An ecological study of serum cholesterol and ischaemic heart disease between 1950 and 1990

Abstract

Objective: (i) To carry out a quantitative analysis of the average serum cholesterol levels in different countries in relationship to the ischaemic heart disease (IHD) mortality in these countries. (ii) To examine changes in serum cholesterol levels over time in different countries.

Design: Analysis of published surveys measuring average serum cholesterol in specified communities in different countries.

Setting: The original cholesterol surveys were mainly in occupational and residential settings.

Results: Survey data allowed estimation of average serum cholesterol levels during specified time periods for 17 countries; estimates in men aged 40-59 years varied from 3.8 mmol/l (rural China) to 7.0 mmol/l (Finland). Variation in serum cholesterol accounted for 80% of the tenfold range in risk of IHD across countries. A difference in total (or LDL) cholesterol of 0.6 mmol/l between countries was associated with an average difference in IHD mortality of 37% at age 55-64 years. Repeat surveys showed that serum cholesterol reductions of the order of 0.6 mmol/l have occurred in some communities over about 5-10 years.

Conclusions: Variation in serum cholesterol explains four-fifths of the geographical variation in IHD mortality. Reductions in cholesterol of about 0.6 mmol/l (10%) have been achieved in some Western communities or countries over periods of a few years, a change that is associated with a decrease in IHD mortality of over one-third.