Carotid intima-media thickness and cardiovascular disease risk in African populations

Chapter 2 determined the association of the classical cardiovascular risk factors and HIV with CIMT. Participants from Ghana and Burkina Faso had higher CIMT compared with other sites. Age (β = 6.77, 95%CI [6.34, 7.19] µm), body mass index (17.6 [12.5, 22.8] µm), systolic blood pressure (7.52 [6.21, 8.83] µm), low-density lipoprotein cholesterol (5.08 [2.10, 8.06] µm) and male gender (10.3 [4.75, 15.9] µm) were associated with higher CIMT. Smoking was associated with higher CIMT in men. High-density lipoprotein cholesterol (-12.2 [-17.9, -6.41] µm) and alcohol consumption (–13.5 [-19.1, -7.91] µm) were inversely associated with CIMT. CVD may become a major pan-African epidemic unless hypertension, obesity, and smoking are controlled. In response to the rising prevalence of obesity in SSA, chapter 3 determined the association between various adiposity phenotypes and CIMT in middle aged adults from SSA. In pooled analyses, BMI (β–value [95% CIs]: 19.5 [16.8, 22.3] µm) showed the strongest relationship with CIMT followed by VAT (5.86 [4.65, 7.07] µm), SCAT (5.00 [2.85, 7.15] µm), WC (1.27 [1.09, 1.44] µm) and HC (1.23 [1.04, 1.42] µm). Obesity within SSA will likely result in higher levels of atherosclerosis and cardiovascular events, especially in males. Chapter 4 is an individual participant data meta-analysis examining race-ethnic differences in the association of classical cardiovascular risk factors with CIMT. 34,025 individuals from African, African American, Asian, European and Hispanic populations were studied. Age, sex, body mass index (BMI) and systolic blood pressure (SBP) had a significant positive association with CIMT in all ethnicities at varying magnitudes. When compared to European populations, smoking (beta coefficient [95% CI]: 0.39mm [0.09, 0.70]), BMI (0.05mm [0.01, 0.08]) and glucose (0.13mm [0.06, 0.19]) had the strongest positive association with CIMT in the Asian population. High density lipoprotein-cholesterol (HDL-C) had significant protective effects in African American (-0.31mm [-0.42, -0.21]) and African (-0.26mm [-0.31, -0.19]) populations only. Primary prevention strategies and aetiology of CVD differ across race-ethnicities. Chapter 5 expands the evidence on the utility of the cardiovascular health index (CVHI), a valid, accessible, simple, and translatable metric for monitoring cardiovascular health using seven ‘life’s simple 7’ CVD risk: smoking, dietary intake, physical activity, body mass index, blood pressure, glucose, and total cholesterol. We observed inverse associations between CVHI and common CIMT (β-coefficients [95% confidence interval]: Burkina Faso, − 6.51 [− 9.83, − 3.20] μm; Ghana, − 5.42 [− 8.90, − 1.95] μm; Kenya, − 6.58 [− 9.05, − 4.10] μm; and South Africa, − 7.85 [− 9.65, − 6.05] μm). Inverse relations were observed for women (− 4.44 [− 6.23, − 2.65] μm) and men (− 6.27 [− 7.91, − 4.64] μm) in the pooled sample. Smoking (p < 0.001), physical activity (p < 0.001), and hyperglycemia (p < 0.001) were related to CIMT in women only, while blood pressure and obesity were related to CIMT in both women and men (p < 0.001). Primary prevention of CVD should target physical activity, smoking, obesity, hypertension, and hyperglycemia. In chapter 6, association of microalbuminuria with CIMT and of both these variables with 10-year predicted ASCVD are reported. High CIMT and microalbuinurai were each associated with older age and high prevalence of both diabetes and hypertension. The urine albuminuria was associated with higher odds of carotid atherosclerosis compared to albumin-creatinine-ratio. Common CIMT and microabuminuria were strongly associated with 10-year ASCVD risk. Urine albuminuria was associated with (odds ratio, 1.27 95% confidence interval [1.12, 1.43] 10-year ASCVD risk in both women an men. Urine albumin can be used as a marker of CVD risk in population screening studies.