Multi-centre National Population Health Examination Survey (WOBASZ II study): assumptions, methods, and implementation.

BACKGROUND: Cardiovascular diseases (CVDs) are the main cause of morbidity and mortality in developed countries. Despite the progress in diagnostics and treatment, it is expected that CVD will still be the main cause of death worldwide until at least 2030. From 1991 CVD mortality in Poland systematically decreased, but it is still higher than the average in Western Europe. In 2013 CVDs were the cause of 46% of all deaths in Poland (40.9% in men and 51.1% in women) and 26.9% of deaths among persons under 65 years of age. The epidemiologic assessment of prevalence, control and treatment of CVD risk factors, and monitoring of healthy behaviour and morbidity due to diseases like coronary artery disease, hypertension and diabetes is very important for health policy planning. The WOBASZ II is the newest Polish population based survey, performed in 2013-2014 to evaluate prevalence, control, treatment, and morbidity. The study was the continuation of WOBASZ (2003-2005). AIM: To describe the goals and methods of the WOBASZ II study and to present the results of the recruitment.
METHODS: The WOBASZ II study was planned as a cross-sectional survey of a random sample of Polish residents aged over 20 years. The selection, using the National Identity Card Registry of the Ministry of Internal Affairs, was made as a three-stage sampling, stratified according to administrative units (voivodeships), type of urbanisation (commune), and gender. The study protocol consisted of a questionnaire used in face-to-face interviews, physical examination, and blood samples. WOBASZ II was coordinated by the Department of Epidemiology, Cardiovascular Diseases Prevention and Health Promotion of the Institute of Cardiology in Warsaw in cooperation with medical universities in Gdansk, Katowice, Krakow, Lodz, and Poznan.
RESULTS: Out of 15,120 persons, 1557 persons were not eligible. Out of eligible persons, 6170 (2760 men and 3410 women) were examined (the response rate 45.5%). The highest response rates were observed in Warminsko-Mazurskie (64.2%), Zachodniopomorskie (58.1%), and Kujawsko-Pomorskie (53.1%).
CONCLUSIONS: The importance of the WOBASZ study for the monitoring of the health state of Polish society, and for the as-sessment of prophylaxis efficiency and treatment of CVD and metabolic diseases, as well as for the evaluation of the actions in the field of health promotion, is difficult to overstate.