By Eleanor McDermid, Senior medwireNews Reporter
Calculating blood pressure (BP) load does not increase physicians’ ability to predict a patient’s risk of cardiovascular events, research shows.
Although related to cardiovascular risk, the measure did not significantly improve risk prediction based on ambulatory BP, even in people with normal BP in whom BP load was hypothesised to be particularly useful.
A cross-sectional study recently reported by medwireNews showed that BP load was not associated with target-organ damage. The latest research, which appears in Hypertension, shows that this also applies to clinical events in prospectively monitored patients.
In a related editorial, Gianpaolo Reboldi (University of Perugia, Italy) and colleagues advise physicians to stick to measures with proven benefit. “From an operational standpoint [...] mean ambulatory BP should remain the first-line procedure to identify subjects needing antihypertensive drug treatment.
“In addition, a nondipping pattern, an elevated 24-hour pulse pressure, as well as an increased night-time systolic BP variability are independent markers of added cardiovascular risk.”
The study involved 11,785 participants, from 11 population studies in Europe, Asia and South America, who were included in the International Database on Ambulatory blood pressure in relation to Cardiovascular Outcomes (IDACO).
The participants’ BP, likelihood of being hypertensive, and having diabetes or a baseline cardiovascular disorder rose with increasing quartiles of BP load. Also, both BP level and BP load significantly predicted cardiovascular outcomes during a median 10.7 years of follow-up, during which time there was a total of 1109 events. The risk of all fatal and nonfatal cardiovascular events increased by 14%, 10% and 15% per decile increase in BP level, load as a percentage and load as an area under the curve, respectively.
However, BP load did not aid risk stratification; when added to a multivariate model that included 24-hour systolic and diastolic BP, increased BP load was not significantly associated with any outcome. This was despite the researchers defining increased BP load as the threshold above which it was associated with more cardiovascular events than was a BP level of 130/80 mmHg or higher.
The findings were similar when restricted to 4825 untreated participants with normal ambulatory BP levels, about 16% of whom had an increased BP load.
“From a clinical point of view, our results suggest that there is no need to compute complex statistics such as area under the curve when a simple arithmetic average provides the similar prognostic information,” conclude Jan Staessen (University of Leuven, Belgium) and colleagues.
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