Evaluation of DOAC Dosing Among Various Renal Equations in Patients With Kidney Impairment and Elderly in Thailand

The Thai Food and Drug Administration (TFDA) has approved direct oral anticoagulant (DOAC) dosing based on estimated creatinine clearance, eCrCl (Cockcroft-Gault equation). However, other renal function equations are often used in practice for patients with kidney disease, leading to potential discrepancies in DOAC dosing recommendations. The actual DOAC dosing patterns in resource-limited countries remain underreported. This cross-sectional study included patients with renal impairment who were treated at the outpatient department of Siriraj Hospital, Mahidol University, Thailand. Patients received their first DOAC for atrial fibrillation from January 2019 to December 2022. The primary objective was to evaluate the percentage of DOAC prescriptions compliant with TFDA guidelines using eCrCl. We also examined dosing agreement when substituting estimated glomerular filtration rate, eGFR (CKD-EPI) for eCrCl. Patient factors and the incidence of stroke and bleeding over a one-year follow-up were also assessed. A total of 326 patients and 1587 DOAC prescriptions were analyzed. The mean patient age was 79.1 ± 9.2 years, with a mean eGFR of 45.6 ± 9.9 mL/min/1.73 m². TFDA-compliant dosing was observed in 68.2% of prescriptions. Dose disagreement between eGFR and eCrCl was 45%, with a trend toward overdosing using eGFR. An eGFR of less than 45 mL/min/1.73 m² was associated with dose discrepancies. Stroke and bleeding incidences were low, with no differences across DOAC types. While most Thai patients received appropriate DOAC dosing, one-third did not comply with TFDA guidelines. Using eGFR instead of eCrCl may result in dosing differences, particularly in moderate to severe renal impairment.