Coronary heart disease in 'low risk' men

An attempt was made to explore the reasons why men develop coronary heart disease (CHD) despite being at low risk on the basis of established risk factors. A case control study was designed to take place after the end of a longitudinal study in which both low- and high-risk men who had developed CHD over the course of 5-6 years were compared with controls who had remained CHD-free, matched for initial risk characteristics. Low-risk men who had developed CHD had significantly lower levels of high density lipoprotein (HDL) cholesterol than their controls. This difference was not seen when high-risk men were compared with their controls. Apart from a suggestion that low risk cases had lower levels of free thyroxine (seen mainly when less severe categories of CHD were examined) there were no other significant differences between cases and controls (either low- or high-risk) in the other measured variables, which included levels of total testosterone and oestradiol in plasma, packed cell volume and heart rate. It is concluded that low levels of HDL cholesterol may partly explain why men who are otherwise at low risk develop CHD. This study design may be useful to test other hypotheses, particularly where it has not been possible to make the appropriate measurements at the start of a longitudinal study.