What is the optimal interval between successive home blood pressure readings using an automated oscillometric device?

OBJECTIVES: To clarify whether a shorter interval between three successive home blood pressure (HBP) readings (10 s vs. 1 min) taken twice a day gives a better prediction of the average 24-h BP and better patient compliance. DESIGN: We enrolled 56 patients from a hypertension clinic (mean age: 60 +/- 14 years; 54% female patients). The study consisted of three clinic visits, with two 4-week periods of self-monitoring of HBP between them, and a 24-h ambulatory BP monitoring at the second visit. Using a crossover design, with order randomized, the oscillometric HBP device (HEM-5001) could be programmed to take three consecutive readings at either 10-s or 1-min intervals, each of which was done for 4 weeks. Patients were asked to measure three HBP readings in the morning and evening. All the readings were stored in the memory of the monitors. RESULTS: The analyses were performed using the second-third HBP readings. The average systolic BP/diastolic BP for the 10-s and 1-min intervals at home were 136.1 +/- 15.8/77.5 +/- 9.5 and 133.2 +/- 15.5/76.9 +/- 9.3 mmHg (P = 0.001/0.19 for the differences in systolic BP and diastolic BP), respectively. The 1-min BP readings were significantly closer to the average of awake ambulatory BP (131 +/- 14/79 +/- 10 mmHg) than the 10-s interval readings. There was no significant difference in patients' compliance in taking adequate numbers of readings at the different time intervals. CONCLUSION: The 1-min interval between HBP readings gave a closer agreement with the daytime average BP than the 10-s interval.