Inter-arm blood pressure difference, when is it a useful risk marker for cardiovascular events?

Differences in the blood pressure between arms (inter-arm difference; IAD) are regularly encountered in assessing people with hypertension. A pooled analysis of community-based studies found systolic IADs ≥10 mmHg in 11.2% of people with hypertension, 7.4% with diabetes and 3.6% of a general adult population [ 1 ]. A systolic IAD ≥ 10 mmHg is associated with increased cardiovascular and all-cause mortality, and with cardiovascular events. We have recently confirmed this in an individual participant data (IPD) meta-analysis using 10 years of follow up data from over 50,000 participants pooled from 24 cohorts to establish the INTERPRESS-IPD Collaboration. We derived and validated prediction models which included systolic IAD as a risk marker, and confirmed the association of IAD with elevated risk after adjustment for frequently used cardiovascular risk prediction scores (ASCVD, Framingham and QRISK2) [ 2 ]. This work was designed to support interpretation of an IAD to stratify risk and inform management decisions within a primary care population.