Patients’time in therapeutic range on warfarin among atrial fibrillation patients in Warfarin Medication Therapy Adherence Clinic

BACKGROUND The quality of warfarin therapy can be determined by the time in the therapeutic range(TTR)of international normalized ratio(INR).The estimated minimum TTR needed to achieve a benefit from warfarin therapy is≥60%.AIM To determine TTR and the predictors of poor TTR among atrial fibrillation patients who receive warfarin therapy.METHODS A retrospective observational study was conducted at a cardiology referral center in Selangor,Malaysia.A total of 420 patients with atrial fibrillation and under follow-up at the pharmacist led Warfarin Medication Therapeutic Adherence Clinic between January 2014 and December 2018 were included.Patients’clinical data,information related to warfarin therapy,and INR readings were traced through electronic Hospital Information system.A data collection form was used for data collection.The percentage of days when INR was within range was calculated using the Rosendaal method.The poor INR control category was defined as a TTR<60%.Predictors for poor TTR were further determined by using logistic regression.RESULTS A total of 420 patients[54.0%male;mean age 65.7(10.9)years]were included.The calculated mean and median TTR were 60.6%±20.6%and 64%(interquartile range 48%-75%),respectively.Of the included patients,57.6%(n=242)were in the good control category and 42.4%(n=178)were in the poor control category.The annual calculated mean TTR between the year 2014 and 2018 ranged from 59.7%and 67.3%.A high HAS-BLED score of≥3 was associated with poor TTR(adjusted odds ratio,2.525;95%confidence interval:1.6-3.9,P<0.001).CONCLUSION In our population,a high HAS-BLED score was associated with poor TTR.This could provide an important insight when initiating an oral anticoagulant for these patients.Patients with a high HAS-BLED score may obtain less benefit from warfarin therapy and should be considered for other available oral anticoagulants for maximum benefit.

Elderly Disabled Patients in Oral Anticoagulation Treatment: An Evaluation of a Bioanalyst-Led Management Program Reaching an Average of 72% of Time in Therapeutic Range

Introduction: The need for anticoagulation therapy increases with age, mainly due to the increased prevalence of atrial fibrillation. Time in therapeutic range (TTR) is a marker of the quality of the therapy as TTR is inversely correlated with adverse reactions. We developed a bioanalyst-led management program for control of warfarin treatment in elderly disabled patients in their own home and maintain a high TTR. Material and Methods: Residents in nursing home settings were included. Visiting nurses measured INR with a point of care testing device. If INR was within Therapeutic Range (TR), the nurse dosed warfarin unaltered. If INR was out of TR, the visiting nurse contacted a specially trained bioanalyst by phone. An explanation was sought, and a new dosage plan was made. Results: A total of 579 patients were included;356 females (61%). Mean age was 79.6 years. Approximately 10% were residents in nursing home settings and the rest in domiciliary care. TTR was 72%. The subtherapeutic values were 15% and supratherapeutic values 13%. In total, 139 patients died during the study period. Ten deaths could be related to possible side effects of warfarin treatment. Conclusions: Our results indicate that a bioanalyst-led program is able to simplify anticoagulation monitoring, while maintaining INR control similar to a specialized clinic. Furthermore, we avoided hospitalizations when INR was unacceptably high by treating the patient with oral vitamin-K at home. Our findings could be helpful when planning warfarin treatment in elderly, fragile patients.

Assessment of Oral Anticoagulation with Vitamin K Antagonists in Patients Living in a Low-Income Country of West Africa

Introduction: Despite the rise of direct oral anticoagulants (DOACs), vitamin K antagonists (VKA) remain the most widely used oral anticoagulants in developing countries. The aim of this study was to estimate the prevalence of good anticoagulation in patients treated with VKA in Lomé and describe associated factors. Methods: This was a cross-sectional study conducted from November 2019 to October 2020 in the cardiology departments of two University teaching hospitals in Lomé (CHU Sylvanus Olympio and CHU Campus), involving patients on VKA for ≥3 months, with a target international normalized ratio (INR) of 2.5 and a therapeutic margin between 2 and 3. The quality of anticoagulation was assessed by the time in therapeutic range (TTR) which was assessed by the Rosendaal method. Good anticoagulation was defined by a TTR > 70%. Results: A total of 344 patients were included (mean age = 58 ± 13.8 years, women = 56.1%). Indications for VKA treatment were represented by venous thromboembolic disease (43.3%), supraventricular arrhythmia (28.2%), severe left ventricular systolic dysfunction (19.8%) and pulmonary hypertension (8.7%). The average TTR was 47.6 ± 20.8%. The rate of good anticoagulation was 17.7%. Factors associated with good anticoagulation were the use of fluindione vs acenocoumarol (OR = 11.17;95% CI: 3.2 - 39.6;p = 0.0002), concomitant low-dose aspirin (OR 4.44;95% CI: 1.4 - 13.9;p = 0.01) and INR monitoring exclusively by the patient himself (OR = 4.92;95% CI: 1.5 - 16.3;p = 0.008). The rate of thromboembolic and hemorrhagic complications was each 2.6% and was not correlated with the quality of anticoagulation. Quality of anticoagulation by VKAs was poor in our practice. Factors associated with good anticoagulation were the use of fluindione vs acenocoumarol, concomitant low-dose aspirin and monitoring of INR exclusively by the patient himself. Conclusion: The quality of oral anticoagulation by VKAs could be improved in our practice by the creation of anticoagulation clinics for better therapeutic education of patients and efficient management of VKA dose, and the use of prescription assistance software.