Clinical Edge

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Assessing 30-Minute Office BP Monitoring

Ann Fam Med; 2017 Mar/Apr; Bos, Buis

In a primary care setting, automated office blood pressure monitoring during 30 minutes (OBP30) yields considerably lower blood pressure readings than routine office blood pressure (OBP) readings, a recent study found. The study included 201 patients (mean age 68.9 years, 56.7% women) who were referred for OBP30 due to concern about white-coat hypertension. OBP30 is performed with the patient sitting alone for 30 minutes while the blood pressure is measured automatically every 5 minutes, for a total of 7 readings, and the OBP30 is the average of the last 6 BP readings. This has been shown to correlate well with ambulatory blood pressures. The authors compared OBP30 with routine OBP readings and evaluated how OBP30 influenced medication prescribing. Researchers found:

  • The mean systolic OBP30 was 22.8 mm Hg lower than the mean systolic OBP.
  • The mean diastolic OBP30 was 11.6 mm Hg lower than the mean diastolic OBP.
  • In patients with suspected white-coat hypertension (isolated office hypertension), considerable differences between OBP and OBP30 existed, especially in those aged ≥70 years.
  • Based on OBP alone, physicians said they would have started or intensified medication therapy in 79% of the patients. Based on the results of OBP30, physicians started or intensified medications in 25% of the cases.


Bos MJ, Buis S. Thirty-minute office blood pressure monitoring in primary care. Ann Fam Med. 2017;15:120-123. doi:10.1370/afm.2041.


The difference of over 20 mm Hg in systolic BP between routine BP readings causes pause. Approximately 15% of patients with elevated office blood pressures have white-coat hypertension, meaning their blood pressures outside of the office are not elevated. Identifying this group is important, but often challenging. Currently, the easiest and most common method used to identify white-coat hypertension is to ask patients to purchase a home blood pressure monitor and record their blood pressures, morning and later in the day, at home and to bring those values to their next office visit. Alternatively, ambulatory 24-hour blood pressure monitoring can be ordered. This study shows that in selected patients for whom a concern of white-coat hypertension exists, 30-Minute Office BP Monitoring is another way to identify white-coat hypertension and can substantially influence decisions about treatment in a large number of patients. —Neil Skolnik, MD