Prospective study of cardiovascular disease and Its risk factors in populations with rheumatoid arthritis that are at different stages of the epidemiological transition

Abstract

Rheumatoid arthritis (RA) increases the risk of particularly atherosclerotic cardiovascular disease in developed populations. The sub-Saharan black African population is currently at an earlier epidemiological health transition stage. Consequently, black Africans experience a markedly reduced risk of atherosclerotic cardiovascular disease. The main objectives of this thesis were to determine whether (1) the atherosclerotic cardiovascular risk burden is reduced in black compared to other African patients with RA; (2) RA impacts on cardiovascular risk factor profiles and ultrasound determined carotid intima-media thickness among black Africans and (3) the atherosclerosis burden and its association with traditional and non-traditional risk factors differ in black compared to white Africans with RA. Black compared to other Africans with RA had more prevalent hypertension and obesity but smoked and consumed alcohol less frequently. However, the overall traditional and nontraditional atherosclerotic cardiovascular risk burden was as large in black as in other Africans with RA. RA was not independently associated with unfavourable traditional and non-traditional atherosclerotic risk factors including systemic inflammation among black Africans. Carotid intima-media thickness was similar in black RA and non-RA Africans. The carotid intima-media thickness and plaque prevalence were as large in black compared to white African patients with RA. Blood pressure, dyslipidemia, Framingham score, systemic inflammation and extraarticular manifestations were associated with atherosclerosis in white but not black African RA patients. The Arthritis Impact

Measurement Scales tension score was consistently related to atherosclerosis in black but not white African patients with RA. Black African RA women experienced a markedly larger adiposity burden than their white counterparts. However, body mass index was associated with carotid intima-media thickness and waist-to-hip ratio with plaque in white but not black women with RA. The US National Cholesterol Education Program Adult Treatment Panel III metabolic syndrome was identified in 30.8% of black compared to 9.7% of white African women with RA (p = 0.009). In white African RA women, the metabolic syndrome definition was associated with carotid intima-media thickness and the triglyceride criterion and number of metabolic syndrome criteria were associated with plaque. In black African RA women, only the blood pressure criterion was associated with carotid intima-media thickness, which represents mostly age and blood pressure induced hypertrophy of medial cells rather than atherosclerosis. Reduced estimated glomerular filtration rate was found in 49.1% of black compared 30.6% of white African patients with RA (p=0.004). In Receiver Operating Characteristic curve analysis, eight of nine evaluated estimated glomerular filtration rate equations were associated with carotid artery plaque to a clinically useful extent for cardiovascular risk stratification in black but not white African patients with RA. By contrast, estimated glomerular filtration rate was related to the endothelial activation markers of monocyte chemoattractant protein-1 and angiopoietin 2 in white but not black African patients with RA. In conclusion, the overall cardiovascular risk factor and atherosclerosis burden are currently as large in black compared to white African patients with RA. Modifiable traditional risk factors and disease characteristics were consistently unrelated to atherosclerosis in black

African patients with RA. Impaired kidney function comprised the only routinely available cardiovascular risk factor that was useful in identifying black African RA patients with high risk atherosclerosis.Systematic vascular imaging and possibly the use of novel cardiovascular risk biomarkers may be required for adequate cardiovascular risk stratification among black African patients with RA.