Utilization and effectiveness of a weight-based heparin nomogram at a large academic medical center

Abstract

Objective: To determine the utilization rate of a weight-based heparin nomogram and to assess the performance of the nomogram outside of experimental conditions.

Study design: Prospective cohort analysis.

Patients and methods: A total of 747 consecutive patients treated with intravenous heparin therapy for any indication on an internal medicine service were evaluated for the utilization rate of the weight-based nomogram, the time needed to exceed heparin's therapeutic threshold (activated partial thromboplastin time [aPTT] of > 1.5 times the control value), and the time needed to achieve heparin's therapeutic range (aPTT of 1.5 to 2.4 times the control value). Physicians were encouraged to use the weight-based nomogram by using conventional continuing medical education techniques and by configuring the computerized order entry system to give physicians an equally easy and voluntary choice between choosing the weight-based nomogram or ordering heparin in the traditional fashion.

Results: The study program had no effect in increasing the utilization rate of the nomogram; this rate remained the same as before the program was initiated (10%). Less time was needed both to exceed the therapeutic threshold and to achieve a therapeutic range with the weight-based nomogram compared with physician-guided dosing (P < .001 and P = .021, respectively). No difference was demonstrated between the weight-based and physician-guided groups in incidence of bleeding complications or in the proportion of patients with one or more supratherapeutic aPTTs.

Conclusions: The weight-based nomogram led to superior intermediate outcomes compared with physician-guided dosing. However, despite efforts intended to modify physician behavior, the utilization rate remained so low that it was ineffective. Further research into the reasons why physicians chose not to use the weight-based nomogram and further research into methods to translate efficacious therapies into effective patient care are indicated.