Przegla̧d lekarski
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One of the frequently encountered problems in the statistical analysis of the data is the correct interpretation of the effects occurring under the influence of some kind of treatment used by the researcher or appearing without its share of action. In the first case we are dealing with an experimental study, in the second with the observational study. ⋯ In the case of an observational study, also called a retrospective study there are often additional factors that modify both assigned to the same groups as well as specific actions for the test results. The article presents an example of the cause of this phenomenon and selected methods of minimizing the mentioned influence.
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Epidemiology of acquired valvular heart diseases has changed significantly over last decades. Degenerative aortic valve stenosis is the most common acquired valvular disease with high prevalence in elderly population. Another common disorder is ischemic mitral regurgitation secondary to myocardial infarction. ⋯ Discussion about pregnancy should be a part of management of young women with valvular heart disease. Severe valve disorders should be corrected when planning pregnancy. The final management should always be based on collaborative decision made by the patient and health professionals.