Methodological aspects of health evaluation of the population suffered after the Chernobyl catastrophe

Ecological situation in Belarus and the necessity of liquidation of medical consequences of the Chernobyl NPP Catastrophe demand many years' dynamic observation after the health condition of large people's contingents. At present this problem is being solved by the clinical follow up of the population undergone irradiation due to the Chernobyl catastrophe which is the basis of medical-prevention measures, directed to low medical consequences of the Chernobyl catastrophe. All the information on population's health received during the clinical follow up is put to a special State Data Base which was started for a clinical follow op information support, carrying out scientific researches and receiving reliable data on medical- biological consequences of the Chernobyl catastrophe. At present there's a problem of correct evaluation of health changes of the population who need clinical follow up on all its levels. The problem of comparative analyses of stored data hasn't been solved yet. It's necessary to underline that illness data of the population suffered after the Chernobyl catastrophe received due to intensive clinical follow up can't be compared with illness data of the population in general received due to ordinary applies to hospitals. It would be methodologically incorrect. Besides all said above, including into the research all the classes and forms of illnesses according to IDC-9, IDC-10 (International Disease Classification 9,10) what in a great degree enlarges volume of the research and its expenses is irrational. While studying the Chernobyl catastrophe medical consequences one must include to the analysis classes and nosologic illness forms which level and dynamic changes connected in some extend to radiation irradiation. By doing this one can minimize the volume and the expenses in the research like this. In this situation it's necessary to state such population health indexes which level exposed to a distortion in the lowest degree in the result of different revelation systems. We think it's possible only when there are cases of so called modification, t. i. when there are only two outcomes (dead or not dead, fell ill or not and so on). This is related to death indexes and to those diseases which one cad develop just once (for example malignant tumor). Besides all the malignant tumor cases and cases ended in patient's death are very strictly counted on the territory of Belarus and their number doesn't depend on revelation system. Studying the health indexes of the population suffered after the Chernobyl catastrophe will let us find an adequate control group which will be not only age representative but revelation system representative as well. While choosing a control group especially while studying level of malignant tumor, the essential corrections must be made because of a difficult migration process after the Chernobyl catastrophe. First of all, people who took part in the activities related to the liquidation of the consequences of the catastrophe and those who were evacuated due to the law called 'Social Protection of the Population Suffered after the Chernobyl Catastrophe' must be excluded from the group. Secondly, a great attention must be paid to age-sex studying of the population structure and the changes taking place in this group due to a migration process. The research carried out earlier showed that for studying medical consequences of the Chernobyl catastrophe a control group should be chosen from the population living in Vitebsk region as it suffered in the least extent. Essential differences in sex-age structure of the population suffered after the catastrophe demand the necessity of carrying out a comparative analysis only with the usage of standard indexes. For carrying out an epidemiological research it's not enough to have a control group, which differs from the others just due to the degree of a risk factor affect. The most important thing is absence of authentic differences in the initial levels of a sickness rate between the studied groups. That is why carrying out a sickness rate comparative analysis in the studied groups referred to a before catastrophe period (before 1986) or to a so called latent period (according to literary data this period is 5-10 years, t.i. 1990-1996) must be planed for a choice of an adequate population control group. The absence of initial differences on authentic levels and in dynamics of a sickness rate referred to before catastrophe period between the compared groups let this chosen population group be an adequate form of control. Besides while choosing a control group other 'interfering'. Factors like social-economical, demographical, geographical conditions must be taken into account. While studying a sickness rate of the population which lives on radio affected territories one could compare a sickness rate only inside this group in before catastrophe period (before 1986) and after. One should take into consideration, that while sickness rate comparing after 5, 10, 20 years, an essential influence on a sickness rate has changing diagnostic methods, classification and illness description, new screening programs and maximum doctors' attention towards detecting some illnesses. That is why carrying out the research on health condition of the population after the catastrophe according to the plan 'before-after' is inexpedient and will lead to insurmountable problems when finding out the degree of reality and comparativeness of initial data. (Authors)