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Acta Medica Colombiana

versão impressa ISSN 0120-2448


MIRANDA, Harold et al. Time in therapeutic range (TTR) in anticoagulation clinic. Reports of adverse events and factors associated with low TTR. Acta Med Colomb [online]. 2016, vol.41, n.1, pp.42-48. ISSN 0120-2448.

In the treatment of warfarin anticoagulation, reduction of thromboembolic events must be evaluated with the risk of bleeding. Time in therapeutic range (TTR) by the method of Rosendaal is a tool that values quality monitoring anticoagulant therapy and correlates with the presence of thromboembolic events or bleeding. In this study time therapeutic range (TTR), factors associated with lower (TTR) and adverse effects presented in the anticoagulation clinic are presented.

Methods and Results:

A descriptive cross-sectional study from 1° January 2011 and 29th February 2012.

2232 results of INR of 319 patients were assessed. 98550 days follow up. 44% (108) were men, 66% (211) women, average age 60.3 years, seven average visits / year, warfarin weekly dose of 29.8 mg. The weekly dose has an inverse relationship with age; in patients under 45 years 37.9 mg., and in patients over 75 years, 22.1 mg. The TTR increased from 48 to 54%, respectively.

Indications for anticoagulation: atrial fibrillation (AF) 38% (121), venous thromboembolic disease (VTE) 35% (112), prosthetic valves (PV) 17.5% (56) and emboli or arterial thrombosis (EA) 9.5% (30). 228 patients (71%) had a TTR average of 64%. (40-100), INR greater than 5 in 2.24% and INR less than 1.5 in 10.9%.

Minor bleeding: 16 patients (5%), major bleeding occurred in two patients (0.65%) and one adverse event of embolism (0.32%).

The factors associated with low TTR were male gender, venous thromboembolic disease, use of generic warfarin, age less than 55 years, time shorter than one year and less than five visits.


TTR is a useful measurement to establish the efficacy of anticoagulant therapy with warfarin. The goal of a 60% TTR ensures fewer adverse effects from bleeding or thrombosis. A low number of visits and anticoagulation less than a year are associated with low TTR. (Acta Med Colomb 2016; 41: 42-48).

Palavras-chave : anticoagulation clinic; Rosendaal method; warfarin; time therapeutic range.

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