Age confounds relationship between ambulatory and office BP

Sep 17 2014

By Eleanor McDermid, Senior medwireNews Reporter

The relationship between ambulatory and office blood pressure (BP) varies with age, with the likelihood of white-coat hypertension increasing as people get older, a study shows.

Conversely, masked hypertension was much more common among younger patients, especially in men, report David Conen (University Hospital Basel, Switzerland) and study co-authors.

In an editorial accompanying the study in Hypertension, George Stergiou (Sotiria Hospital, Athens, Greece) observes that, although not a new finding, this association “is largely neglected and ignored and has major clinical implications.”

The study data, on 9550 participants who were at least 18 years old and not taking antihypertensives, came from the International Database on Ambulatory blood pressure in relation to Cardiovascular Outcomes (IDACO) and the Genetic and Phenotypic Determinants of Blood Pressure and Other Cardiovascular Risk Factors (GAPP) study.

Office BP and ambulatory BP both rose with older age, but office BP rose faster. Among men, for example, office systolic BP rose from 123.5 mmHg in 18–30-year olds to 150.8 mmHg in those age 70 years or more, while the corresponding values for ambulatory BP were 128.3 and 136.7 mmHg. There was a similar pattern in women.

Thus, younger people had higher ambulatory than office BP and were likely to have masked hypertension, whereas older people had higher office BP and an increased likelihood of white-coat hypertension.

Among women, the rate of white-coat hypertension increased with age, but the rate of masked hypertension remained relatively stable. Sustained hypertension became more common with age in both genders.

In men, the prevalence of white-coat hypertension rose from 3.6% in 18–30-year olds to 18.5% in those aged 70 years or more. The corresponding rates of masked hypertension among men were 18.2% and 10.2%; however, it was most common between the ages of 30 and 50 years, at around 27%.

Conen et al therefore suggest that, if the prognostic effect of masked hypertension proves equally strong at all ages, physicians should make a point of measuring ambulatory BP in middle-aged men.

In his editorial, Stergiou says that conflicting BP measurements are “inevitable” when using multiple methods “and getting around this problem is a challenge.”

But given that ambulatory BP is more closely linked to cardiovascular outcomes than is office BP, he suggests that office BP should be used for widespread screening, but if ambulatory BP is available then this alone should guide therapeutic decisions.

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