aDepartment of Radiology, University of Washington Medical Centre, Seattle, Washington, USA bNational Heart & Lung Institute, Imperial College London cDepartment of Radiology, St Mary's Hospital, Imperial College NHS Healthcare Trust, London, UK.
Stroke is elevated in people of black African descent, but evidence for excess subclinical cerebrovascular disease is conflicting, and the role of risk factors in determining any ethnic differences observed unexplored.
We compared prevalence of brain infarcts, and severe white matter hyperintensities (WMHs) on cerebral MRI, in a community-based sample of men and women aged 58-86 of African Caribbean (214) and European (605) descent, in London, UK. Resting, central and ambulatory blood pressure (BP) were measured; diabetes was assessed by blood testing and questionnaire.
Mean age was 70. Multiple (≥4) brain infarcts and severe WMH occurred more frequently in African Caribbeans (18/43%), than Europeans (7/33%, P=0.05/0.008). Separately, clinic and night-time ambulatory BP were significantly associated with severe WMH in both ethnic groups; when both were entered into the model, the association for clinic SBP was attenuated and lost statistical significance [1.00 (0.98-1.02) P=0.9 in Europeans, 1.00 (0.97-1.04) P=0.9 in African Caribbeans], whereas the association for night-time SBP was retained [1.04 (1.02-1.07) P<0.001 in Europeans, 1.08 (1.03-1.12), P=0.001 in African Caribbeans]. The greater age-adjusted and sex-adjusted risk of severe WMH in African Caribbeans compared with Europeans [2.08 (1.15-3.76) P=0.02], was attenuated to 1.45 [(0.74-2.83) P=0.3] on adjustment for clinic and night-time systolic pressure, antihypertensive medication use and glycated haemoglobin.
African Caribbeans have a greater burden of subclinical cerebrovascular disease than Europeans. This excess is related to elevated clinic and ambulatory BP, and to hyperglycaemia.