Longitudinal study of 40-50 years old men with risk factors, treated for 20 years - impact on mortality and morbidity

This preventive study was carried out during the years 1975-2000. Its aim was to find out the incidence of risk factors (further only RFs) of atherosclerosis in the population, which is generally considered to be mostly endangered by possible complications of atherosclerosis, i.e. in middle-aged men. Further, the impact of treatment influence on the development of these RFs and impact on the health status of examined men, especially on mortality and morbidity caused by atherosclerotic cardiovascular diseases, was monitored.

RFs of atherosclerosis - they accelerate the process of atherosclerosis and origin of their complications (myocardial infarction, cerebrovascular accident and others). Among risk factors belong e.g. factors of life style, laboratory and other anomalies.

Men born during the years 1926-1937, living in 36 medical districts of Prague 2 were ranked into the study. 2 370 men from the election lists were chosen, which was 50 % of men in this age category in Prague 2. 1417 men participated in the entry examination. According to their health status and to RFs presence or absence (smoking, overweight, high blood pressure, hypercholesterolemia, hypertriglyceridemia, untimely death in a family caused by myocardial infarction or cerebrovascular accident) the men were divided in 3 basic groups: the normal group - without any cardiovascular diseases and without RFs, the risk group - without any cardiovascular diseases but with at least one RF and the pathological group - men with already manifest cardiovascular disease (this group was not monitored onward).

Further monitoring was focused mainly on men from the risk group, which were invited for control examinations at least once a year. Men from the normal group were invited once in several years. RFs were influenced mostly non-pharmacologically (without any medications)  - by changing of lifestyle - diet and eating habits, non-smoking, physical activity, reaching of optimal weight and its preservation. Appropriate medications for favourable impact on RFs started to be accessible not until the end of 1980's.

The study proved the high incidence of RFs in middle-aged men (at least one RF was found in almost 2/3 of examined men - according to contemporary opinions there were much more of them - definitions of RFs were too "soft" at that time). We proved that the risk of death of atherosclerotic cardiovascular diseases was increasing significantly with the age and with the increasing number of RFs, found during the first examination. The values of blood pressure and smoking were also dependent on. The risk was inversely fixed with the level of education (the higher the education the lower the risk).

By systematic and regular monitoring and RFs influencing we reached the point that in the monitored group of the risk men the mean values of the total cholesterol were more favourable in a certain period or the mortality on atherosclerotic diseases was lower than in the general Czech population of men of the same age, which were surveyed in the frame of the MONICA international study (also men without RFs were in this general population).

In the course of the study the examination method of demonstration of defective circulation in cardiac blood vessels, the so-called method of mapping of cardiac (electrical) heart potentials on the chest surface was verified. This non-intervention non-invasive method (which does not burden patients by e.g. inserting a catheter into an artery) proved its reason especially in men, which were without any problems so far. In some of them this examination proved a significant disorder of the capillary return of the heart muscle and it enabled their timely treatment by a surgery or dilation of a cardiac artery by a blower.

After the study completion we received information about more than 90 % of originally examined men. The data transfer from a paper form of questionnaires to an electronic form was carried out in the EuroMISE Centre. It enabled to process acquired data not only by basic statistical methods but also by special statistical methods developed in the framework of the grants of the EuroMISE Centre and also by methods of data mining. The results of analyses were presented annually during many conferences in the Czech Republic and also abroad and we published several publications in international journals. By data mining method the study was evaluated during three international working meetings within international conferences on machine learning and data mining - 25 scientific professionals from 11 European countries dealt with the data of the STULONG study.

The STULONG study is in its extent, implementation, data evaluation and results presentation unique not only in the Czech Republic but it is also important in the international forum. The analysis of gained data still continues and it will surely bring further important results, which will help to recognize such a serious disease as atherosclerosis definitely is.