1.
The HIPOGAIA study: Monitoring of oral anticoagulation with vitamin K antagonists in the municipality of Gaia.
Guedes, M, Rego, C
Revista portuguesa de cardiologia : orgao oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology : an official journal of the Portuguese Society of Cardiology. 2016;(9):459-65
Abstract
INTRODUCTION Anticoagulant therapy is an effective measure in preventing thromboembolic adverse events. Of the diseases in which this treatment is indicated, atrial fibrillation (AF) has the highest incidence worldwide, with a prevalence of 1.5-2%. OBJECTIVES To assess the quality of monitoring of patients with non-valvular AF under oral anticoagulation with vitamin K antagonists in Vila Nova de Gaia healthcare units. METHODS This was a retrospective observational analytical study of the population registered at the 37 healthcare units of the Vila Nova de Gaia and Espinho health center area under oral anticoagulation with vitamin K antagonists during 2014. The data were collected using TAONet(®) software. The variables studied were health units, age, gender, INR value, time in therapeutic range (TTR) and medication. TTR was calculated for each patient using the Rosendaal linear interpolation method. It was stipulated that each patient should have undergone at least six INR measurements. Data were analyzed using Microsoft Excel(®) 2010 and SPSS(®) version 21, using descriptive and inferential statistical techniques. RESULTS A total of 479 patients with non-valvular AF were studied, corresponding to 5883 INR tests. Mean TTR was 67.4±6.5%, and 35.3% of patients exhibited poor control (TTR <60%). DISCUSSION Our study showed moderate control of coagulation parameters, but better than in many international clinical trials and in another Portuguese observational study. Nevertheless, there is still room for improvement in anticoagulation monitoring in primary health care.
2.
Alternative calculations of individual patient time in therapeutic range while taking warfarin: results from the ROCKET AF trial.
Singer, DE, Hellkamp, AS, Yuan, Z, Lokhnygina, Y, Patel, MR, Piccini, JP, Hankey, GJ, Breithardt, G, Halperin, JL, Becker, RC, et al
Journal of the American Heart Association. 2015;(3):e001349
Abstract
BACKGROUND In the ROCKET AF (Rivaroxaban-Once-daily, oral, direct Factor Xa inhibition Compared with vitamin K antagonism for prevention of stroke and Embolism Trial in Atrial Fibrillation) trial, marked regional differences in control of warfarin anticoagulation, measured as the average individual patient time in the therapeutic range (iTTR) of the international normalized ratio (INR), were associated with longer inter-INR test intervals. The standard Rosendaal approach can produce biased low estimates of TTR after an appropriate dose change if the follow-up INR test interval is prolonged. We explored the effect of alternative calculations of TTR that more immediately account for dose changes on regional differences in mean iTTR in the ROCKET AF trial. METHODS AND RESULTS We used an INR imputation method that accounts for dose change. We compared group mean iTTR values between our dose change-based method with the standard Rosendaal method and determined that the differences between approaches depended on the balance of dose changes that produced in-range INRs ("corrections") versus INRs that were out of range in the opposite direction ("overshoots"). In ROCKET AF, the overall mean iTTR of 55.2% (Rosendaal) increased up to 3.1% by using the dose change-based approach, depending on assumptions. However, large inter-regional differences in anticoagulation control persisted. CONCLUSIONS TTR, the standard measure of control of warfarin anticoagulation, depends on imputing daily INR values for the vast majority of follow-up days. Our TTR calculation method may better reflect the impact of warfarin dose changes than the Rosendaal approach. In the ROCKET AF trial, this dose change-based approach led to a modest increase in overall mean iTTR but did not materially affect the large inter-regional differences previously reported. CLINICAL TRIAL REGISTRATION URL: ClinicalTrials.gov. Unique identifier: NCT00403767.
3.
Impact of global geographic region on time in therapeutic range on warfarin anticoagulant therapy: data from the ROCKET AF clinical trial.
Singer, DE, Hellkamp, AS, Piccini, JP, Mahaffey, KW, Lokhnygina, Y, Pan, G, Halperin, JL, Becker, RC, Breithardt, G, Hankey, GJ, et al
Journal of the American Heart Association. 2013;(1):e000067
Abstract
BACKGROUND Vitamin K antagonist (VKA) therapy remains the most common method of stroke prevention in patients with atrial fibrillation. Time in therapeutic range (TTR) is a widely cited measure of the quality of VKA therapy. We sought to identify factors associated with TTR in a large, international clinical trial. METHODS AND RESULTS TTR (international normalized ratio [INR] 2.0 to 3.0) was determined using standard linear interpolation in patients randomized to warfarin in the ROCKET AF trial. Factors associated with TTR at the individual patient level (i-TTR) were determined via multivariable linear regression. Among 6983 patients taking warfarin, recruited from 45 countries grouped into 7 regions, the mean i-TTR was 55.2% (SD 21.3%) and the median i-TTR was 57.9% (interquartile range 43.0% to 70.6%). The mean time with INR <2 was 29.1% and the mean time with an INR >3 was 15.7%. While multiple clinical features were associated with i-TTR, dominant determinants were previous warfarin use (mean i-TTR of 61.1% for warfarin-experienced versus 47.4% in VKA-naïve patients) and geographic region where patients were managed (mean i-TTR varied from 64.1% to 35.9%). These effects persisted in multivariable analysis. Regions with the lowest i-TTRs had INR distributions shifted toward lower INR values and had longer inter-INR test intervals. CONCLUSIONS Independent of patient clinical features, the regional location of medical care is a dominant determinant of variation in i-TTR in global studies of warfarin. Regional differences in mean i-TTR are heavily influenced by subtherapeutic INR values and are associated with reduced frequency of INR testing. CLINICAL TRIAL REGISTRATION URL: ClinicalTrials.gov. Unique identifier: NCT00403767.