Interarm BP difference leads to reduced survival
MedWire News: According to researchers writing in the British Medical Journal, patients with hypertension who have different blood pressure (BP) measurements in each arm have a reduced chance of survival over 10 years.
Christopher Clark (University of Exeter, UK) and co-authors say that national guidelines advising doctors to measure BP in both arms of patients are routinely not being followed.
They point out that "this study supports the potential value of an interarm difference as a simple clinical indicator of increased cardiovascular risk," and state that it should become a core component of BP measurement in primary care.
The study involved 230 individuals who received treatment for hypertension in primary care. Hypertension was defined by the then current guidelines of the British Hypertension Society (≥160/100 mmHg or ≥140/90 mmHg in the presence of target organ damage, diabetes or coronary heart disease risk score ≥15%).
At recruitment, 55 (24%) participants had a mean interarm difference in systolic BP (SBP) of 10 mmHg or more, and 21 (9%) had an SBP difference of 15 mmHg or more.
These interarm differences were associated with a 3.6- and 3.1-fold increased risk for all-cause mortality, respectively, corresponding to a 5-6% increase in the risk for adverse outcomes for each 1-mmHg increment in interarm difference for SBP.
An interarm difference in diastolic BP (DBP) of 10 mmHg or more was associated with an increased risk for cardiovascular events and combined nonfatal events or all-cause mortality in nonadjusted (hazard ratio [HR]=3.8) and adjusted analyses (HR=3.3).
After adjustment, this corresponded to a 9% increase in the risk for any fatal or nonfatal event for each 1-mmHg increment in interarm difference for DBP.
Further analysis showed that patients who had an interarm difference in SBP of 10 mmHg or more without pre-existing disease and a cardiovascular risk score of more than 20% had a significantly higher risk for combined fatal and nonfatal events than those who had an interarm difference in SBP of less than 10 mmHg and an equivalent risk score (p<0.001).
These individuals also had a higher risk for combined fatal and nonfatal events than those with pre-existing disease (p<0.05). "This would suggest that those with an interarm difference may justifiably require aggressive management along secondary prevention guidelines," write the authors.
They say that measuring interarm BP difference has the potential to act as a simple noninvasive test that could identify those who could benefit from more intensive assessment.
In an accompanying editorial, Dae Kim (Harvard Medical School, Boston, Massachusetts, USA) says that in patients who have an interarm BP difference, subsequent monitoring should be performed in the arm with the higher reading, as this will help to determine the necessary treatment.
"Further studies of the association of interarm differences in BP with other manifestations of peripheral and cardiovascular disease, in cohorts representative of the primary care population, would be valuable," the authors conclude.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012
By Piriya Mahendra