A new study suggests that among elderly patients being treated for hypertension, blood pressure measurements taken at home may more accurately predict cardiovascular events than those taken in a clinician's office.

Researchers compared the efficacy of home and office blood pressure measurements in predicting cardiovascular "events," such as cardiovascular mortality, myocardial infarction, stroke, angioplasty, and coronary artery bypass graft surgery, in 4,939 patients (mean age, 70 years) being treated for hypertension by general practitioners in Europe. The mean values of six valid measurements taken during two office visits and six valid measurements taken at home (three in the morning and three in the evening), along with other pertinent information such as cardiac risk factors, were established as baseline readings.

After a mean follow-up period of 3.2 years, 205 patients (4.16%) had died, 85 of them (1.72%) of cardiovascular causes; and 324 patients (6.57%) had suffered at least one cardiovascular event. After adjusting for various cardiac risk factors, an analysis using the home blood pressure measurements showed that the risk of a cardiovascular event increased by 17.2% for every 10-mmHg increase in systolic blood pressure and by 11.7% for every 5-mmHg increase in diastolic blood pressure, a pattern that wasn't evident when office blood pressure measurements were used. And in comparison with patients with controlled hypertension (defined as normal home and office blood pressure readings), patients with uncontrolled hypertension (defined as in-office blood pressure readings of at least 140/90 mmHg and home readings of at least 135/85 mmHg) had nearly double the risk of a cardiovascular event; those with elevated home but normal office measurements had more than double that risk. Patients with elevated office but normal home measurements showed no difference in risk.

In light of these results and the fact that office measurements failed to identify a significant proportion of patients with elevated blood pressure levels, the researchers suggested that home measurements should be part of the management of hypertension. -Julie J. Chu, MSN, CRNP

Bobrie G, et al. Cardiovascular prognosis of "masked hypertension" detected by blood pressure self-measurement in elderly treated hypertensive patients. JAMA 2004;291(11);1342-9.