Impact of different renal function equations on direct oral anticoagulant concentrations.

The purpose of this study is to investigate the correlation between glomerular filtration rate (GFR) estimated by different renal function equations and non-vitamin K antagonist oral anticoagulant concentration. Atrial fibrillation patients who aged ≥ 20 years and used dabigatran, rivaroxaban, or apixaban for thromboembolism prevention were enrolled to collect blood samples and measure drug concentrations using ultra-high-performance liquid chromatography with tandem mass spectrometry. The GFR was estimated using the Cockroft-Gault formula (abbreviated as creatinine clearance, CrCL), Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI) featuring both creatinine and cystatin C, and the Modification of Diet in Renal Disease Study equation (MDRD). Multivariate regression was used to investigate the associations of different renal function estimates with drug concentrations. A total of 511 participants were enrolled, including 146 dabigatran users, 164 rivaroxaban users and 201 apixaban users. Compared to clinical trials, 35.4% of dabigatran, 4.9% of rivaroxaban, and 5.5% of apixaban concentrations were higher than the expected range (p < 0.001). CKD-EPI and MDRD estimates classified fewer patients as having GFR < 50 mL/min than CrCL in all 3 groups. Both CrCL and CKD-EPI were associated with higher-than-expected ranges of dabigatran or rivaroxaban concentrations. Nevertheless, none of the renal function equations was associated with higher-than-expected apixaban concentrations. For participants aged ≥ 75 years, CKD-EPI may be associated with higher-than-expected trough concentration of dabigatran. In conclusion, CrCL and CKD-EPI both can be used to identify patients with high trough concentrations of dabigatran or rivaroxaban. Among elderly patients who used dabigatran, CKD-EPI may be associated with increased drug concentration.