Turk Kardiyol Dern Ars. 2021; 49(6): 463-473 | DOI: 10.5543/tkda.2021.21015
Time in therapeutic range values of patients using warfarin and factors that influence time in therapeutic range
Lale Dinç Asarcıklı1
, Habibe Kafes2
, Taner Şen3
, Esra Gucuk İpek4
, Muhammet Cebeci5
, Murat Gül6
, Selçuk Kanat7
, Ahmet Temizhan21
Department of Cardiology, Dr. Siyami Ersek Cardiovascular and Thoracic Surgery Research and Training Hospital, İstanbul, Turkey2
Department of Cardiology, Health Sciences University Ankara City Hospital, Ankara, Turkey3
Department of Cardiology, Dumlupınar University School of Medicine, University Hospital, Kütahya, Turkey4
Department of Cardiology, Polatlı State Hospital, Ankara, Turkey5
Department of Cardiology, Söke State Hospital, Aydın, Turkey6
Department of Cardiology, Aksaray University School of Medicine, Aksaray, Turkey7
Department of Cardiology, Bursa Yüksek İhtisas Training and Research Hospital, Bursa, Turkey
OBJECTIVE The time in therapeutic range (TTR) of international normalized ratio (INR) is essential for the safety and efficacy of warfarin treatment. In this study, we aimed to determine TTR and the factors that affect TTR in patients using warfarin.
METHODS Patients taking warfarin for valvular and nonvalvular atrial fibrillation (AF) or prosthetic heart valves who were admitted to our cardiology outpatient clinic were enrolled. TTR was calculated using the linear interpolation method. The patients were analyzed according to warfarin indications and TTR efficiency (TTR ≥60%). Weekly warfarin dose, the duration of warfarin use, the frequency of INR visits per year, and the awareness of patients regarding target INR were noted.
RESULTS The TTR of 248 patients (aged 57.21±12.45 years, 33.1% male) was 55.92±27.84%, and 48.0% patients exhibited efficient TTR. Clinical and demographic characteristics (age, sex, socioeconomic status, and comorbidities) exerted no effect on TTR and TTR efficiency. The frequency of INR visits per year was 10.02±3.80. TTR was related to the frequency of annual INR visits (r=0.131, p=0.039). Only one-third (30.2%) of patients were aware of their target INR. The literacy of the patients and duration of warfarin use exerted a positive effect on awareness (p=0.011 and p=0.024, respectively).
CONCLUSION The findings of our study demonstrated that TTR and TTR efficiency were low and not associated with the characteristics of patients or indications. Unfortunately, in patients with valvular AF and prosthetic valves, warfarin is the sole drug that can be used. Thus, awareness and knowledge regarding target INR are essential to overcome poor anticoagulation monitoring with frequent INR visits.
How to cite this article
Lale Dinç Asarcıklı, Habibe Kafes, Taner Şen, Esra Gucuk İpek, Muhammet Cebeci, Murat Gül, Selçuk Kanat, Ahmet Temizhan. Time in therapeutic range values of patients using warfarin and factors that influence time in therapeutic range. Turk Kardiyol Dern Ars. 2021; 49(6): 463-473
Corresponding Author: Lale Dinç Asarcıklı, Türkiye