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Quality of and predictors of anticoagulation control among multi ethnic cohorts receiving vka therapy for stroke prevention in atrial fibrillation

Introduction: To ensure the effectiveness and safety of vitamin K anatomist (VKA) therapy among atrial fibrillation (AF) patients, the International Normalised Ratio (INR) should be 2.0-3.0. Although epidemiological studies suggest poorer INR control in non-white cohorts, anticoagulation control comparing different ethnic groups has not been well-investigated.

Objective: To investigate the quality of VKA control and predictors of anticoagulation control in AF patients in a multi-ethnic cohort managed by one hospital-based anticoagulant clinic.

Methods: Retrospective assessment of the quality of VKA control by the time in therapeutic range, (TTR) and percentage of INRs in range (PINRR) was undertaken among 991 White, Afro-Caribbean and South-Asian AF patients [overall mean (SD) age 71.6 (9.4) years; 55% male; mean (SD) CHA₂DS₂-VASc score 3.4(1.6)] over a median of 5.2 years.

Results: Despite similar INR monitoring intensity, mean (SD) TTR and PINRR were significantly lower in South-Asians [TTR 60.5% vs. 67.9%; PINRR 51.6%, vs. 58.8% respectively] and Afro-Caribbeans [TTR 61.3% vs. 67.9%; PINRR 53.1% vs. 58.8% respectively] compared to Whites. [Table]: In logistic regression analyses, non-white ethnicity [TTR < 70%, OR 2.62 95%CI (1.67-4.10); p < 0.001 and PINRR < 70%, OR 3.47 95%CI (1.44-8.34); p = 0.005] and anaemia [TTR < 70%, OR 1.65 95%CI (1.00-2.70); p < 0.05 and PINRR < 70%, OR 6.27 95% CI (1.89-20.94); p = 0.003] were independent predictors of both TTR <70% and PINRR < 70% respectively.

Conclusions: Despite similar intensity INR-monitoring, ethnic differences in the quality of anticoagulation control are evident, with South-Asians and Afro-Caribbeans having poorer INR control compared to Whites. Non-white ethnicity was the strongest independent predictor of poor anticoagulation control. Interventions need to be implemented to improve the quality of anticoagulation control, particularly among ethnic minority patients.