Background: Cardiovascular diseases (CVD) have been the main cause of death in Poland for the last five decades. In 2010, CVD caused 46.0% of all deaths in Poland. An analysis performed using the IMPACT model, have shown that the reduction in mortality due to ischaemic heart disease, which took place in Poland, was primarily a result of lifestyle changes and of changes affecting risk factors in the population of adults. From the perspective of health policy planning it is very important to know the prevalence of CVD risk factors and to be aware of trends in the population.
Aim: The NATPOL 2011 Survey was a cross-sectional observational study aimed to assess the prevalence and control of CVD risk factors in Poland. The aim of this paper is to describe the objectives and methodology of the NATPOL 2011 project.
Methods: The survey was designed as a representative observational study and was carried out on a representative sample of Polish residents aged 18-79 years. The planned size of the research sample was 2,400 subjects. Participants were randomly selected in bundles, in a stratified, proportional draw performed in three stages. The study was composed of a questionnaire interview, blood pressure and anthropometric measurements as well as a blood and urine sample collection. The examination consisted of two visits at subjects' homes and was performed by well-trained nurses.
Results and conclusions: Letters of invitation were sent to 4,420 potential participants. Of those, 786 persons could not be contacted because the addresses were wrong, the respondents resided at an address other than their registered place of residence or, in some cases, the respondents died prior to the survey. Among 3,634 addresses of the persons sampled for the study there were 661 (M: 328, F: 333) "closed doors" (the nurse was unable to contact the respondent during three consecutive attempts) and 560 (M: 295, F: 265) direct refusals. Finally, 2,413 subjects participated in the study and 2,401 of them completed all the procedures in the survey. The data mentioned above give the response rate of 66.4%.The structure of the study sample, including age groups and gender is almost identical to the structure of the adult population of Poland in 2010, according to the Central Statistical Office data. The sample reflected the structure of the adult population quite well, therefore the weights' adjustments calculated for epidemiological analyses were in range from 0.36 to 4.11.