality with either high or low baseline cholesterol levels. However, falling cholesterol levels over the first 14 years were directly associated with mortality over the following 18 years, showing an 11% increase in overall death rate and a 14% increase in CVD death rate per 1 mg/dL per year drop in cholesterol.
Why it matters
This study shows that the association between serum cholesterol and mortality is age-dependent and suggests that falling cholesterol in older adults may be a marker of underlying illness rather than an independent protective factor.
Limits
The study is observational and cannot demonstrate causality. Specific causes of falling cholesterol and subfractions like HDL and LDL were not characterized in the abstract. Potential confounding by terminal or chronic illnesses leading to reverse causation in older age groups is a significant limitation.
Cited by
- context In the Framingham Heart Study, after age 50, mortality increased as total cholesterol dropped.