Which measurement of home blood pressure should be used for clinical evaluation when multiple measurements are made?

OBJECTIVE: We evaluated which home blood pressure (BP) measurement was most useful in clinical evaluation when we measured it three times per sitting. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.