Ambulatory measurements of blood pressure more strongly predicted all-cause and cardiovascular mortality than did BP measured in the clinic, according to analysis of a large patient registry in Spain.
The results also showed an increased risk of death associated with white coat hypertension and an even stronger association between death and masked hypertension. They were published in the New England Journal of Medicine.
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Previous investigations had found that 24-hour ambulatory BP measurements were better predictors of patient outcomes than those obtained in the clinic or at home, but those investigations were small or population based.“In these studies, the number of clinical outcomes was limited, which reduced the ability to assess the predictive value of clinic blood pressure data as compared with ambulatory data,” reported José R. Banegas, MD, of the department of preventive medicine and public health at the Autonomous University of Madrid and his colleagues.
To better define the prognostic value of 24-hour ambulatory blood pressure measurement, Dr. Banegas and his colleagues looked at data on a large cohort of primary care patients in the Spanish Ambulatory Blood Pressure Registry. Their analysis included 63,910 adults recruited to the registry during 2004-2014.
Patients had blood pressure measurements taken in the clinic according to standard procedures. Afterward, they had ambulatory blood pressure monitoring that used an automated device programmed to record BP every 20 minutes during the day and every 30 minutes at night.
They found that overall clinic and ambulatory blood pressure measurements had a relatively similar magnitude of association with all-cause and cardiovascular mortality.
However, clinic systolic pressure lost its predictive power for all-cause mortality after adjustment for 24-hour ambulatory systolic pressure. The hazard ratio for all-cause mortality dropped from 1.54 before the adjustment to 1.02 after the adjustment, Dr. Banegas and his colleagues reported.