Assessing the impact of a heparin-induced thrombocytopenia protocol on patient management, outcomes and cost

Summary

Establishing the diagnosis of heparin induced thrombocytopenia (HIT) is challenging as laboratory tests for HIT vary in specificity and availability. As HIT suspicion far exceeds confirmation of diagnosis, overtreatment is an emerging concern. This pilot study evaluated the impact of a HIT Recognition and Management Protocol on direct thrombin inhibitor (DTI) prescribing, outcomes, and cost. The primary endpoint was DTI cessation within 12 hours of receipt of negative HIT serology. An observational cohort study using a pre-post design was performed. Sixty-one patients were in the pre-period (before implementation) and 46 in the post-period (after implementation). DTI therapy was discontinued within 12 hours of negative serology in 19.4% of pre-period patients compared to 40% of post-period patients, p=.058. DTI therapy was discontinued within 24 hours of receipt of a negative PF4/heparin ELISA more often in the post-period ; 7/23 (30.4%) pre-period patients versus 16/26 (61.5%) post-period patients, p <0.05. Protocol implementation resulted in a significant improvement in timely initiation of DTI therapy (within 12 hours of HIT antibody testing) in those with a moderate to high suspicion of HIT; 8/31 (25.8%) of pre-period patients versus 24/31 (77.4%) of post-period patients, p <0.0001. Thrombotic events occurred in significantly more patients in the pre-period as compared to the post-period; 21/61 (34.4%) versus 6/46 (13%), respectively, p = 0.01. Major bleeding was reduced by 6.6 % after protocol implementation. The projected annual cost savings from decreased inappropriate DTI use was over $450,000. Protocol implementation had a positive impact on DTI prescribing, outcomes and cost.

Keywords

HIT protocol - direct antithrombin agents

• References

• 1 Greinacher A, Althaus K, Krauel K. et al. Heparin-induced thrombocytopenia. Hamostaseologie 2010; 30: 17-28.
• 2 Linkins L, Dans AL, Moores LK. et al. Treatment and prevention of heparin-induced thrombocytopenia: Antithrombotic therapy and prevention of thrombosis, 9^th ed: American College of Chest Physicians Evidenced-Based Clinical Practice Guidelines. Chest 2012; 141: e495S-e530S.
• 3 Warkentin TE, Greinacher A, Gruel Y. et al. Laboratory testing for heparin-induced thrombocytopenia: a conceptual framework and implications for diagnosis. J Thromb Haemost 2011; 9: 2498-2500.
• 4 Warkentin TE. How I diagnose and manage HIT. Hematology Am Soc Hematol Educ Program 2011; 2011: 143-149.
• 5 Lo GK, Sigouin CS, Warkentin TE. What is the potential for overdiagnosis of heparin-induced thrombocytopenia?. Am J Hematol 2007; 82: 1037-1043.
• 6 Warkentin TE, Sheppard JI, Moore JC. Quantitative interpretation of optical density measurements using PF4-dependent enzyme-immunoassays. J Thromb Haemost 2008; 6: 1304-1312.
• 7 Cuker A. Heparin-induced thrombocytopenia (HIT) in 2011: An epidemic of overdiagnosis. Thromb Haemst 2011; 106: 993-994.
• 8 Lo GK, Juhl D, Warkentin TE. et al. Evaluation of pretest clinical score (4 T_s) for the diagnosis of heparin induced thrombocytopenia in two clinical settings. J Thromb Haemost 2006; 4: 759-765.
• 9 Smythe MA, Koerber JM, Forsyth LL. et al. Argatroban dose requirements and outcomes in intensive care versus non-intensive care patients. Pharmacother 2009; 29: 1073-1081.
• 10 Warkentin TE, Greinacher A, Koster A. et al. Treatment and prevention of heparin-induced thrombocytopenia. American College of Chest Physicians evidence-based clinical practice guidelines (8^th edition). Chest 2008; (Suppl. 06) 340S-380S.
• 11 Smythe MA, Mehta TP, Koerber JM. et al. Development and implementation of a comprehensive heparin-induced thrombocytopenia recognition and management protocol. Am J Health-Syst Pharm 2012; 69: 241-248.
• 12 Cuker A, Arepally G, Crowther MA. et al. The HIT Expert Probability (HEP) Score: a novel pre-test probability model for heparin-induced thrombocytopenia based upon expert opinion. J Thromb Haemost 2010; 8: 2642-2650.
• 13 Cuker A. Heparin-induced thrombocytopenia: past, present and future. J Thromb Thrombolysis 2011; 31: 353-366.
• 14 Otis SA, Zehnder JL. Heparin induced thrombocytopenia: current status and diagnostic challenges. Am J Hematol 2010; 85: 700-706.
• 15 Arepally GM, Ortel TL. Heparin-induced thrombocytopenia. N Engl J Med 2006; 355: 809-817.
• 16 Kiser TH, Mann AM, Trujillo TC. Evaluation of empiric versus nomogram based direct thrombin inhibitor management in patients with suspected heparin induced thrombocytopenia. Am J Hematol 2011; 86: 267-272.
• 17 Ruf KM, Bensadoun ES, Davis GA. et al. A clinical-laboratory algorithm incorporating optical density value to predict heparin-induced thrombocytopenia. Thromb Haemost 2011; 105: 553-559.