The stability of anticoagulation is a key indicator for assessing the efficacy of warfarin in atrial fibrillation, which is an important anticoagulation therapy for the disease. Existing studies show that the eligible rate of stability of warfarin anticoagulation is rather unsatisfactory, and there are few studies on how to effectively calculate the stability of the treatment. Moreover, methods recommended in guidelines for estimating the stability of warfarin anticoagulation have limitations, with no effective suggestions for calculating stability of warfarin anticoagulation in the early stage of treatment.

To assess the practical efficacy of "double six definitions" in guideline-recommended method for estimating the stability of warfarin anticoagulation〔using INR data monitored for at least six months but excluding the data within the first six weeks〕, providing a reference for improving the method for calculating the stability of warfarin anticoagulation.

Participants with persistent non-valvular atrial fibrillation (n=126) were recruited from Jiujiang No.1 People's Hospital from January 2019 to December 2020. All of them received warfarin anticoagulant therapy and outpatient or inpatient follow-ups for understanding the coagulation status. The stability of warfarin anticoagulation was described using time in therapeutic range (TTR) calculated by different methods, namely using INR data in a 7-12-month follow-up period with or without removal of INR data in the first 6 weeks, and INR data in 12 consecutive months of follow-up with or without removal of INR data in the first 6 weeks, and the results were compared with the TTR calculated by "double six definitions".

Calculating the TTR using INR data of 7-12 months: there were no significant differences between the TTR calculated using INR data of 7, 8, 9, 10, 11 or 12 months with and without the first 6-week INR data (P>0.05) . Calculating the TTR using INR data of 12 consecutive months: when INR data in the first 6 weeks of follow-up were removed, the TTR at the first and second months of follow-up could not be calculated using the set formula, and it was deemed to be 0. There was significant difference between TTR calculated with and without INR data in the first 6 weeks at 1- or 2-month follow-up (P<0.001) . There was no significant difference between TTR calculated with and without INR data in the first 6 weeks at 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11- or 12-month follow-up (P > 0.05) . The TTR calculated using INR data of 7 to 12 months of follow-up was similar to that calculated using INR data at one time point of the second half period (7 to 12 months) within the 12-month follow-up under the condition of removing the INR data of the first 6 weeks (P>0.05) , and the same thing was found when the INR data of the first 6 weeks were not removed (P>0.05) . Furthermore, there were no significant differences in TTR calculated using INR data of 7 to 12 months of follow-up and using INR data of 12 consecutive months of follow-up regardless of whether the INR data of the first 6 weeks were removed or not (P>0.05) .

In the calculation of the stability of warfarin anticoagulation in atrial fibrillation, the INR data in the first 6 weeks might be included, and the baseline follow-up time for monitoring INR might not necessarily be greater than 6 months.

华法林在心房颤动患者的抗凝治疗中具有重要地位，而其抗凝治疗稳定性是评价药物疗效的重要指标，现有研究均显示华法林抗凝治疗稳定性的达标率较低，对于如何有效计算抗凝治疗稳定性的研究少见；现有指南中推荐的计算方法存在局限性，对于服药前期患者的达标率计算则未能提出有效建议。

探索指南中华法林抗凝治疗稳定性计算方法"需要不少于6个月的国际标准化比值（INR）监测数据且需要去除前6周的数据"定义（以下简称"双6定义"）对抗凝治疗稳定性计算结果的影响，以期为改进华法林抗凝治疗稳定性的计算方法提供参考。

选取2019年1月至2020年12月就诊于九江市第一人民医院的126例诊断为持续性非瓣膜性心房颤动且采用华法林抗凝治疗、同时进行了门诊或住院凝血功能随访检查的患者作为研究对象，计算"去除与不去除前6周INR数据"以及"随访时间>6个月与随访时间为12个月"的达标时间百分比（TTR），并与"双6定义"计算的TTR进行对比分析。

随访时间>6个月：随访7、8、9、10、11、12个月去除与不去除前6周INR数据计算的TTR比较，差异均无统计学意义（P>0.05）。随访时间为12个月：当TTR计算时间基线设置为12个月且去除前6周INR数据时，随访第1个月与第2个月时的TTR无法按设定的公式进行计算，视TTR为0；随访1、2个月去除与不去除前6周INR数据计算的TTR比较，差异有统计学意义（P<0.001）；随访3、4、5、6、7、8、9、10、11、12个月去除与不去除前6周INR数据计算的TTR比较，差异均无统计学意义（P>0.05）。去除前6周INR数据：随访时间>6个月与随访时间12个月时随访7~12个月TTR比较，差异均无统计学意义（P>0.05）；不去除前6周INR数据：随访时间>6个月与随访时间为12个月时随访7~12个月TTR比较，差异均无统计学意义（P>0.05）。随访7~12个月随访时间>6个月且去除前6周INR数据、随访时间为12个月且去除前6周INR数据、随访时间>6个月且不去除前6周INR数据、随访时间12个月且不去除前6周INR数据计算的TTR比较，差异均无统计学意义（P>0.05）。

华法林抗凝治疗稳定性的计算中可以考虑不去除前6周的数据，计算基线时间不一定必须要求>6个月。