An international matched cohort study of the contribution of metabolic impairments to subclinical atherosclerosis in United Kingdom and Jamaican African-Caribbeans.
BACKGROUND
A gradient of increased vascular risk exists across the African diaspora. We hypothesised that increased insulin resistance with environmental transition contributes to this risk.


METHODS
The study was undertaken in 73 healthy African-Caribbeans in the UK and 151 age and sex matched African-Caribbeans in Jamaica. Body mass index (BMI), fasting insulin, insulin resistance, carotid intima media thickness (CIMT) and endothelium dependent vasodilatation (EDV) were compared. CIMT was measured ultrasonographically in the distal 1cm of both common carotid arteries. EDV was measured the absolute change from baseline in the Reflection index (RI) of the digital volume pulse during intravenous infusion of albuterol (DeltaRI(ALB)).


RESULTS
UK African-Caribbeans had greater CIMT (mean difference 0.124 [95% C.I. 0.075-0.173] mm, p<0.0001) and decreased EDV (mean difference in DeltaRI(ALB) 5.1 [95% C.I. 2.5-7.6] percentage points, p<0.0001). This was associated with higher insulin concentrations (mean difference 1.6 [95% C.I. 1.3-4.1] microU/mL, p=0.038) and greater HOMA score (2.8 versus 2.0; p=0.035) despite no significant differences in BMI (28.8 versus 27.6; p=0.168) or the waist to hip ratio (0.86 versus 0.85; p=0.188). HOMA scores correlated positively with CIMT (r=0.35, p=0.01) and negatively with DeltaRI(ALB) (r=-0.17; p=0.02) in UK, but not in Jamaican, African-Caribbeans. A significant interaction was seen between HOMA and UK domicile for CIMT (p<0.0001) and between fasting insulin and UK domicile for DeltaRI(ALB) (p<0.0001).


CONCLUSIONS
Increased insulin resistance, associated with living in a nutritionally enriched environment, may contribute to early subclinical atherosclerosis in UK African-Caribbeans.
Cardiovascular Division, King's College London School of Medicine, London, UK. lalit.kalra@kcl.ac.uk
Lalit
L
Kalra
Elizabeth
E
Iveson
Curtis
C
Rambaran
Roy
R
Sherwood
Philip
P
Chowienczyk
James
J
Ritter
Ajay
A
Shah
Terrence
T
Forrester
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage; D044383:Black People / Q000706:statistics & numerical data*; D015992:Body Mass Index; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000276:immunology / Q000378:metabolism; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000208:ethnology* / Q000378:metabolism*; D015331:Cohort Studies; D004777:Environment; D005260:Female; D015438:Health Behavior; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D007563:Jamaica / Q000453:epidemiology / Q000208:ethnology; D008019:Life Style; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000276:immunology / Q000378:metabolism; D014463:Ultrasonography; D006113:United Kingdom / Q000453:epidemiology; D014657:Vasculitis / Q000000981:diagnostic imaging / Q000208:ethnology / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D007328:Insulin; D000420:Albuterol