How one academic medical center has managed potency changes with unfractionated heparin

The United States Pharmacopeia recently changed the standards for unfractionated heparin (UFH) resulting in reduction in potency by about 10 %. Despite the reduction in potency, no new recommendations for UFH dosing were recommended. A retrospective review was conducted on patients receiving UFH and at least one activated partial thromboplastin time (aPTT) after start of infusion. Patients receiving UFH prior to April 2010 were collected as old UFH potency patients versus those receiving UFH after May 1st, 2010 were defined as new UFH potency patients. The primary endpoint was time to a therapeutic aPTT. Secondary endpoints included the number venous thrombotic events (VTE) and bleeding events during hospitalization through 30 days post discharge. Thrombotic events were defined as acute coronary syndrome, ischemic stroke, and VTE. Bleeding was defined in accordance with the GUSTO bleeding scale. A total of 359 patients were included for evaluation, 181 in the old UFH group and 178 in the new UFH group. The primary endpoint was similar between groups with an average time of 18.8 ± 25.4 versus 20.8 ± 22.2 h in the old and new UFH groups respectively (p = 0.092). Patients receiving old UFH and an initial bolus had higher aPTTs (96.6 ± 43.7 s) than those receiving new UFH and an initial bolus (76.7 ± 34.5 s) (p = 0.003). There was no difference found between groups in regards to bleeding or thrombotic events during hospitalization or through 30 days. In patients receiving UFH, dosed per the institutions' nomogram, no clinically significant outcomes were found between the old and new UFH potencies.