Comparison of blood pressure measurement methods in adult diabetics

There was a close correlation between the two methods (r=094 systolic BP, r084 diastolic BP). To further assess DIN accuracy, a measure of agreement was obtained by plotting the difference between the methods against their mean.' The mean (SD) of the means of differences between RZ and DIN for systolic BP was -218 (887) and for diastolic BP +448 (6.01) mm Hg. The limit of agreement (mean [2 SD]) for systolic BP measurement ranged from +1556 to -1991 mm Hg and for diastolic BP from +165 to -7-54 mm Hg. From these data we estimated that for 95% of subjects the DIN measurement of systolic BP and of diastolic BP will be between 16 mm Hg below and 20 mm Hg above and 16 mm Hg below and 8 mm Hg above the RZ measurement, respectively. Whereas these mean differences were constant over the whole range of pressures for diastolic BP the same was not true for systolic BP. When the distribution of systolic BP values was divided in tertiles it became apparent that DIN was significantly overestimating systolic BP for values below 118 mm Hg and underestimating for values greater than 152 mm Hg (p