Quality of oral anticoagulation control in Chinese patients with non-valvular atrial fibrillation: a prospective controlled study

The sex, age, medical history, treatment, tobacco use, race risk (SAMe-TT₂R₂) Score; the sex, age, medical history, treatment, tobacco use, genotype combination (SAMe-TT₂G₂) Score; and the so-called modified SAMe-TT₂R₂ scores have been proposed to predict the anticoagulation quality for patients with non-valvular atrial fibrillation (NVAF). The data from a prospective controlled study is used to validate the SAMe-TT₂R₂ and SAMe-TT₂G₂ scores in Chinese NVAF patients treated with warfarin and to evaluate the association of factors with time in therapeutic range (TTR) to predict the quality of oral anticoagulation control.

A total of 379 patients with NVAF under warfarin treatment for a three-month follow-up were included in this prospective, multicenter study. The quality of oral anticoagulation control was evaluated by the TTR. The TTR was dichotomized for binary logistic regression analysis, using a cutoff point for classification as an inadequate (TTR < 65.0%) control.

The 379 NVAF patients had a mean TTR of 58.35 ± 26.33% and median SAMe-TT₂R₂ and SAMe-TT₂G₂ scores of 3 and 2, respectively. The discrimination performances of the SAMe-TT₂R₂ and SAMe-TT₂G₂ scores for inadequate anticoagulation control (TTR < 65.0%) were poor (c-index < 0.60). The gene frequency of CYP2C9*3 was 3.2% and that of VKORC1-1639 G > A was 89.3%. Genetic variation of CYP2C9*3 and VKORC1-1639 G > A did not affect TTR after initial treatment. The condition TTR < 65.0% was associated with an age below 60 without genotype-guided warfarin dose initiation and concomitant torasemide.

A warfarin-dosing algorithm used for initial treatment of patients older than 60 helps to achieve a better quality of oral anticoagulation control, whereas concomitant torasemide can produce a negative effect. These findings provide useful information for future investigations on the quality of oral anticoagulation control in Chinese anticoagulation clinical practice.