Ambulatory blood pressure risk is age dependent

By Eleanor McDermid, Senior medwireNews Reporter

The risk associated with raised ambulatory blood pressure (BP) is modified by a patient’s age, research shows.

Below the age of 50 years, diastolic (D)BP had the strongest association with cardiovascular risk, whereas systolic (S)BP was the main driver of events in older people, report Jan Staessen (University of Leuven, Belgium) and co-workers.

“Our findings [argue] against the suggestion to abandon diastolic pressure measurement and to rely only on systolic blood pressure for the management of hypertension”, write the researchers in Circulation.

The study cohort included 8341 individuals from the International Database on Ambulatory blood pressure in relation to Cardiovascular Outcomes (IDACO) who were at least 18 years old, had sufficient ambulatory BP measurements and were not taking antihypertensive medications at baseline. In all, 4.9% of these participants had isolated diastolic hypertension on 24-hour ambulatory blood pressure measurement, and the rate rose to 17.2% among participants with ambulatory hypertension.

The team also notes research showing cardiovascular risk reduction associated with antihypertensive treatment in patients with isolated diastolic hypertension, which “confirms that certainly in younger individuals diastolic blood pressure is a risk factor that must be treated.”

Participants with isolated diastolic hypertension were more often men who drank alcohol and had a higher body mass index and a worse lipid profile, relative to those with normal BP.

During a median follow-up of 11.2 years, 927 participants died (including 356 cardiovascular deaths) and 744 had a fatal or nonfatal cardiovascular event. After accounting for confounders, increasing 24-hour DBP significantly increased the risk of these outcomes among patients younger than 50 years. Each standard deviation increase raised the risk of total mortality 2.05-fold, cardiovascular mortality 4.07-fold and cardiovascular events 1.74-fold. Increasing 24-hour SBP, however, was not predictive in this age group.

By contrast, in older participants each standard deviation increase in SBP raised the risk of total mortality, cardiovascular mortality and cardiovascular events 1.19-, 1.51- and 1.39-fold, respectively, whereas DBP was not associated with these endpoints.

The effect of SBP and DBP on cardiovascular risk was similar in Asians and Caucasians, but the effect of SBP was stronger in women than men for most outcomes. Finally, the team shows that the effect of SBP on 10-year cardiovascular risk was independent of DBP, and vice versa.

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