Clinical versus fixed warfarin dosing and the impact on quality of anticoagulation (The ClinFix trial).

Different dosing strategies exist to initiate warfarin, most commonly fixed warfarin dosing (FWD), clinical warfarin dosing (CWD), and genetic-guided warfarin dosing (GWD). Landmark trials have shown GWD to be superior when compared to FWD in the EU-PACT trial or CWD in the GIFT trial. COAG trial did not show differences between GWD and CWD. We aim to compare the anticoagulation quality outcomes of CWD and FWD. This is a prospective cohort study with a retrospective comparator. Recruited subjects in the CWD (prospective) arm were initiated on warfarin according to the clinical dosing component of the algorithm published in www.warfarindosing.org. The primary efficacy outcome was the percentage time in the therapeutic range (PTTR) from day 3 to 6 till day 28 to 35. The study enrolled 122 and 123 patients in the CWD and FWD, respectively. The PTTR did not differ statistically between CWD and FWD (62.2 ± 26.2% vs. 58 ± 25.4%, p = 0.2). There was also no difference between both arms in the percentage of visits with extreme subtherapeutic international normalized ratio (INR) (<1.5; 15 ± 18.3% vs. 16.8 ± 19.1%, p = 0.44) or extreme supratherapeutic INR (>4; 7.7 ± 14.7% vs. 7.5 ± 12.4%, p = 0.92). We conclude that CWD did not improve the anticoagulation quality parameters compared to the FWD method.

Drive-up INR testing and phone-based consultations service during COVID-19 pandemic in a pharmacist-lead anticoagulation clinic in Qatar: Monitoring, clinical, resource utilization, and patient- oriented outcomes.

Background: Coronavirus disease 2019 (COVID-19) pandemic has resulted in unprecedented pressure on healthcare systems and led to widespread utilization of telemedicine or telehealth services. Combined with teleclinics, using drive-up fingerstick International normalized ratio (INR) testing was recommended to decrease exposure risk of anticoagulation patients. Objective: To evaluate the impact of transitioning from clinic-based anticoagulation management services to drive-up and phone-based services during COVID-19 pandemic in Qatar. Methods: The study comprised of two components: a retrospective cohort study of all eligible patients who attended anticoagulation clinic over 1-year period (6 months before and 6 months after service transition) and a cross-sectional survey of eligible patients who agreed to provide data about their satisfaction with the new service. Monitoring parameters, clinical outcomes, and resource utilization related to warfarin therapy were compared before and after service transition. Patients' experience was explored through a structured survey. Results: There was no statistically significant difference between clinic-based and phone-based anticoagulation services in mean time and number of visits within therapeutic range (P = .67; P = .06 respectively); mean number of extreme subtherapeutic and supratherapeutic INR values (P = .32 and P = .34, respectively); incidence of thromboembolic complications and warfarin related hospitalization. There was one reported bleeding and one emergency visit (0.9%) in the phone-based group vs none in the clinic-based group. Frequency of INR testing and compliance to attending clinics appointments declined significantly (P = .002; P = .001, respectively). Overall, patients were highly satisfied with the new service. The majority of patients found it better (51.6%) or just as good as the traditional service (44.5%). Patients who preferred the new service were significantly younger than their counterparts (P = .005). Conclusion: The service of drive-up INR testing and phone-based consultations was shown to be comparable to traditional anticoagulation service, a finding that supports maintaining such services as part of the new normal after the pandemic is over.

Anticoagulation clinic drive-up service during COVID-19 pandemic in Qatar.

Coronavirus Disease 2019 (COVID-19) is a pandemic affecting many countries worldwide. Given the increasing incidence especially in elderly and individuals with comorbid conditions, it is advised by health authorities to stay home if possible, maintain social distancing and stay away from those who are sick or could be infected. Patients with comorbidities especially cardiovascular disease are at higher risk of getting infected with COVID-19 and have worse prognosis. Among efforts to safely manage warfarin patients during this pandemic, we introduced a hospital drive-up anticoagulation testing service. This service can reduce the risk of exposure of anticoagulation patients to COVID-19 by reducing the contact time with the different personnel at the hospital and by maintaining those patients at a safe distance from others.

The effect of genetic and nongenetic factors on warfarin dose variability in Qatari population.

The objective of this study is to estimate the prevalence of VKORC1, CYP2C9, and CYP4F2 genetic variants and their contribution to warfarin dose variability in Qataris. One hundred and fifty warfarin-treated Qatari patients on a stable dose and with a therapeutic INR for at least three consecutive clinic visits were recruited. Saliva samples were collected using Oragene DNA self-collection kit, followed by DNA purification and genotyping via TaqMan Real-Time-PCR assay. The population was stratified into derivation and validation cohorts for the dosing model. The minor allele frequency (MAF) of VKORC1 (-1639G>A) was A (0.47), while the MAF's for the CYP2C9*2 and *3 and CYP4F2*3 were T (0.12), C (0.04) and T (0.43), respectively. Carriers of at least one CYP2C9 decreased function allele (*2 or *3) required lower median (IQR) warfarin doses compared to noncarriers [24.5 (14.5) mg/week vs. 35 (21) mg/week, p < 0.001]. Similarly, carriers of each additional copy of (A) variant in VKORC1 (-1639G>A) led to reduction in warfarin dose requirement compared to noncarriers [21(7.5) vs. 31.5(18.7) vs. 43.7(15), p < 0.0001]. CYP4F2*3 polymorphism on the other hand was not associated with warfarin dose. Multivariate analysis on the derivation cohort (n = 104) showed that a dosing model consisting of hypertension (HTN), heart failure (HF), VKORC1 (-1639G>A), CYP2C9*2 & *3, and smoking could explain 39.2% of warfarin dose variability in Qataris (P < 0.001). In the validation cohort (n = 45), correlation between predicted and actual warfarin doses was moderate (Spearman's rho correlation coefficient = 0.711, p < 0.001). This study concluded that VKORC1 (-1639G>A), CYP2C9*2 & *3 are the most significant predictors of warfarin dose along with HTN, HF and smoking.