Jornal Vascular Brasileiro
Jornal Vascular Brasileiro
Original Article

Comparison between the conventional method and a portable device for determination of INR

Determinação do INR: comparação entre método convencional e dispositivo portátil

André Camacho Oliveira Araújo; Rodrigo Borges Domingues; Bonno van Bellen

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CONTEXT:Anticoagulation with warfarin is considered the appropriate treatment for venous thromboembolism and other thrombotic pathologies. Regular INR control is required for dosage adjustment and therapeutic control. Use of portable monitoring systems optimizes management of these patients.OBJECTIVE: To compare INR measurements taken using the portable Coaguchek XS system in capillary blood with the standard laboratory method using venous blood.METHOD: Fifty-two samples each of venous and capillary blood were collected from nineteen patients on warfarin, who had been admitted to the Hospital da Beneficência Portuguesa de São Paulo, and analyzed using the conventional method and the Coaguchek XS system, respectively.RESULTS: Spearman's correlation coefficient ® for the overall performance of the two methods was 0.978 (p<0.0001; 95%CI 0.961-0.988). The Kappa measure of agreement for all patients was 76.8% (p<0.001; IC: 95% 0.975-0.561). Mean INR according to the Coaguchek XS system underestimated the values provided by the conventional method by -0.01 INR points, with a standard error of 0.342. Results for INR values greater than 3.5 were satisfactory with a correlation coefficient of 0.71, but without statistical significance (p>0.714).CONCLUSIONS: The Coaguchek XS system can be used to monitor prothrombin time in patients on oral anticoagulants, provided INR values greater than 3.5 are confirmed using the conventional laboratory method.


prothrombin time, blood coagulation, warfarin, venous thromboembolism


CONTEXTO: Anticoagulação por varfarina (warfarin) é considerada tratamento adequado para tromboembolismo venoso e outras patologias trombóticas. Deve ser realizada a mensuração do Índice Internacional Normalizado (INR) para ajuste de dosagem de medicamento para manutenção dos pacientes na faixa terapêutica. O uso de dispositivos portáteis otimiza o controle desses pacientes.OBJETIVO: Comparar as medidas do INR realizadas pelo sistema portátil Coaguchek XS, em sangue capilar, com o método laboratorial padrão em sangue venoso.MÉTODO: Dezenove pacientes em uso de varfarina, internados no Hospital da Beneficência Portuguesa de São Paulo, foram submetidos à coleta de 52 amostras analisadas pelo método convencional e coleta de sangue capilar para medida com o sistema Coaguchek XS.RESULTADOS: O coeficiente de correlação (r) de Spearman por meio da comparação de desempenho global entre os dois métodos foi de 0,978 (p<0,0001; IC: 95% 0,961-0,988). O percentual de concordância Kappa para todas as faixas foi de 76,8% (p<0,001; IC: 95% 0,975-0,561). O INR médio do sistema Coaguchek XS subestimou os valores obtidos em -0,01 pontos de INR, quando comparado ao método convencional, com erro padrão de 0,342. Valores acima de 3,5 mostraram resultados satisfatórios com coeficiente de correlação de 0,71, mas sem significância estatística (p>0,714).CONCLUSÕES: O sistema Coaguchek XS pode ser utilizado na monitorização do tempo de protrombina em pacientes com uso de anticoagulantes orais, desde que valores de INR acima de 3,5 sejam confirmados por meio de medidas realizadas em laboratório convencional.


tempo de protrombina, coagulação sanguínea, varfarina, tromboembolismo venoso


Kitchen S, Preston FE. Standardization of prothrombin time for laboratory control of oral anticoagulant therapy. Semin Thromb Haemost. 1999;25:17-26.

Hirsh J, Dalen JE, Anderson DR. Oral anticoagulants: mechanism of action, clinical effectiveness, and optimal therapeutic range. Chest. 1998;114(^sSuppl):445S-69.

Plesch W, Wolf T, Breitenbeck N. Results of the performance verification of the Coaguchek XS system. Thromb Res. 2008;123(2):381-9.

Connock M, Stevens C, Fry-Smith A, Jowett S, Fitzmaurice D, Moore D. Clinical effectiveness and cost-effectiveness of different models of managing long-term oral anticoagulation therapy: a systematic review and economic modeling. Health Technol Assess. 2007;11(38):iii-iv-ix-66.

Donaldson M, Sullivan J, Norbeck A. Comparison of international normalized ratios provided by two point-of-care devices and laboratory-based venipuncture in a pharmacist-managed anticoagulation clinic. Am J Health System Pharm. 2010;67(19):1616-22.

Williams VK, Griffiths AB. Acceptability of Coaguchek S and Coaguchek XS generated international normalized ratios against a laboratory standard in paediatric setting. Pathology. 2007;39(6):575-9.

Meneghelo ZM, Liporace IL, Nunes PP. Comparação dos níveis do tempo de protrombina, obtidos pelo monitor portátil CoaguChek XS e técnica padrão, em pacientes ambulatoriais usando anticoagulante oral. Instituto Dante Pazzanese de Cardiologia. 2009.

Coaguchek XS no monitoramento do INR em pacientes recebendo tratamento com varfarina. 2012.

De Piano LPA, Strunz CMC, Mansur ADP, Rached RA. Comparação entre os resultados do índice de normalização internacional medidos em dispositivo portátil (Hemochron Jr.) e por metodologia convencional. Arq Bras Cardiol. 2007;88(1):31-4.

Leiria TLL, Pellanda LC, Magalhães E, Lima GG. Controle do tempo de anticoagulação oral: correlação e concordância. Arq Bras Cardiol. 2007;89(1):1-5.

Bland JM, Altman DG. Measuring agreement in method comparison studies. Stat Methods Med Res. 1999;8(2):135-60.

Heneghan C, Alison W, Rafael P. The self-Monitoring Trialist Collaboration. Self-monitoring of oral anticoagulation: a systematic review and meta-analysis of individual patient data. Lancet. 2011.

David BM, Alan J, Rowena D. THINRS Trial: Effect of Home Testing of International Normalized Ratio on Clinical Events. New Engl J Med. 2010;363:17.

DeSantis G, Hogan-Schlientz J, Liska G. Real-world weekly INR Testing of 4,550 patients. 2012.

Anne H, Sam S, Daniel MW. Evidence-based management of anticoagulant therapy: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guideline. Chest. 2012;141:e152S-84S.

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