Blutdruckmessung in der NAKO - methodische Unterschiede, Blutdruckverteilung und Bekanntheit der Hypertonie im Vergleich zu anderen bevölkerungsbezogenen Studien in Deutschland [Blood pressure measurement in the NAKO German National Cohort (GNC) - differences in methods, distribution of blood pressure values, and awareness of hypertension compared to other population-based studies in Germany]

BACKGROUND: Arterial hypertension is animportant risk factor for cardiovascular diseases. Epidemiological studies typically perform three consecutive blood pressure measurements. The first measurement is discarded in subsequent analyses, as this value may be strongly affected by previous activities. Due to time constraints the German National Cohort (GNC NAKO) performed only two blood pressure measurements. OBJECTIVES: The present analysis examined the possible effects of methodological differences in blood pressure measurement by comparing the first 101,816 GNC participants (two blood pressure measurements) with those of five German population-based studies (three measurements). MATERIALS AND METHODS: Blood pressure data from participants aged 20 to 79 years from the GNC, the German Health Interview and Examination Survey for Adults by the Robert Koch Institute (DEGS1), and four regional population-based cohort studies (CARLA, HNR, KORA, SHIP) were used to calculate age- and sex-specific mean blood pressure values and hypertension frequencies based on the second blood pressure measurement, the arithmetic mean of the first and second value and of the second and third (the latter not available in the GNC). RESULTS: The mean blood pressure values of the two most recent studies (GNC, DEGS1) were very similar and lower than in the other studies. The difference of the second measurement and the mean of second and third measurement was small (maximum mean difference: 1.5mm Hg systolic blood pressure), but leads to higher estimated hypertension frequencies. CONCLUSIONS: The current results show that using the second blood pressure measurement should be recommended for scientific analyses of GNC data.