AB0311 HEMOSTASIS IN AFRICAN BLACK COMPARED TO WHITE PATIENTS WITH RHEUMATOID ARTHRITIS
Authors: Chanel Robinson, Linda Tsang, Ahmed Solomon, Angela Woodiwiss, Gavin Norton, Hon-Chun Hsu, Mervyn Mer, Aletta Millen, Patrick Dessein
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Aberrant hemostasis is implicated in the increased CVD risk experienced by patients with rheumatoid arthritis (RA) (1). Large circulating concentrations of plasminogen activator inhibitor-1 (PAI-1) predict cardiovascular event rates (2). PAI-1 levels are markedly smaller in American and African black populations than in those of European descent (3,4). Whether this protection persists in black persons who have RA is unknown. <h3>Objectives</h3> This study compared hemostasis factors among African black and white RA patients <h3>Methods</h3> PAI-1, tissue factor pathway inhibitor (TFPI) and tissue plasminogen activator (t-PA) levels were measured by ELISA in 236 (114 black; 122 white) African RA patients. Data were analysed in mixed regression models. <h3>Results</h3> In age and sex adjusted analysis, PAI-1 concentrations were larger in black compared to white patients with RA (median (interquartile range (IQR))=12.4 (3.1-28.7) versus 5.4 (1.5-25.0) ng/ml, p=0.006). In all patients, body mass index (BMI) (β (SE)=0.022 (0.007), p=0003), waist circumference (β (SE)=0.007 (0.003), p=0.04) and tetracycline use (β (SE)=0.291 (0.133), p=0.03) were associated with logarithmically transformed PAI-1 levels. Population grouping did not influence these relationships (interaction p&gt;/=0.8) but impacted rheumatoid factor (RF) positivity- and azathioprine use-PAI-1 level associations (interaction p=0.03 and 0.004, respectively). In stratified analysis, RF positivity was associated with PAI-1 levels in white (β (SE)=0.344 (0.139), p=0.01) but not black patients (β (SE)=-0.102 (0.143), p=0.5), and azathioprine use was associated with PAI-1 levels in black (β=0.400 (0.155), p=0.01) but not white patients (β (SE)=0.305 (0.184), p=0.1). In age, sex, BMI, RF positivity and azathioprine and tetracycline use adjusted analysis, black population origin remained associated with PAI-1 levels (β (SE)=0.175 (0.091), p=0.05). In age and sex adjusted analysis, TFPI and t-PA levels did not differ in black compared to white RA patients (median (IQR)=221.0 (149.8-410.5) versus 225.0 (130.4-357.2) pg/ml, p=0.6, and 6.7 (4.9-9.1) versus 7.4 (4.4-10.0) pg/ml, p=0.3). <h3>Conclusion</h3> PAI-1 concentrations are substantially larger in African black compared to white patients with RA. <h3>References</h3> [1] Van den Hoever IAM, Sattar N, Nurmohamed MT. Thromboembolic and cardiovascular risk in rheumatoid arthritis: role of the haemostatic system. Ann Rheum Dis 2014;73:954-7. [2] Jung RG, Motazedian P, Ramirez FD, et al. Association between plasminogen activator-1 and cardiovascular events: a systematic review and meta-analysis. Thrombosis J (2018) 16:12. [3] Festa A, D'Agostino R, Rich SS, et al. Promoter (4G/5G) plasminogen activator inhibitor-1 genotype and plasminogen activator inhibitor-1 levels in blacks, Hispanics and non-Hispanic whites. The Insulin Resistance Atherosclerosis Study. Circulation 2003;107:2422-7. [4] De Lange Z, Rijken DC, Hoekstra T, et al. In black South Africans from rural and urban communities, the 4G/5G PAI-1 polymorphism influences PAI-1 activity, but not plasma clot lysis time. PLoS One 2013;8 (12): e83151. <h3>Disclosure of Interests</h3> None declared