Methodological aspects of the design and conduct of preventive trials in ischaemic heart disease

Cardiovascular risk factor changes in a three-year follow-up of a cohort in connection with a community programme (the North Karelia Project)

A re-examination after 3 years was done in 1975 in a 20% random subsample (n = 1683) of the representative population sample (males and females, 25-59 years) that was examined in 1972 in North Karelia (NK), and a matched reference county as the baseline survey for the community programme in NK. The changes in smoking habits, serum cholesterol, dietary fat consumption and systolic BP were more favourable among the subjects in the NK sample than among the reference sample, although the differences were generally small. Results from multivariable analyses are presented to show the variables that predict a favourable risk factor change in the individual. Living in NK is associated in the analysis with a favourable change in each of the three risk factors. The limitation of this method in the evaluation of a community programme is discussed.

Hypertension, cigarette smoking, and the decline in stroke incidence in eastern Finland

Finland has high rates of both cardiovascular disease and cardiovascular disease risk factors. We studied random samples of the population 30-59 years of age for risk factors in two provinces of eastern Finland in 1972 and 1977. We then followed both cohorts until 1985 through linkage with national hospital discharge and death certificate registers. The prevalence of hypertension and smoking in both provinces declined between 1972 and 1977, as did the stroke incidence in the 8-year period of follow-up of each cohort. We observed no differences in stroke incidence between the two provinces. The relative risk of stroke in the later period (1977-1985) was 0.71 and 0.58 for men and women, respectively, when compared with the earlier period (1972-1980). Overall, 28% of all stroke events could be attributed to hypertension, 17% to smoking, and 43% to these two factors jointly. The decrease in the prevalence of hypertension and smoking accounted for about 29% of the decline.

Evaluating community-based preventive cardiovascular programs: problems and experiences from the North Karelia project

Among the different approaches to the study of cardiovascular disease prevention are community-based programs. This type of program concerns a whole community and the intervention takes advantage of the existing service structure and community organization. The evaluation assesses the feasibility, effects on risk factor and disease reduction, costs, process, and other consequences associated with the program. Several such programs have recently been launched in the United States and some other countries. The first major community-based control program was the North Karelia project in Finland, started in 1972 and recently evaluated for its first five-year period. This paper discusses the problems in evaluating community-based CVD control programs on the experiences obtained in the North Karelia project.

Theory and action for health promotion illustrations from the North Karelia Project

The North Karelia Project in Finland illustrates the fundamental goals of health promotion. Specific activities of the project serve as examples of how concepts from the social and behavioral sciences can be applied to achieve estimated reductions in predicted risk of disease. The results in North Karelia are not conclusive, but they are encouraging, and the investigations conducted there is an essential reference for future research in health promotion and disease prevention.

The phenomenon of regression to the mean and clinical investigation of blood cholesterol lowering drugs

The phenomenon of regression to the mean is widespread. It may affect any quantitative biological data in which there is "within subject" variability. It is demonstrated, as an example in practice, by a shift from high to lower values with time in a selected subset of patients with an abnormally high blood cholesterol. The phenomenon will influence experiments involving before-after measurements of a continuous variable. An incorrect conclusion may be reached if investigators do not take regression to the mean into account when designing a clinical trial of hypolipidemic therapy. The reality of the phenomenon is illustrated by a prospective study.