Early Management of Heparin-Induced Thrombocytopenia Using a Simple Scoring System

Abstract 4679

Since stopping heparin therapy lessens the probability of severe complications of heparin-induced thrombocytopenia (HIT) such as arterial and venous thromboembolism, it is important to stop heparin as soon as the diagnosis is suspected. As HIT is a complex disorder and its diagnosis is difficult, the use of a clinical scoring system would facilitate clinical decision making. One of the foremost issues in these patients is whether to discontinue heparin (to avoid HIT complications) or not (to avoid thrombotic complications). This study was performed to develop a simple scoring system to aid in the early clinical management of suspected HIT patients with regard to decisions for continued heparin therapy. The system was designed to arrive at low (0) or possible (1) probability scores based on clinical criteria without knowledge of lab test results, except platelet counts, to avoid delays. As the safest clinical approach is to discontinue heparin, intermediate and high scores were combined. Historically, laboratory tests such as the heparin-induced platelet aggregation test (PA) and ¹⁴C-serotonin release assay (SRA) and nonfunctional tests such as the enzyme-linked-immunosorbent assay (ELISA) have been used for the diagnosis of HIT. These test results are frequently available only after 12 to 36 hours which, for some patients, is a risk due to continued heparin therapy while waiting for test results. One solution to this problem is to have a clinical scoring system to guide the clinician before test results are available. This study enrolled 100 critically ill VA hospitalized patients with a >=30% fall in platelet count. Assessment of platelet aggregation (PA), ¹⁴C-SRA and GTI ELISA was also performed. In this population 53% were scored 1 and of these 43% were positive by lab testing for HIT. Emphasizing the decision to discontinue heparin, the clinical signs of HIT were paramount for the immediate determination of a diagnosis of HIT. Specifically, this study demonstrated the value of a simple clinical score to aid in the clinical management decision making to continue or discontinue heparin in patients suspected of having HIT, without dependence on a positive HIT lab test. An algorithm is provided. This scoring system does not preclude reassessment of patients in terms of continuing heparin if subsequent laboratory tests and/or thrombosis become positive.