Prevalence of ischaemic heart disease and associations with serum lipoproteins in subjects aged 45 to 64 years. The Speedwell study.

A longitudinal study has been set up to examine the incidence of ischaemic heart disease and its associations with serum lipoproteins including high density lipoprotein cholesterol and its subfractions, certain haemostatic factors, and other "risk' factors. We report here on our pilot study findings. Cross-sectional data were available on 283 men and 68 women aged 45 to 64 representing 85% of the available population randomly selected from the lists of 16 general practitioners. Reproducibility of the measurements of total serum cholesterol, triglyceride, and low density lipoprotein cholesterol was acceptable. The reproducibility of some of the other serum lipid fractions, for example high density lipoprotein cholesterol, was less good, in part because of the small range of the values found for these components. Univariate associations of physical and behavioural characteristics and serum lipoproteins of men and women, with and without ischaemic heart disease, disclosed small and statistically nonsignificant differences except for levels of blood pressure. In particular, there was no significant difference in mean levels of serum high density lipoprotein cholesterol between men with ischaemic heart disease (0.91 mmol/l) and men without it (0.94 mmol/l). In examining our data for the determinants of serum high density lipoprotein cholesterol using a linear multiple regression model, sex, serum high density lipoprotein cholesterol, and very low density lipoprotein triglyceride were the major factors, each individually explaining about 7% of the variance of serum high density lipoprotein cholesterol levels. In addition, alcohol intake and obesity each explained a further 2% of the variance. The experience of the pilot study has led to modifications in the collection of blood samples and the subsequent estimation of lipid fractions.