Inter-arm systolic blood pressure differences, relations with future vascular events and mortality in patients with and without manifest vascular disease

Background Inter-arm systolic blood pressure difference (SBPD) is an easily obtained patient characteristic which relates to vascular disease. We aimed to identify determinants of large inter-arm SBPD and to investigate the relation between inter-arm SBPD and vascular events in patients with and without manifest vascular disease. Methods In a cohort of 7344 patients with manifest vascular disease or vascular risk factors alone enrolled in the Second Manifestations of ARTerial disease (SMART) study, single bilateral non-simultaneous blood pressure measurements were performed. Logistic and Cox regression was used to identify determinants of large inter-arm SBPD (≥ 15 mm Hg) and to investigate the relation between inter-arm SBPD and vascular events (composite of non-fatal myocardial infarction, stroke, and vascular mortality) and all-cause mortality. Results In all patients the median inter-arm SBPD was 7 mm Hg (IQR 3–11) and 1182 (16%) patients had inter-arm SBPD ≥ 15 mm Hg. Higher age, higher systolic blood pressure, diabetes mellitus, peripheral artery disease, carotid artery stenosis, higher carotid intima-media thickness, and lower ankle-brachial indices were related to large inter-arm SBPD (≥ 15 mm Hg). Each 5 mm Hg increase in inter-arm SBPD was related to a 12% higher risk of vascular events in patients without manifest vascular disease (HR 1.12; 95% CI 1.00–1.27), whereas no relation was apparent in patients with manifest vascular disease (HR 0.98; 95% CI 0.93–1.04, interaction p-value 0.036). Inter-arm SBPD was not related to all-cause mortality (HR 1.05; 95% CI 0.93–1.19). Conclusions Inter-arm SBPD relates to a higher risk of vascular events in patients without manifest vascular disease, whereas this relation is not apparent in patients with manifest vascular disease.