Rationale, design, and preliminary results of the Quebec Warfarin Cohort Study.

Over- and undercoagulation with warfarin are 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 1059 new warfarin users, with prospective follow-up using telephone questionnaires every 3 months for 1 year, and using healthcare administrative databases (RAMQ and Med-Echo) for 5 years 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 therapeutic range, anticoagulation control, warfarin dose, bleeding, and thromboembolic events. We report baseline characteristics and outcomes after 1 year of follow-up. Poor anticoagulation control was defined as time in therapeutic range <60% in the 3- to 12-month interval. Participants had a mean age of 71 years, and 62% were men. The most common indication for warfarin was atrial fibrillation (87%). Mean time in therapeutic range was 56% (±25%) in the 3 months 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; for major bleeding events, 3.3 events per 100 person-years. Independent predictors of poor anticoagulation control were chronic kidney disease, heart failure, dyslipidemia, and age. The QWC represents a good research cohort to investigate clinical and genetic factors in a warfarin-anticoagulated population.

Perreault S ，Shahabi P ，Côté R ，Dumas S ，Rouleau-Mailloux É ，Feroz Zada Y ，Provost S ，Mongrain I ，Dorais M ，Huynh T ，Kouz S ，Diaz A ，Blostein M ，de Denus S ，Turgeon J ，Ginsberg J ，Lelorier J ，Lalonde L ，Busque L ，Kassis J ，Talajic M ，Tardif JC ，Dubé MP ... -  《-》

Genetic and Non-Genetic Factors Affecting the Quality of Anticoagulation Control and Vascular Events in Atrial Fibrillation.

Warfarin has a narrow therapeutic window. We hypothesized that genetic factors related to warfarin metabolism (CYP2C9) and activity (VKORC1) would show stronger associations than modifiable factors with the quality of anticoagulation control and risks for thromboembolism and hemorrhage. In this retrospective cohort analysis, clinical and genetic data were collected from 380 patients with atrial fibrillation (AF) who were followed for an average observation period of 4 years. We evaluated the factors associated with time in therapeutic range (TTR, international normalized ratio [INR]: 2-3) and vascular events (either thromboembolic or hemorrhagic), including both genetic (CYP2C9 and VKORC1 genotype) and modifiable factors (anticoagulation service and warfarin dose assessment interval). The genotypic frequency of CYP2C9*3 (rs1057910) was 9.5% and that of VKORC1 1173C>T (rs9934438) was 16.3%. TTR showed dependence on VKORC1 polymorphism: TTR was higher in carriers of the VKORC1 1173C>T than of the VKORC1 TT genotype (61.7 ± 16.0% versus 56.7 ± 17.4%, P = .031). Multivariate testing showed that the VKORC1 genotype and anticoagulation service were independently related to labile INRs (TTR <65%). Vascular events were observed in 66 patients (18.4%) during the study period. A Cox proportional hazard model showed that the use of anticoagulation service and patients' characteristics, such as AF-thromboembolic risk (CHA2DS2-VASc score: Congestive heart failure, Hypertension, Age 75 years or older, Diabetes mellitus, previous Stroke or transient ischemic attack, Vascular disease, Age 65 to 74 years, female) and consequence (neurologic disability), but not genetic factors, were independently associated with vascular events. Both genetic factor (VKORC1 genotype) and clinical efforts (anticoagulation service) influenced the quality of anticoagulation control. However, clinical events were more strongly associated with patient characteristics and clinical efforts than with genetic factors.

Park YK ，Lee MJ ，Kim JH ，Lee JS ，Park RW ，Kim GM ，Chung CS ，Lee KH ，Kim JS ，Lee SY ，Bang OY ... -  《-》

Pharmacogenetics of Warfarin in a Diverse Patient Population.

Mak M ，Lam C ，Pineda SJ ，Lou M ，Xu LY ，Meeks C ，Lin C ，Stone R ，Rodgers K ，Mitani G ... -  《-》

Long-term outcomes of elderly patients with CYP2C9 and VKORC1 variants treated with vitamin K antagonists.

Essentials The long-term effects of VKORC1 and CYP2C9 variants on clinical outcomes remains unclear. We followed 774 patients ≥65 years with venous thromboembolism for a median duration of 30 months. Patients with CYP2C9 variants are at increased risk of death and non-major bleeding. Patients with genetic variants have a slightly lower anticoagulation quality only. Background The long-term effect of polymorphisms of the vitamin K-epoxide reductase (VKORC1) and the cytochrome P450 enzyme gene (CYP2C9) on clinical outcomes remains unclear. Objectives We examined the association between CYP2C9/VKORC1 variants and long-term clinical outcomes in a prospective cohort study of elderly patients treated with vitamin K antagonists for venous thromboembolism (VTE). Methods We followed 774 consecutive patients aged ≥ 65 years with acute VTE from nine Swiss hospitals for a median duration of 30 months. The median duration of initial anticoagulant treatment was 9.4 months. The primary outcome was the time to any clinical event (i.e. the composite endpoint of overall mortality, major and non-major bleeding, and recurrent VTE. Results Overall, 604 (78%) patients had a CYP2C9 or VKORC1 variant. Three hundred and thirty-four patients (43.2%) had any clinical event, 119 (15.4%) died, 100 (12.9%) had major and 167 (21.6%) non-major bleeding, and 100 had (12.9%) recurrent VTE. After adjustment, CYP2C9 (but not VKORC1) variants were associated with any clinical event (hazard ratio [HR], 1.34; 95% confidence interval [CI], 1.08-1.66), death (HR, 1.74; 95% CI, 1.19-2.52) and clinically relevant non-major bleeding (sub-hazard ratio [SHR], 1.39; 95% CI, 1.02-1.89), but not with major bleeding (SHR, 1.03; 95% CI, 0.69-1.55) or recurrent VTE (SHR, 0.95; 95% CI, 0.62-1.44). Patients with genetic variants had a slightly lower anticoagulation quality. Conclusions CYP2C9 was associated with long-term overall mortality and non-major bleeding. Although genetic variants were associated with a slightly lower anticoagulation quality, there was no relationship between genetic variants and major bleeding or VTE recurrence.

Nagler M ，Angelillo-Scherrer A ，Méan M ，Limacher A ，Abbal C ，Righini M ，Beer JH ，Osterwalder J ，Frauchiger B ，Aschwanden M ，Matter CM ，Kucher N ，Cornuz J ，Banyai M ，Husmann M ，Staub D ，Mazzolai L ，Hugli O ，Rodondi N ，Aujesky D ... -  《-》

CYP2C9 and VKORC1 genotyping for the quality of long-standing warfarin treatment in Russian patients.

Panchenko E ，Kropacheva E ，Dobrovolsky A ，Titaeva E ，Zemlyanskaya O ，Trofimov D ，Galkina I ，Lifshits G ，Vereina N ，Sinitsin S ，Vorobyeva N ，Grehova L ，Zateyshchikov D ，Zotova I ，Vavilova T ，Sirotkina O ，Grontkovskaya A ... -  《-》