Jasper H A van Miert1, Nic J G M Veeger2, Karina Meijer3. 1. Department of Hematology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; Certe Thrombosis Service Groningen, Groningen, the Netherlands. Electronic address: j.h.a.van.miert@umcg.nl. 2. Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands. 3. Department of Hematology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
Abstract
INTRODUCTION: Vitamin K antagonist therapy is safest and most effective with a high time within the therapeutic range (TTR). The TTR is difficult to calculate in the consultation room, therefore physicians need an easier-to-use tool to predict poor VKA control. We explored the prognostic value of subtherapeutic INRs on future TTR in two settings: MATERIALS AND METHODS: Retrospective cohort of 17,711 patients from a dedicated thrombosis service, using acenocoumarol (target range 2.0-3.0), with a "streak" defined as four consecutive INRs <2.0. RESULTS AND CONCLUSIONS: Clinical review setting: The occurrence of any streak in the last 180 days or 1 year increased the odds of a TTR <45%: ORs 2.84 (95% CI 2.41-3.34) and 3.25 (95% CI 2.72-3.87), respectively. Day-to-day INR management setting: A current streak increases the odds of poor TTR over the next 90 days 3.58 (95% CI 2.64-4.87) fold. We conclude that a streak of four consecutive subtherapeutic INRs can aid physicians in flagging at-risk patients.
INTRODUCTION:Vitamin K antagonist therapy is safest and most effective with a high time within the therapeutic range (TTR). The TTR is difficult to calculate in the consultation room, therefore physicians need an easier-to-use tool to predict poor VKA control. We explored the prognostic value of subtherapeutic INRs on future TTR in two settings: MATERIALS AND METHODS: Retrospective cohort of 17,711 patients from a dedicated thrombosis service, using acenocoumarol (target range 2.0-3.0), with a "streak" defined as four consecutive INRs <2.0. RESULTS AND CONCLUSIONS: Clinical review setting: The occurrence of any streak in the last 180 days or 1 year increased the odds of a TTR <45%: ORs 2.84 (95% CI 2.41-3.34) and 3.25 (95% CI 2.72-3.87), respectively. Day-to-day INR management setting: A current streak increases the odds of poor TTR over the next 90 days 3.58 (95% CI 2.64-4.87) fold. We conclude that a streak of four consecutive subtherapeutic INRs can aid physicians in flagging at-risk patients.