[Is masked hypertension an artefact due to the blood pressure measurement method and threshold effects?]

From results of office and home measurements of blood pressure (BP), patients can be classified as "hypertensive (HT)", "normotensive (NT)", "office hypertensive (OH)" or "masked hypertensive (MH)" by crossing the classifications obtained from each method. It seems that 9 to 20% of patients could be MH with a prognosis close to HT (SHEAF study).

To test the hypothesis that at least one part of the prevalence of MH would be an artefact due to the difference between the methods of measurements (shygmomanometer vs semi-automatic device) and/or due to different definitions of office hypertension (OHT). To determine the impact of different definitions of OHT on the prevalence of MH.

During the course of a phase IV study, BP was measured with the same semi-automatic device (OMRON 705CP) both at doctor's office (3 measurements at 1-minute intervals) and at home, by the patient himself (3 measurements in the morning and in the evening at 1-minute intervals over the 7 days before the visit). Following definitions were used: Office HT: SBP > or =140 mmHg, DBP > or =90 mmHg, SBP > or =140 mmHg or DBP > or =90 mmHg; Home HT: SBP > or =135 mmHg, DBP> or =85 mmHg, SBP > or =135 mmHg or DBP > or =85 mmHg. Another definition of office HT was used SBP > or =135 mmHg, DBP > or =85 mmHg SBP > or =135 mmHg or DBP > or =85 mmHg.

575 patients were analysed. Results from the two methods of measurements are closed but significantly different (difference for SBP: 3.2 +/- 16.5 mmHg; p < 0.0001; difference for DBP: 1.4 +/- 10.3 mmHg; p = 0.002)