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Seasonal variation in plasma cholesterol distributions: implications for screening and referral
L Råstam1, P J Hannan, R V Luepker
1Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis.
Insights
Cholesterol levels show a seasonal trend, peaking in January. This seasonal variation significantly impacts hypercholesterolemia prevalence in men, doubling in winter compared to summer.
Area of Science:
- Cardiovascular Health
- Endocrinology
- Public Health
Background:
- Plasma cholesterol levels are a key indicator of cardiovascular health.
- Seasonal variations in physiological parameters are increasingly recognized.
- Understanding cholesterol trends is crucial for effective public health strategies.
Purpose of the Study:
- To investigate the presence and magnitude of seasonal trends in plasma cholesterol levels.
- To determine if these seasonal trends influence the prevalence of hypercholesterolemia.
- To assess sex-specific differences in cholesterol seasonality.
Main Methods:
- Analysis of plasma cholesterol data from a community-based screening program involving 3,377 men and 3,900 women.
- Statistical analysis to identify cyclic time-trends and peak cholesterol levels.
- Application of National Cholesterol Education Program (NCEP) high cholesterol risk cutoff (< or = 240 mg/dL) to assess prevalence variations.
Main Results:
- A significant cyclic time-trend in cholesterol levels was observed, with a peak in January.
- The peak-to-trough cholesterol difference was 5.8-13.8 mg/dL in men and 2.0-9.3 mg/dL in women.
- Statistically significant seasonal variation in hypercholesterolemia prevalence was found in men (P < .01), with winter prevalence (25.4%) double the summer prevalence (13.5%), but not in women.
Conclusions:
- Seasonal variation is a significant determinant of hypercholesterolemia prevalence in men.
- Healthcare providers should consider seasonal trends in patient follow-up and cholesterol screening.
- Further research may explore the mechanisms behind seasonal cholesterol fluctuations in men.
Abstract:
In 3,377 men and 3,900 women who participated in a community-based plasma cholesterol screening program, we found a significant cyclic time-trend in cholesterol levels, with maximum peak in January. The 95% confidence interval (CI) of the peak to trough distance was 5.8-13.8 mg/dL (0.15-0.36 mmol/L) in men, corresponding to 2.6%-6.3% of the average cholesterol level. Corresponding figures for women were 2.0-9.3 mg/dL (0.05-0.24 mmol/L) or 1.0%-4.6%. Applying the cutoff level for high cholesterol risk proposed by the National Cholesterol Education Program (< or = 240 mg/dL [6.21 mmol/L]) to sex-specific bimonthly distributions, we found a statistically significant variation in prevalence, attributable to seasonal trends, in men (P < .01), but not in women. In men, the age-adjusted prevalence in winter (25.4%) was double that in the summer (13.5%). Seasonal variation is an important determinant of the prevalence of hypercholesterolemia in men and should be considered in patient follow-up and screening.