Clinical cardiology 2018 03 15() doi 10.1002/clc.22948
Over- and under-coagulation with warfarin is associated with hemorrhagic and thromboembolic events, respectively. Genetic and clinical factors affect warfarin response, and the causes of this variability remain unclear. We present descriptive statistics and test for predictors of poor anticoagulation control.
The Quebec Warfarin Cohort (QWC) comprises 1,059 new warfarin users, with prospective follow up using telephone questionnaires every 3 months for one year, and using healthcare administrative databases (RAMQ and Med-Echo) for 5-year prior to cohort entry and up to 10-years following active patient participation. Genetic material was collected and genotyping of CYP2C9 and VKORC1 genes was conducted. Measured outcomes included the percentage of time patients spent within, anticoagulation control, warfarin dose, bleeding, and thromboembolic events. We report the baseline characteristics and outcomes after 1-year of follow-up. Poor anticoagulation control was defined as TTR <60% in 3- to 12-month interval. RESULTS
Participants had a mean age of 71 years and 62% were men. The most common indication for warfarin was atrial fibrillation. Mean time in the therapeutic range (TTR) was 56% (±25) in the 3-month following warfarin initiation, and 70% (±21) in the 3- to 12-month interval. During follow up, the rate of stroke or systemic embolism was 1.8 events per 100 person-years and 3.3 events per 100 person-years for major bleeding events. Independent predictors of poor anticoagulation control were chronic kidney disease, heart failure, dyslipidemia, and age.
The QWC represents a good research opportunity to investigate clinical and genetic factors in a warfarin anticoagulated population.