Bivalirudin is a direct thrombin inhibitor used for therapeutic anticoagulation in patients with suspected or confirmed heparin induced thrombocytopenia. Dosing recommendations for bivalirudin are variable in published literature which results in dosing discontinuity.
Identifying patient characteristics associated with bivalirudin dose requirements was the primary objective. Secondary objectives were to assess time to therapeutic activated partial thromboplastin time (APTT) for patients on bivalirudin therapy and identify the mean bivalirudin dose achieving therapeutic anticoagulation.
The retrospective review included hospitalized patients?18 years old with?24 hours of bivalirudin therapy indicated for therapeutic anticoagulation between January 1, 2010 and October 31, 2011. Patients with bivalirudin therapy indicated for percutaneous coronary intervention, lower extremity bypass, venous thromboembolism prophylaxis, or patients with no documented APTT goal were excluded.
Of the 87 patients included in the study, the median bivalirudin dose to achieve goal APTT was 0.037 mg/kg/hr. Creatinine clearance (CrCl) was the only characteristic associated with bivalirudin dose requirements (p=0.0271, r2=0.066). The mean bivalirudin dose required to achieve goal APTT based on renal function was 0.023 mg/kg/hr for patients with CrCl < 30 mL/min or dialysis requirements, 0.038 mg/kg/hr for patients with CrCl between 30-60 mL/min, 0.061 mg/kg/hr for patients with CrCl between 61-90 mL/min, and 0.069 mg/kg/hr for patients with CrCl > 90 mL/min (p=0.026). Goal APTT was obtained in a mean of 32.6 hours. Increased bivalirudin dose requirements (p=0.002, r2=0.123), infrequent APTT monitoring (p=< 0.001, r2=0.258), and infrequent bivalirudin dose adjustments (p=0.0189, r2=0.076) were associated with an increased time to therapeutic APTT.
Patients with decreased renal function required decreased bivalirudin doses to achieve goal APTT. No other patient characteristics influenced bivalirudin dosing. Factors associated with longer time to goal APTT included increased bivalirudin doses required to achieve goal APTT, infrequent APTT monitoring, and infrequent bivalirudin dose changes.