NEW METHOD TO PREDICT PATIENTS INTRAVENOUS HEPARIN DOSE REQUIREMENTS

OBJECTIVE: To predict intravenous heparin dose requirements of patient s treated for thromboembolic disorders. DESIGN: A retrospective cohort study in which we used simple linear regression to predict patients' effective maintenance dose (EMD) of heparin (units/kg/hour needed to a chieve and maintain APTT therapeutic range) from patients' ''heparin r esponsiveness'' (the APTT increase after the initial 6 hours of hepari n treatment per units/kg/hour received). SETTING/PATIENTS: The model w as derived from 46 patients treated at one hospital (Hospital A) and t hen tested in 42 patients treated at another hospital (Hospital B). ME ASUREMENTS AND MAIN RESULTS: Among Hospital A patients, there was a st rong linear correlation (r = -.880: p < .001) between EMD (mean 16.02 units/kg/hour: 95% CI 14.9, 17.15) and ''heparin responsiveness'' (HR) : EMD = 25.651 - [95.118 x HR]. This model accurately predicted Hospit al B patients' EMD: 97% (37/38) fell within the model's 95% prediction interval; the mean absolute difference between predicted and actual E MD was 1.73 units/kg/hour (95% CI 1.39, 2.08); and only 16% of patient s had EMD's more than 3 units/kg/hour different from that predicted by the regression model. The model's accuracy was comparable to that of our gold standard, the weight-based heparin dosing nomogram. CONCLUSIO N: The infusion dose of intravenous heparin effective for an individua l patient can be predicted accurately from the patient's body weight a nd APTT response to the initial 6 hours of treatment, Especially in ho spitals where validated heparin dosing nomograms are not used, clinici ans may find this simple technique useful in achieving timely therapeu tic anticoagulation.