Retrospective Analysis of Heparin-Induced Thrombocytopenia Management at a Large Tertiary Hospital

Abstract

Background: Heparin-induced thrombocytopenia (HIT) is a disease that is difficult to quickly and accurately diagnose. The 4T score calculation is often used to determine the probability of HIT in order to guide further work-up and therapeutics. Our study aims to assess current practices regarding the diagnosis and management of HIT, particularly in reference to the appropriateness and cost of work-up and initiation of heparin alternatives based on the 4T score.

Methods: A retrospective chart review was carried out on patients at Scripps Mercy San Diego for whom work-up had been pursued with HIT antibody test and/or serotonin release assay between May 2011 and May 2012. For each of these patients a 4T score assessing the probability of HIT was carried out based on available chart information.

Results: Of the 218 work-ups reviewed, 74% had a low pre-test probability of HIT and 53% occurred in the medical intensive care unit (ICU). Only five of the 218 work-ups and one of the 116 ICU patient work-ups resulted in a diagnosis of HIT. The cost of using heparin alternatives in patients without a final diagnosis of HIT was approximately $100,750 and the cost of pursuing serologic work-up in patients with a low 4T score was $33,360. Average optical density (OD) scores among patients with a low and intermediate 4T score did not reach the threshold value for positivity with values of 0.257 and 0.334, respectively. Patients in the high 4T score group had average OD values of 1.68, which is 5 above the threshold for a positive result and the probability of HIT being present did not reach 50% until the OD was above 1.40.

Conclusions: This study demonstrates the significant costs associated with HIT diagnosis and management at a large hospital. Implementing a clinical decision support system to mitigate inappropriate ordering of serologic studies and initiation of heparin alternatives may be cost-saving. Further prospective studies will need to be undertaken to test this hypothesis.

J Hematol. 2014;3(2):27-33
doi: http://dx.doi.org/10.14740/jh157w