Anticoagulation control of warfarin in anticoagulation medication therapy adherence clinics

Abstract Background Warfarin therapy remains essential in anticoagulation management and its quality is measured by the time in therapeutic range (TTR). In Malaysia, some healthcare centres provide the Anticoagulation Medication Therapy Adherence Clinic (ACMTAC) service for warfarin management, which is managed by pharmacists. Aim To evaluate overall TTR and to analyse the occurrence of thromboembolic and bleeding complications in warfarin patients. Method This cross‐sectional, retrospective cohort study included patients who received warfarin treatment over a 3‐year period (2019–2021). Data were collected from 49 healthcare centres in Malaysia with ACMTAC services. TTR was calculated using the Rosendaal method from international normalised ratio (INR) data acquired across these centres. TTR ≥ 65% was defined as good control of anticoagulation therapy. Ethical approval was granted by the Medical Research and Ethics Committee, Ministry of Health Malaysia (Reference no: NMRR‐ 21‐779‐59275) and the study conforms with the Declaration of Helsinki. Results The mean age (±standard deviation [SD]) of the 1464 included patients was 60.3 (±13.1) years, and 732 (50.0%) were male. Atrial fibrillation (65.7%) and valve replacement (23.1%) were the main indications for warfarin therapy. From 2019 to 2021, the annual mean TTR (±SD) were 63.1% (±24.5%), 64.0% (±25.0%), and 64.1% (±26.3%) respectively. For three consecutive years, more than 49% of patients achieved good control of anticoagulation therapy. Among the 49 centres, over 24 (49.0%) achieved a mean TTR of ≥65%, and the mean TTR varied significantly between centres (p < 0.001). The occurrence of bleeding and thromboembolic events was 227 (15.5%) and 15 (1.0%) respectively. Conclusion In Malaysia, the anticoagulation control of warfarin under ACMTAC management is moderate, with about half of patients demonstrating good control levels. Over a 3‐year observation period, there was variation in TTR among the centres.