Evaluation of an argatroban nomogram for heparin-induced thrombocytopenia

Objectives: To evaluate clinical and laboratory outcomes of an argatroban nomogram in patients with confirmed or suspected heparin-induced thrombocytopenia (HIT).

Methods: A retrospective cohort study was conducted at a large tertiary teaching hospital comparing patients treated according to an argatroban nomogram versus control. The control arm consisted of patients treated without a nomogram-based approach. Primary efficacy outcomes were the percentage of patients with therapeutic, supratherapeutic and subtherapeutic activated partial thromboplastin times at predetermined time intervals. Additional outcome measures were median time to stabilization and number of dose adjustments in each group. The incidence of thrombotic events, major and minor bleeding were also assessed. A subgroup analysis of critically-ill patients and those receiving fondaparinux was conducted.

Results: Forty-nine patients were included, 31 in the nomogram and 18 in the control group. At 24 hours, fewer patients in the nomogram group were supratherapeutic, 3 (10%) vs 5 (36%), p=0.04. Median time to dose stabilization was 8 hours in the nomogram group vs 6 hours in the control group, p=0.33. The total number of dose adjustments in the nomogram vs control groups were 1.4 vs 0.4 respectively, p=0.02. No significant difference was observed in thrombotic or bleeding events between the nomogram vs control groups, thrombotic events 2 vs 0, p=0.12; major bleeding 1 vs 2, p=0.28; minor bleeding 4 vs 2, p=0.66, respectively. In the subgroup analysis of critically-ill patients, 2 (10%) vs 4 (44%) were supratherapeutic at 24 hr in the nomogram vs control groups respectively, p=0.005. The average fondaparinux to warfarin overlap was 2.6 days. No bleeding or thrombotic events were documented while on fondaparinux. 

Conclusion: The implementation of an argatroban nomogram proved to be safe and effective, providing an effective tool for dosing and monitoring patients with HIT.