Ambulatory blood pressure reproducibility and application of the method in a healthy Finnish cohort

The aim of the present study has been to study the reproducibility, validity and normal values of ambulatory blood pressure measurement in a healthy Finnish cohort. The reproducibility of ambulatory blood pressure monitoring was examined in healthy volunteers and normal values were determined in a Finnish cohort of males and women of different ages. In the reproducibility study the recording was repeated at 2-week intervals. In the validity study simultaneous measurements were done manually with a mercury sphygmomanometer and compared with the measurement by the ambulatory blood pressure recording unit, both connected with the cuff by a T-tube; this study included 100 consecutive measurements in a patient group. A relatively small cohort was taken from the normal value study group. In addition to ambulatory blood pressure their left ventricle mass was also determined by echocardiography. The correlation between manual blood pressure measurement and simultaneous measurement by the ambulatory blood pressure unit was 0.98. In the reproducibility study the correlations between the two 24-h measurements 2 weeks apart were also good. Depending on the parameter (daytime, nighttime or 24-h blood pressure mean, systolic or diastolic values) the correlation coefficient varied between 0.81 and 0.91. Thus both systolic and diastolic blood pressures, whether expressed as 24-h averages and daytime or nighttime averages, correlated well between these two recording sessions. The data obtained in the present Finnish cohort were well within the published reference value limits, showing only fairly modest age-dependence appearing at quite an old age. There was no significant correlation between the left ventricle mass and ambulatory blood pressure values in a population having normal blood pressure. The results suggest good intra-individual correlation and reproducibility in ambulatory blood pressure monitoring, suggesting this method to be useful in the monitoring of individual blood pressure levels. The validity of the method is good and the published reference values can be applied with reasonable reliability in different populations. In an adult population with normal blood pressure, no correlation between left ventricle mass and blood pressure values can be found, suggesting this correlation may first appear in cohorts including persons with elevated blood pressure values.