We evaluated which home blood pressure (BP) measurement was most useful in clinical evaluation when we measured it three times per sitting.
Home BP measurements in the morning and evening were performed for 7 days in 572 volunteers (384 men, 188 women, mean age 41.2 years) in 2002 (period 1) and 2003 (period 2). Five sets of measurements were analyzed: A, mean of the first; B, mean of the second; C, mean of the first and second; D, mean of the second and third; and E, mean of all measurements. By analyzing BP in five sets in both periods, their reproducibility was examined.
For all five sets of measurements, little difference was found when BP readings were compared between both periods [the differences were −0.6 ± 6.7 to −0.4 ± 7.0 mmHg for morning systolic BP (SBP), 0 ± 4.9 to 0.3 ± 5.0 mmHg for morning diastolic BP (DBP), −0.1 ± 7.1 to 0.1 ± 7.0 mmHg for evening SBP, and 0.1 ± 5.3 to 0.4 ± 5.4 mmHg for evening DBP]. Furthermore, BP readings between both periods correlated well; the correlation coefficients were 0.90–0.92 for morning BP and 0.86–0.89 for evening BP. In addition, the concordance rates of three BP categories (normotension, borderline and hypertension) were excellent using morning home BP (kappa coefficient 0.64–0.68) in all five sets, and higher than those using evening home BP (0.52–0.57).
This study has shown that even one measurement on each occasion is as useful as several measurements when 7 consecutive days of home BP measurements are used for clinical evaluation.