How well does monitoring blood pressure for 30 minutes in the office compare with a single office reading in patients suspected of having white coat hypertension?

In this study in a single practice, monitoring blood pressure readings in the office for 30 minutes resulted in markedly lower readings compared with the last office reading (~ 23/12 mm Hg lower) and the clinicians report they would be much less likely to intensify treatment if they used these readings. It remains to be seen whether this result occurs in other settings or whether patient outcomes are improved. (LOE = 2b)

Bos MJ, Buis S. Thirty-minute office blood pressure monitoring in primary care. Ann Fam Med 2017;15(2):120-123.  [PMID:28289110]

Cross-sectional

Self-funded or unfunded

Outpatient (primary care)

This study took place over a 6-month period in a single primary care practice in the Netherlands. The authors recruited every patient who underwent 30-minute office blood pressure monitoring (OBP30) for medical reasons. For the OBP30 the patient sits alone in a quiet area with an automated unit that measures and records blood pressure every 5 minutes. The final OBP30 reading is the simple average of the 6 readings. For this study, the authors compared the OBP30 with the last "regular" office reading. They also asked the clinician a bunch of questions about why they ordered the OBP30 and how they would use the information. Almost 60% of the 201 patients in this study were women with an average age of 69 years. The authors report that approximately 20% of the patients had diabetes and 20% had cardiovascular disease, but they don't report how many had hypertension. The most common reasons for ordering the OBP30 included suspected white coat hypertension, newly diagnosed hypertension, inconsistent office readings, and monitoring medication effectiveness. On average, the systolic OBP30 readings were 23 mm Hg lower than the office readings, and the diastolic OBP30 readings were 12 mm Hg lower than in the office. For the patients with suspected white coat hypertension, the differences were 30 mm Hg and 14 mm Hg, respectively. For each of the other various categories of clinical circumstances, the differences between OBP30 and the office readings ranged from 14 to 28 mm Hg and 8 to 17 mm Hg, respectively. Approximately 80% of the clinicians would have intensified treatment based solely on the office blood pressure readings compared with only 25% who would have intensified treatment based on the OBP30. This is a cute little study, but I am not sure how to apply this. The existing data of treating hypertension are based on a diagnosis established after 3 elevated readings on separate occasions, and a few studies have suggested that white coat hypertension is not an altogether benign condition.