Occupation and pathology of the cardiovascular system: factors that modify the causal relations in epidemiological studies

In scientific terms, the protection of workers' health is based on evidence of causal links between occupational factors and the onset of illness (or fatal case). The review considers the factors that modify the causal relations between occupational exposures and pathology of the cardiovascular system of workers in epidemiologic studies. Analysis of published data shows strong role of modifying impact of traditional risk factors, and healthy worker effect in shaping of the levels of cardiovascular disease in the working population. This modifying effect needs to be identified and eliminated at the moment of the analysis of the causal relations between occupational exposure and the development of diseases. Some of the most common methodological mistakes are presented on the example of the concrete case studies: ignoring the traditional risk factors for cardiovascular diseases, considering of correlations of occupational experience with the prevalence of diseases as causal, not as associative (due to age), lack of analysis of the possible occupational selection (artificial or spontaneous) of more healthy workers in poor working conditions. The main directions of methodological approaches of formation of the test samples, the results of analytical and statistical processing techniques eliminating the modifying effect were presented. The author's methodical methods that allow identifying and correction of the modifying effect of the healthy worker effect (healthy hire effect and healthy worker survivor effect) on ​​the relative risk and etiologic fraction of disease in occupational groups on the basis of epidemiological data were highlighted in details. It is noted that a broader and more complete use of the modern developed methodological approaches to the formation of the test samples as well as to the results of analytical and statistical processing techniques, can significantly improve the adequacy and reliability of national epidemiological studies.