Coronary risk factors predicting early and late coronary deaths

Abstract

Objective: To study the time related association of a single measurement of coronary risk factors with coronary heart disease (CHD) deaths occurring during a very long follow up period in a population sample of middle aged men.

Design, setting, and methods: Age, systolic blood pressure, serum total cholesterol, physical activity at work, body mass index, and cigarette smoking were measured once in 1622 CHD-free men aged 40-59 belonging to the Italian rural cohorts of the seven countries study. During 35 years of follow up 214 men died from CHD (sudden death and definite myocardial infarction). Seven partitioned proportional hazards models were solved, one for each independent five year block of follow up, to predict the risk of CHD death.

Results: The seven, five year partitioned hazard functions were cumulated and smoothed for each risk factor. The resulting curves showed a regularly increasing time trend in risk for coronary deaths as a function of age, serum cholesterol, systolic blood pressure, and cigarette smoking and a regularly decreasing risk for physical activity. The curves fit straight lines, with large squared correlation coefficients ranging from 0.92-0.97. This suggests a relatively constant strength in the association of risk factor levels with events, which are predicted whatever the length of time after risk factors were measured. These findings were not altered by adding to the models risk factor changes preceding the quinquennium of death.

Conclusion: A single measurement of some coronary risk factors in middle aged men maintains a regular and almost monotonic relation with the occurrence of CHD deaths during 35 years of follow up.

Figure 1

Cumulated partitioned hazard ratio scores for age in the prediction of deaths from coronary heart disease (CHD) during 35 years. Thick line indicates cumulated partitioned hazard ratio scores; dotted lines indicate upper and lower confidence limits; straight line indicates fitted regression equation.

Figure 2

Cumulated partitioned hazard ratio scores for systolic blood pressure in the prediction of CHD deaths during 35 years. Thick line indicates cumulated partitioned hazard ratio scores; thick dotted line indicates cumulated partitioned hazard ratio scores adjusted for previous risk factor change; dotted lines indicate upper and lower confidence limits; straight line indicates fitted regression equation.

Figure 3

Cumulated partitioned hazard ratio scores for cholesterol in the prediction of CHD deaths during 35 years. Thick line indicates cumulated partitioned hazard ratio scores; thick dotted line indicates cumulated partitioned hazard ratio scores adjusted for previous risk factor change; dotted lines indicate upper and lower confidence limits; straight line indicates fitted regression equation.

Figure 4

Cumulated partitioned hazard ratio scores for physical activity in the prediction of CHD deaths during 35 years. Thick line indicates cumulated partitioned hazard ratio scores; dotted lines indicate upper and lower confidence limits; straight line indicates fitted regression equation.

Figure 5

Cumulated partitioned hazard ratio scores for body mass index in the prediction of CHD deaths during 35 years. Thick line indicates cumulated partitioned hazard ratio scores; dotted lines indicate upper and lower confidence limits; straight line indicates fitted regression equation.

Figure 6

Cumulated partitioned hazard ratio scores for cigarette consumption in the prediction of CHD deaths during 35 years. Thick line indicates cumulated partitioned hazard ratio scores; dotted lines indicate upper and lower confidence limits; straight line indicates fitted regression equation.