Objective: To predict the quality of anticoagulation control in patients with atrial fibrillation (AF) receiving warfarin in Thailand.

Materials and Methods: The present study retrospectively recruited Thai AF patients receiving warfarin for three months or longer between June 2012 and December 2017 in Central Chest Institute of Thailand. The patients were classified into those with SAMe-TT₂R₂ of 2 or less, and 3 or more. The Chi-square test or Fisher’s exact test was used to compare the proportion of the patients with poor time in therapeutic range (TTR) between the two groups of SAMe-TT₂R₂ score. The discrimination performance of SAMe-TT₂R₂ score was demonstrated with c-statistics.

Results: Ninety AF patients were enrolled. An average age was 69.89±10.04 years. Most patients were persistent AF. An average CHA₂DS₂-VASc, SAMe-TT₂R₂, and HAS-BLED score were 3.68±1.51, 3.26±0.88, and 1.98±0.85, respectively. The present study showed the increased proportion of AF patients with poor TTR with higher SAMe-TT₂R₂ score. The AF patients with SAMe-TT₂R₂ score of 3 or more had a larger proportion of patients with poor TTR than those with SAMe-TT₂R₂ score of 2 or less with statistical significance when TTR was below 70% (p=0.03) and 65% (p=0.04), respectively. The discrimination performance of SAMe-TT₂R₂ score was demonstrated with c-statistics of 0.60, 0.59, and 0.55 when TTR was below 70%, 65% and 60%, respectively.

Conclusion: Thai AF patients receiving warfarin had a larger proportion of patients with poor TTR when the SAMe-TT₂R₂ score was higher. The score of 3 or more could predict poor quality of anticoagulation control in those patients.

Keywords: Time in therapeutic range, Poor quality of anticoagulation control, Warfarin, SAMe-TT₂R₂, Labile INR

DOI: doi.org/10.35755/jmedassocthai.2020.06.10827

Received 28 Oct 2019 | Revised 20 Apr 2020 | Accepted 27 Apr 2020