Paul A Arpino1, Zareh Demirjian, Elizabeth M Van Cott. 1. Department of Pharmacy, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA. parpino@partners.org
Abstract
STUDY OBJECTIVE: To determine the clinical utility of the chromogenic factor X level for conversion from argatroban to warfarin in hospitalized patients. DESIGN: Prospective observational study. PATIENTS: Sixty-two hospitalized patients with indications for anticoagulation in whom the chromogenic factor X assay was used for conversion from argatroban to warfarin. SETTING: University-affiliated hospital. INTERVENTION: From December 2003-May 2004, data for all patients in whom the chromogenic factor X assay was used for conversion from argatroban to warfarin were screened for inclusion. When the chromogenic factor X level was satisfactory, the clinician discontinued the argatroban and a confirmatory international normalized ratio (INR) was obtained. MEASUREMENTS AND MAIN RESULTS: To determine the ability of the chromogenic factor X level to predict the INR free of argatroban influence, we calculated the sensitivity and specificity by using a cutoff chromogenic factor X level of 45% or less, or greater than 45%, which corresponded to an INR of 2 or greater, or less than 2, respectively. We constructed a receiver operating characteristic curve to illustrate various cutoff levels of chromogenic factor X. Of 146 patients screened, 62 had data that met criteria for analysis. An average of 6 +/- 3 doses of warfarin were administered before the confirmatory coagulation studies were obtained. The average time from the chromogenic factor X measurement to obtainment of confirmatory coagulation studies was 9 +/- 4 hours. Use of a chromogenic factor X level of 45% or less to predict an INR of 2 or greater absent of argatroban influence had a sensitivity of 93%, a specificity of 78%, and an accuracy of 89%. The area under the receiver operating characteristic curve was 0.91 (95% confidence interval 0.81-0.99, p<0.0001). CONCLUSION: The chromogenic factor X level is an accurate alternative when converting hospitalized patients from argatroban to warfarin. A chromogenic factor X level of 45% or less is a reliable predictor that the INR will be therapeutic when argatroban therapy is discontinued.
STUDY OBJECTIVE: To determine the clinical utility of the chromogenic factor X level for conversion from argatroban to warfarin in hospitalized patients. DESIGN: Prospective observational study. PATIENTS: Sixty-two hospitalized patients with indications for anticoagulation in whom the chromogenic factor X assay was used for conversion from argatroban to warfarin. SETTING: University-affiliated hospital. INTERVENTION: From December 2003-May 2004, data for all patients in whom the chromogenic factor X assay was used for conversion from argatroban to warfarin were screened for inclusion. When the chromogenic factor X level was satisfactory, the clinician discontinued the argatroban and a confirmatory international normalized ratio (INR) was obtained. MEASUREMENTS AND MAIN RESULTS: To determine the ability of the chromogenic factor X level to predict the INR free of argatroban influence, we calculated the sensitivity and specificity by using a cutoff chromogenic factor X level of 45% or less, or greater than 45%, which corresponded to an INR of 2 or greater, or less than 2, respectively. We constructed a receiver operating characteristic curve to illustrate various cutoff levels of chromogenic factor X. Of 146 patients screened, 62 had data that met criteria for analysis. An average of 6 +/- 3 doses of warfarin were administered before the confirmatory coagulation studies were obtained. The average time from the chromogenic factor X measurement to obtainment of confirmatory coagulation studies was 9 +/- 4 hours. Use of a chromogenic factor X level of 45% or less to predict an INR of 2 or greater absent of argatroban influence had a sensitivity of 93%, a specificity of 78%, and an accuracy of 89%. The area under the receiver operating characteristic curve was 0.91 (95% confidence interval 0.81-0.99, p<0.0001). CONCLUSION: The chromogenic factor X level is an accurate alternative when converting hospitalized patients from argatroban to warfarin. A chromogenic factor X level of 45% or less is a reliable predictor that the INR will be therapeutic when argatroban therapy is discontinued.
Authors: Michael B Streiff; Paula L Bockenstedt; Spero R Cataland; Carolyn Chesney; Charles Eby; John Fanikos; Patrick F Fogarty; Shuwei Gao; Julio Garcia-Aguilar; Samuel Z Goldhaber; Hani Hassoun; Paul Hendrie; Bjorn Holmstrom; Kimberly A Jones; Nicole Kuderer; Jason T Lee; Michael M Millenson; Anne T Neff; Thomas L Ortel; Judy L Smith; Gary C Yee; Anaadriana Zakarija Journal: J Natl Compr Canc Netw Date: 2011-07-01 Impact factor: 11.908