The largest study ever conducted of ambulatory blood pressure (BP) monitoring (ABPM) has shown that measuring BP over a 24-hour period predicts all-cause and cardiovascular mortality much better than do office or clinic measurements. "Our study suggests that more frequent use of 24-hour blood pressure measurement could improve the diagnosis and management of hypertension, which is the primary cause of premature death and disability worldwide," lead author, José Ramon Banegas. The study was published in The New England Journal of Medicine (NEJM).

The study also showed that masked hypertension, where BP is standard in the clinic but elevated out of the office, was linked to the highest risk for mortality but would never be identified by just measuring BP at the clinic. White coat hypertension, where BP is elevated in the clinic but not outside, was also associated with high risks.

"A hypertension diagnosis based exclusively on blood pressure readings in the clinic is no longer acceptable. There is no scientific or clinic justification for not using ABPM, which should be part of the evaluation and follow-up of most hypertensive patients," Banegas said. The researchers analyzed data from a registry of 63,910 adults recruited from Spanish primary care centres between 2004 and 2014.

Patients were required to meet guideline-recommended indications for ABPM, which included suspected white coat hypertension, refractory or resistant hypertension, high-risk hypertension, and labile or borderline hypertension, as well as an assessment of drug-treatment efficacy and study of the circadian BP pattern. They had their BP measured in the clinic and again over 24 hours using ABPM devices.

During a median follow-up of 4.7 years, 3808 patients died of any cause, and 1295 of these patients died of cardiovascular causes.  Results showed that 24-hour systolic BP was more strongly associated with all-cause mortality than the clinic systolic BP (HR, 1.02). Nighttime-alone and daytime-alone measurements had risks very similar to those of 24-hour BP.

The other major finding was that masked hypertension had the highest risk of all, he added. "In our dataset, masked hypertension was present in 4% of the population studied, and when we add in masked uncontrolled hypertension, this rises to almost 10%. The study provides the most compelling evidence yet that there should be wider use of ABPM to confirm the diagnosis of hypertension and monitor the quality of blood pressure control.

Gild for the Lily

"The take-home message from this study is that ambulatory blood-pressure monitoring is a valuable tool in the assessment of the most important and treatable factor worldwide contributing to premature death and disability, namely blood pressure," he writes.

The Author hoped that the work would serve as one more spur to manufacturers of ambulatory blood-pressure monitoring devices and providers in this field to initiate a registry in the United States. ABPM is becoming more accepted in Spain, and now with the current publication, he is hoping it will be used more frequently worldwide.