Objective: The aim of this study was to determine the optimal schedule for home blood pressure (HBP) measurement based on a clinical approach.
Methods: Four hundred and sixty-four participants underwent HBP measurement for 7 days (duplicate measurements in the morning and in the evening), ambulatory blood pressure (ABP) monitoring, and measurement of target organ damage (echocardiography and microalbuminuria). To evaluate the optimal schedule for HBP measurement, correlations of HBP with ABP and HBP with indicators of target organ damage were calculated.
Results: HBP decreased slightly (day 1, 129.9/85.3 mmHg; day 7, 128.6/84.8 mmHg), whereas the association between HBP and ABP or target organ damage increased with the cumulative number of measurements. The highest correlations were obtained by using the mean of all 28 measurements, although no major increase occurred after day 4. There was no change in the correlations when the measurements performed during the first day were discarded. Morning and evening HBP correlated equally well with ABP and microalbuminuria. The mean of the first measurements on each measurement occasion was 2.3/1.2 mmHg higher (P < 0.001 for both) than the mean of the second measurements, but discarding the first measurements did not result in greater correlations. The results were similar in both hypertensive and normotensive populations.
Conclusion: Duplicate measurements on at least 4 days in the evening and in the morning are needed to reliably estimate an individual's BP level and the risk for target organ damage. Measurements performed during the first day should not be discarded, as suggested by the current European guidelines.