Association between activated partial thromboplastin time, age and bleeding events in NVAF patients receiving dabigatran

Purpose The purpose of this study was to analyze the association between bleeding events and coagulation assays including activated partial thromboplastin time (APTT) and prothrombin time (PT), and to determine the risk factors for bleeding in Chinese patients with non-valvular atrial fibrillation (NVAF) receiving dabigatran. Methods We conducted a retrospective cohort study including NVAF patients receiving dabigatran 110 mg twice daily between March 2016 and November 2017. We obtained the clinical features and demographic data from the medical records and compared the baseline characteristics of the bleeding group and the no bleeding group. Receiver operating characteristic(ROC) curves and a logistic regression model were used to determine the relation between APTT and bleeding events and the predictors of bleeding. Model performance was evaluated using the derivation cohort and an independent validation cohort by area under the ROC curve (AUC). Results A total of 346 patients were included and bleeding events occurred in 39 (11.2%) patients. Patients with age over 65 years (OR = 2.56 [95% CI 1.20–5.43]), hypertension (OR = 2.42 [95% CI 1.11–5.26]), decreased renal function (OR = 4.27 [95% CI 1.22–14.91]) and with concomitant use of an antiplatelet drug (OR = 3.53 [95% CI 1.28–9.74]) showed higher risk for bleeding, and APTT value of the bleeding group was higher than the no bleeding group ( P = 0.014). By ROC analysis we found that the appropriate overall cut-off value the of APTT ratio was 1.30, with a sensitivity of 72% and specificity of 58%. Multivariate logistic regression showed that higher age ( P = 0.003; OR = 1.05 [95% CI 1.02–1.09]) and APTT ratio > 1.30 ( P = 0.002; OR = 3.20 [95% CI 1.23–6.73]) were independent risk factors for bleeding in patients with dabigatran therapy. The logistic regression model exhibited moderate discrimination ability, with an AUC of 0.73 [95% CI 0.65–0.81] and 0.77 [95% CI 0.59–0.96] in the derivation cohort ( n = 346) and the validation cohort ( n = 71) respectively. Conclusions Our study demonstrated that APTT ratio > 1.30 (at trough level) and higher age were independent risk factors for bleeding, and the logistic regression model based on these two predictors showed moderate performance, which may be useful for assessment of bleeding risk in NVAF patients with dabigatran therapy.