Introduction:
The major hypertension guidelines suggest methods for diagnosing hypertension by measuring the 24-hour ambulatory blood pressure (ABP) or home blood pressure (HBP) if hypertension is suspected.
Hypothesis:
there is no consensus of cut off values for HBP as the criterion for hypertension and also optimal duration of home blood pressure measurement (HBPM).
Methods:
319 suspected hypertension patients (systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg, average value of three times measurements of blood pressure in the office) were included in four university hospital. The blood pressure (BP) measurement taken by patients in his/her home with HBPM device (Watch BP Home, Microlife, Swiss) and measured three times with one minute interval at morning and evening for 7 days. The 24-hour ambulatory blood pressure measurement (ABPM) was performed by Mobil-O-Graph (IEM. GmbH, Germany). The device was set to obtain BP readings at 30-minute intervals during the day and night. The definition of hypertension was as follows, SBP ≥135 mmHg or DBP ≥85 mmHg for HBPM and SBP ≥130 mmHg or DBP ≥85 mmHg for ABPM. For the analysis for diagnostic accuracy of HBPM, we used ABPM as a reference standard for the diagnosis of hypertension.
Results:
We decided to exclude 53 patients due to dropout or lack of valid BP measurement (valid leadings <70% of tried measurements of ABPM and less than 5-days HBPM). Finally we analyzed BP measurement data of 266 patients. Dropout or invalid BP measurement was more common in ABPM than HBPM. HBP was measured at least 6 days in more than 90% patients and white coat hypertension was diagnosed more frequently in the HBPM. HBPM had a more than 98.6% positive predictive value and 46.8% negative predictive value for the diagnosis of hypertension when put the criteria on ABPM. There are no difference of diagnostic accuracy for the diagnosis of hypertension according to the 5-day, 6-day and 7-day HBPM.
Conclusions:
A 5-day HBPM is enough for the diagnosis of hypertension considering ABPM as a reference. The cut off value of hypertension in HBPM is same to the current guideline values (135/85 mmHg) in this study. HBPM is an effective and available method for the diagnosis of hypertension in suspected hypertensive patients.
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