The results from Helsinki Coronary Register during the period 1970-1977 show that the incidence of acute myocardial infarction (AMI) among people under 65 years of age reached its peak in 1972 and declined annually by 2.8% from 1972 to 1977. The trend was clearest in patients under 50 years, but statistical analysis showed that no 5-year age group, either in women or men, differed statistically significantly from the general declining trend.
Based on the Finnish Register of Congenital Malformations a search was undertaken for associations between defects of the central nervous system [CNS] and various selected risk indicators. The study material consisted of 710 cases of CNS defects and their time-area matched pair controls. 259 cases of polydactyly and their controls were also compared with a view of demonstrating the possible biases introduced by the case-control method. The present report is a multivariate analysis of previously observed associations, and the linear logistic regression model was used for the elimination of confounding factors. Risk indicators remaining after the analysis were high maternal age, multipara with previous stillbirths and defective children, especially defects of the CNS. Maternal influenza, especially in combination with the intake of salicylates, was also associated with an increased risk.
Smoking history, systolic blood pressure, and serum cholesterol concentration were studied for their value in predicting 5-year coronary mortality in middle-aged and older Finnish men. Total experience consisted of 188 deaths from ischemic heart disease during 20,245 person-years. Initially, the men were divided into 3 groups according to the degree of myocardial ischemia: (1) previous myocardial infarction; (2) ischemic heart disease without infarction; and (3) no myocardial ischemia. The 3 main risk factors were associated, independently of each other and of age, with the relative risk of coronary death similarly in the 3 groups, whereas their absolute impact on mortality was strong among men with ischemic heart disease and even stronger among those with a prior myocardial infarction. For example, the estimated excess coronary mortality attributable to smoking 10 to 19 cigarettes per day was 6.3 deaths per 1,000 person-years in the group with no ischemia, 14.6 in the ischemia group, and 43.1 in the infarction group. The results suggest that secondary prevention of ischemic heart disease may be important. Screening of coronary disease among middle-aged and older men also appears justified.
In 1970 the Helsinki Coronary Register gathered data on 1191 AMI cases and 470 deaths from AMI of Helsinki residents under 65 years of age. Since then the mortality (deaths within the first 28 days per 1000 habitants of Helsinki) from AMI declined by 1.8% a year during the period 1970-1977, and there were no statistically significant differences in trends between women and men, or between different age groups (P greater than 0.10). The case fatality rate varied from 39% in 1970 to 35% in 1977, and the statistical analysis could not reveal any significant permanent decreasing trend in any age or sex group. These results, together with our previously reported AMI incidence trends, show that at least in 1970-1977 the declining trend in mortality from AMI was due to an equal fall in the incidence of AMI. Therefore there is reason to think that the effect is due to the prevention of AMI, rather than to more effective acute care.
In the Helsinki Policemen Study based on a cohort of 982 men aged 35-64 years and free of coronary heart disease (CHD) at entry plasma insulin level (fasting, 1-hour and 2-hour plasma insulin after oral glucose load) showed during a 9 1/2-year follow-up a non-linear association to the incidence of "hard criteria" CHD events (CHD death or non-fatal myocardial infarction) with highest incidence in the top decile of plasma insulin. Plasma insulin levels showed positive correlations, besides to blood glucose levels, to body mass index, plasma triglyceride level and blood pressure and inverse correlations to leisure time physical activity and objectively measured physical fitness. In multivariate analyses the predictive value of high plasma insulin with respect to CHD risk was found to be independent of other risk factors, including blood glucose levels.
The reproducibility and validity of a food frequency questionnaire designed to measure intakes of total fat, saturated and polyunsaturated fats, vitamins A, C, and E, selenium, and dietary fiber were tested from March to October 1984 among 297 Finnish men aged 55-69 years. The questionnaire asked about consumption of 44 food items. In the reproducibility study, 107 subjects filled in the questionnaire three times, at three-month intervals. Intraclass correlations varied from 0.52 for vitamin A to 0.85 for polyunsaturated fat. In the validity study, 190 subjects kept food consumption records for 12 two-day periods distributed evenly over a period of six months and filled in the questionnaire both before and after this period. Correlations between the nutrient intake values from the food records and those from the food frequency questionnaires ranged from 0.33 for selenium to 0.68 for polyunsaturated fat. On the average, 40-45% of the subjects in the lowest and highest quintiles based on food records were in the same respective quintiles when assessed by the food frequency questionnaire, and 70-75% were in the two lowest and two highest questionnaire quintiles, respectively. The food frequency questionnaire and a quantitative food use questionnaire tested in the same study were compared. Use of these two instruments in large-scale epidemiologic studies is discussed.