Validation of a weight-based nomogram for the use of intravenous heparin in transient ischemic attack or stroke

Abstract

Background and purpose: Intravenous heparin therapy is often used in patients presenting with transient ischemic attack (TIA) or stroke as either bridging therapy for anticoagulation with warfarin or primary therapy in suspected intracranial arterial dissection, crescendo TIAs, or suspected hypercoagulable states. We attempted to validate the use of a weight-based nomogram for heparin-adjusted therapy during hospital admission of patients with TIA or stroke.

Methods: A prospective, single-blinded, randomized, clinical trial was undertaken to compare the use of a specially designed, weight-based heparin nomogram against the traditional method of physician-ordered heparin therapy for patients admitted with TIA or stroke. The trial was not designed to examine the efficacy of heparin therapy but to examine the use of the nomogram for labor requirements, costs of monitoring, safety, length of heparin therapy, and user-friendliness.

Results: Pretreatment clinical factors were comparable between those randomized to use of the nomogram (n=101) and to usual care (n=105). Nomogram patients had a significantly lower first activated partial thromboplastin time than nonnomogram patients (60.6 +/- 16.8 versus 69.8 +/- 28.7 seconds). Patients treated by nomogram achieved a therapeutic range of anticoagulation sooner than nonnomogram patients (13.4 +/- 17.0 versus 17.9 +/- 14.1 hours). The fraction of time during which anticoagulation was therapeutic was significantly greater in patients on nomogram therapy (74 +/- 25% versus 67 +/- 26%). Nomogram patients also had significantly fewer supratherapeutic coagulation results, significantly fewer dose adjustment mistakes, significantly fewer calls to house staff regarding anticoagulation, and significantly fewer total complications than nonnomogram patients. The times required for discontinuation of heparin and discharge from hospital were not significantly different. A survey of house staff and nursing staff showed a preference for nomogram use.

Conclusions: The heparin nomogram is a user-friendly method of maintaining heparin infusions and is associated with improved anticoagulation measures, fewer total complications related to heparin therapy, fewer mistakes in heparin dosage adjustment, and decreased labor on the part of house staff and nursing staff.