Is the time in therapeutic range using the ratio of tests equivalent to the Rosendaal method?

Abstract

The percentage of time in therapeutic range (TTR) is a measure of anticoagulation quality with vitamin K antagonists (VKAs). The method most commonly used in clinical trials is the Rosendaal TTR. However, the application of this method in daily practice for clinical decision lacks appropriate instruments. We aimed to evaluate the percentage of tests within the target international normalized ratio (INR) (tests ratio) as a surrogate of Rosendaal TTR. We performed an observational and retrospective study to evaluate the TTR according to the Rosendaal method and tests ratio. We included all outpatients who attended the cardiology anticoagulation clinic of a Portuguese hospital (2011-2013), whose target INR was 2.0-3.0. Three hundred and seventy-seven VKA-treated patients followed for a mean 1.3 years were evaluated. Rosendaal methold and tests ratio significantly correlated (Rho Spearman 0.88, P < 0.001), but the Bland-Altman plot evaluation showed a clinically relevant data dispersion [95% confidence interval (95% CI) -12.9 to 23.1] around a mean difference in TTR -5.1% using the tests ratio method. The linear regression Passing-Bablok confirmed the existence of significant data dispersion and systematic differences. The tests ratio less than 60% had a sensitivity of 91.6%, specificity of 72.3%, positive predictive value (PPV) of 72.2% and negative predictive value (NPV) of 91.6%, for the diagnosis of patients inadequately anticoagulated (Rosendaal TTR <60%). Tests ratio had a c-statistics of 0.94 (95% CI 0.91-0.96). Number of tests in 6 months had a c-statistics of 0.70 (95% CI 0.65-0.75). Tests ratio underestimated TTR in 5% and was not considered equivalent to Rosendaal TTR due to the high variability between methods. Nevertheless, the use of tests ratio less than 60% may be a reasonable option to detect inadequate anticoagulation, as it is a sensitive method and excluded most of the patients with adequate control.

Comparison of international normalized ratio audit parameters in patients enrolled in GARFIELD‐AF and treated with vitamin K antagonists

“…The study was a retrospective analysis of 633 patients managed by a university hospital‐based, pharmacist‐managed anticoagulation clinic in the USA, with 1 year of follow‐up. Recently, a retrospective cohort study of 377 VKA‐treated outpatients attending the cardiology anticoagulation clinic of a Portuguese hospital showed that FIR and TTR were significantly correlated but not equivalent, due to high variability between the parameters (Caldeira et al , ). Our study extends these findings by analysing data from an international cohort of 8445 prospective patients.…”

Factores asociados a la anticoagulación oral óptima en el adulto mayor con fibrilación auricular

“…Se calculó el TRT mediante el método de Rosendaal (18,19,20), considerándose como control óptimo TRT ≥60% y control subóptimo TRT <60%. Este es el valor utilizado en los estudios clínicos internacionales (19,20).…”

“…Se calculó el TRT mediante el método de Rosendaal (18,19,20), considerándose como control óptimo TRT ≥60% y control subóptimo TRT <60%. Este es el valor utilizado en los estudios clínicos internacionales (19,20). Los grupos fueron sometidos a análisis para determinar la asociación con los factores edad, género, grado de instrucción, dependencia funcional, deterioro cognitivo, comorbilidades, discontinuidad terapéutica y polifarmacia, así como el porcentaje de ACV y sangrado en ambos grupos.…”

“…19) and female gender (OR 3; CI: 1.62-5.81) were associated with optimal control. Conclusions: A great percentage of patients with indications for oral anticoagulation and at low risk of bleeding did not start it, and 50% of those who started it had suboptimal control.…”

“…Ciento cuarenta pacientes tuvieron indicación de anticoagulación, 94 (67,14%) iniciaron warfarina, 28 (19,72%) tuvo control óptimo y 66 (46,48%) subóptimo. La edad ≥75 años (OR 25,5; IC: 7,8), no bajo grado de instrucción (OR 8; IC 3,61), ≥3 comorbilidades (OR 4,5; IC 2,33-9,39), discontinuidad terapéutica (OR 2,75; IC 1,44-5,52) y polifarmacia (OR 4,2; IC 2,16-8,80) se asociaron con control subóptimo, mientras que independencia funcional (OR 4,3; IC 2,16-9,47), no deterioro cognitivo (OR 7,8; IC 3,19) y género femenino (OR 3; IC 1,62-5,81) al control óptimo. Conclusiones: Un gran porcentaje de pacientes con indicación de ACO y con bajo riesgo de sangrado no iniciaron terapia anticoagulante; y el 50% de quienes la iniciaron, tuvo un control subóptimo.…”