Increased variability in blood pressure (BP) may be an indicator of overall cardiovascular (CV) risk rather than being a risk factor per se, suggest researchers.
Jacques Blacher (Hôtel-Dieu Hospital, Paris, France) and colleagues found that adding BP variability to a baseline risk model resulted in a slight, nonsignificant improvement in the ability to discriminate between people who did and did not have a CV event.
However, they stress that the predictive ability of the baseline model was low, with an accuracy of 63.8%, “stressing the importance of improving prediction.” The addition of BP variability increased accuracy to 64.3%.
Also, the team notes that the findings only apply to high-risk patients. The 2157 patients in the study had experienced a cerebral or coronary ischaemic event during the year prior to inclusion, had risk factors such as diabetes or current/former smoking, and a large proportion were hypertensive or were taking antihypertensive medications. During follow-up lasting a median of 4.7 years, the patients had 110 CV events (nonfatal myocardial infarction or ischaemic stroke, or CV death).
BP variability in these patients was associated with CV risk factors including age, hypertension, hypercholesterolaemia and Type 2 diabetes, with age, Type 2 diabetes and systolic BP remaining significant on multivariate analysis.
“This may not be surprising as CV risk factors are associated with a derangement of mechanisms subserving BP homeostasis as well with large and small artery structural damage that amplifies BP changes in response to environmental or endogenous stimuli”, write the researchers in the Journal of Human Hypertension.
When divided into tertiles of BP variability, the cumulative survival free of CV events decreased with increasing tertile; however, the differences between the tertiles were not significant. Nevertheless, each standard deviation increase in BP variability in multivariate analysis was associated with a significant 1.23-fold increase in risk of a CV event. Also, recent cerebrovascular rather than coronary event increased the risk a significant 1.92-fold and tobacco use increased it 1.94-fold.
Overall, the strong association between BP variability and CV risk factors and its weak added value in terms of prognosis lead the researchers to suggest that it acts “more as an integrator of other risk factors than as a robust independent CV risk factor.”
BP variability may be ‘CV risk integrator’
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