Long-term time-related predictivity of coronary events as a function of a single measurement of serum cholesterol and systolic blood pressure

Objective - To study the ti me-related association of a single measurement of serum cholesterol and systolic blood pressure with the occurrence of a first coronary event in a population sample of middle-aged men. Methods and results - A single measurement of serum total cholesterol and systolic blood pressure (along with age, cigarette consumption, physical activity at work and body mass index as possible confounders) was made in 1,605 coronary disease-free men aged 40-59 belonging to the Italian rural cohorts of the Seven Countries Study. During 25 years of follow-up 353 men developed a first event, that is a coronary death (sudden or not), and definite or possible myocardial infarction. Twenty-five partitioned proportional hazards models were solved, one for each independent year of follow-up, to predict the risk of incident events. Single-year hazard functions, separately for serum cholesterol and systolic blood pressure, were cumulated and smoothed. The resulting curves showed a regularly increasing risk for coronary events. They fit straight lines, with large correlation coefficients for both serum total cholesterol (r = 0.99) and systolic blood pressure (r = 0.99). These slopes were similar to the coefficients estimated by a single proportional hazards model solved for all events during 25 years. Conclusion - A single measurement of serum total cholesterol and systolic blood pressure in middle aged-men maintains a regular and monotonic relationship with occurrence of a first coronary event during 25 years of follow-up.