Blood pressure has heterogeneous associations with cardiovascular diseases

Jun 5 2014

By Eleanor McDermid, Senior medwireNews Reporter

The associations between blood pressure (BP) and cardiovascular disease (CVD) are variable, reveals a large study that highlights the impact of angina and heart failure.

The findings show that, overall, a 30-year-old person with hypertension had a 63.3% lifetime risk of CVD, compared with a 46.1% risk for a person with normal BP, and developed CVD 5.0 years earlier.

However, the largest proportion (43%) of these 5.0 years were accounted for by stable and unstable angina. For an 80-year old with hypertension, heart failure and stable angina were the predominant forms of CVD, each accounting for 19% of a total 1.6 CVD-free years lost.

“Our estimates of lifetime risks and years of cardiovascular disease-free life lost to different diseases can be used to extend the existing counselling of patients and decision making, which is based on heart attack and stroke risks alone”, say lead researcher Eleni Rapsomaniki (The Farr Institute of Health Informatics Research, London, UK) and colleagues.

“Here, we show the importance of other diseases that might be more common”, they write in The Lancet.

The findings are based on data for 1.25 million patients registered with UK primary care practices who were aged at least 30 years old and were free of CVD at baseline. Over a median 5.2 years of follow-up, the patients had 83,098 CV events.

The researchers found the lowest CVD risk among patients with systolic BP between 90 and 114 mmHg and diastolic BP between 60 and 74 mmHg, regardless of the specific CVD outcome. There was no evidence of a J-shaped association (ie, increased risk at very low BP).

However, the risk conferred by high BP varied according to the specific form of CVD. The effect of a 20 mmHg rise in systolic BP ranged from 44%, 43% and 41% increases in the risk of intracerebral haemorrhage, subarachnoid haemorrhage and stable angina, respectively, down to a nonsignificant 8% increase in the risk of abdominal aortic aneurysm.

By contrast, each 10 mmHg rise in diastolic BP was associated with a 45% rise in the risk of abdominal aortic aneurysm, as well as 50% and 42% increases in the risk of intracerebral haemorrhage and subarachnoid haemorrhage, respectively. But the rise in stable angina risk was lower, at 28%.

On the whole, the effect of BP on each form of CVD lessened with increasing age, except that the effect of diastolic BP on abdominal aortic aneurysm risk was highest in people older than 80 years.

In an accompanying commentary, Thomas Kahan (Karolinska Institutet, Sweden) notes that the data provide “circumstantial support” for treating mild hypertension in young people, as well as for controlling BP in octogenarians.

But he adds that more efforts are needed to identify and control BP across the board. “The clinical benefit of improved risk assessment and appropriate treatment might be substantial”, he says.

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