Inter-arm blood pressure difference and its relationship with retinal microvascular calibres in young individuals: the African-PREDICT study

Abstract

Background Bilateral systolic blood pressure (SBP) differences > 10 mmHg is a common finding in clinical practice. Such BP differences in older individuals are associated with peripheral vascular disease, linked to microvascular dysfunction. Investigating retinal vessel calibres could provide insight into systemic microvascular function and may predict cardiovascular outcomes. Therefore we investigated the link between inter-arm systolic blood pressure differences (IASBPD) and the retinal microvasculature to determine the usefulness of IASBPD as an early marker of microvascular changes. Methods In this cross-sectional study, we used data from 403 apparently healthy participants (20-30 years) (42% men; 49% black) taking part in the African-PREDICT study. Participants underwent retinal vessel imaging, anthropometric measurements and blood sampling. Brachial BP was measured sequentially in both arms to determine the mean IASBPD. Results Participants were stratified into two groups with an IASBPD < 10 mmHg (n=329) and ≥ 10 mmHg (n=47), the only difference in characteristics being a higher right arm SBP in the latter group (p=0.005). We found no association between IASBPD and retinal vessel calibres in any group. Less than 2% of the variance in IASBPD was explained by potential risk factors, with only SBP associating independently with IASBPD (β=115; p=0.039). Conclusion In a young population an increased IASBPD is not related to retinal vessel diameters suggesting that it does not reflect early microvascular alterations