Background Rheumatoid arthritis (RA) is characterized by inflamed joint derived cytokine mediated high-grade systemic inflammation that enhances cardiovascular metabolic risk and disease in developed populations.
Objectives We investigated the potential impact of RA on cardiovascular risk factors including systemic inflammation, atherosclerosis and their relationships in black Africans from a developing population.
Methods We evaluated demographic features, adiposity indices, major traditional cardiovascular risk factors, circulating C-reactive protein and interleukin-6 concentrations and ultrasound determined carotid intima-media thickness (cIMT) in 274 black Africans; 115 had established RA. Data were analyzed in confounder adjusted mixed regression models.
Results The body mass index and waist-height ratio were lower in RA compared to non-RA subjects (29.2 (6.6) versus 33.7 (8.0), P<0.0001 and 0.58 (0.09) versus 0.62 (0.1), P=0.0003, respectively). Dyslipidemia was less prevalent in patients with RA (odds ratio (OR) (95% confidence interval (CI)=0.54 (0.30 to1.00)); this disparity was no longer significant after further adjustment for reduced adiposity and chloroquine use. RA was also not associated with hypertension, current smoking and diabetes. The number of major traditional risk factors did not differ by RA status (1.1(0.8) versus 1.2(0.9), P=0.7). Circulating C-reactive protein concentrations were similar and serum interleukin-6 concentrations reduced in RA (7.2 (3.1) versus 6.7 (3.1) mg/l, P=0.7 and 3.9 (1.9) versus 6.3 (1.9) pg/ml, P<0.0001, respectively). The cIMT was 0.700 (0.085) and 0.701 (0.111) mm in RA and non-RA subjects, respectively (P=0.7). RA disease activity and severity parameters were consistently unrelated to systemic inflammation, despite the presence of clinically active disease in 82.6% of patients. In all participants, adiposity indices, smoking and converting angiotensin inhibitor non-use were associated with increased systemic inflammation, which related to more atherogenic lipid profiles, and circulating low density lipoprotein concentrations were associated with cIMT (partial R=0.153, P=0.032); RA did not impact on these relationships (interaction P>0.1).
Conclusions Among black Africans, patients with established RA experience reduced overall and abdominal adiposity but no enhanced major traditional risk factor and atherosclerosis burden. This study further suggests that an absent interleukin-6 release by inflamed RA joints into the circulation may account for this unaltered cardiovascular disease risk.
Acknowledgements This study was supported by a South African Medical Research Council grant and the National Research Foundation.
Disclosure of Interest None Declared
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