The incidence of heparin-induced thrombocytopenia in hospitalized medical patients treated with subcutaneous unfractionated heparin: a prospective cohort study

Abstract

Although heparin-induced thrombocytopenia (HIT) is a known complication of intravenous unfractionated heparin (UFH), its incidence in medical patients treated with subcutaneous UFH is less well defined. To determine the incidence of HIT in this category of patients, the platelet count was performed at baseline and then every 3 ؎ 1 days in 598 consecutive patients admitted to 2 medical wards and treated with subcutaneous UFH for prophylactic (n ‫؍‬ 360) or therapeutic (n ‫؍‬ 238) indications. The diagnosis of HIT was accepted in the case of a platelet drop of 50% or more and either the demonstration of heparin-dependent antibodies or (when this search could not be performed) the combination of the following features: (1) the absence of any other obvious clinical explanation for thrombocytopenia, (2) the occurrence of thrombocytopenia at least 5 days after heparin start, and (3) either the normalization of the platelet count within 10 days after heparin discontinuation or the earlier patient's death due to an unexpected thromboembolic complication. HIT developed in 5 patients (0.8%; 95% CI, 0.1%-1.6%); all of them belonged to the subgroup of patients who received heparin for prophylactic indications. The prevalence of thromboembolic complications in patients with HIT (60%) was remarkably higher than that observed in the remaining 593 patients (3.5%), leading to an odds ratio of 40.8 (95% CI, 5.2-162.8). Although the frequency of HIT in hospitalized medical patients treated with subcutaneous heparin is lower than that observed in other clinical settings, this complication is associated with a similarly high rate of thromboembolic events.

Venous thromboembolism prevention in the acutely ill medical patient: A review of the literature and focus on special patient populations

“…Enoxaparin, 40 mg, once daily would result in the same eight VTE events being avoided, and the cost would be only 1-2 patients developing a major bleed or HIT. In this regard, it is possible that the more convenient and safer agents such as LMWH or fondaparinux, which have higher drug costs compared to UFH, are less expensive in the overall provision of healthcare [3,40,42].…”

Relationship between the 4Ts scoring system and the antiplatelet factor 4/heparin antibodies test in critically ill patients

“…In line with previous reports that the etiology of thrombocytopenia is multifactorial, 1,2 there were still many patients for whom we could not fully explain their etiologies. However, the reported prevalence of HIT is extremely low, less than 0.2-5% in patients receiving heparin 16,27,28 and less than 0.5% in ICU patients, 4,12,19,29 and it should be noted that the negative predictive value of a diagnostic test is higher when the prevalence of the target disease in the population to be tested is lower. 30 The positive predictive value of the 4Ts score was as low as 15.4%, a value less than the previously reported range from 21.4% to 100%.…”

“…We diagnosed HIT in all patients by both PF4/heparin Ab and the normalization of the platelet count within 10 days after heparin discontinuation. 16 The Institutional Review Board at Chiba University approved the study.…”

“…Suspicion of HIT was determined by the attending critical care physician based on the following criteria: (i) development of thrombocytopenia (i.e., a drop in platelet count) or thrombosis after heparin administration, (ii) the absence of any other obvious clinical explanation for thrombocytopenia. 16 In all patients with suspected HIT, a PF4/heparin Ab test was carried out for serological diagnosis with immediate discontinuation of heparin and commencement of argatroban, an antithrombin agent. We diagnosed HIT in all patients by both PF4/heparin Ab and the normalization of the platelet count within 10 days after heparin discontinuation.…”

Effectiveness of a clinical decision support system to identify heparin induced thrombocytopenia

“…The incidence of HIT ranges from 1-3% depending on the type of heparin product and patient population [2,3]. Criteria for the diagnosis of HIT in patients treated with heparin products include either a significant proportional platelet count decrease (for example, a 50% decrease from maximum value), or a decrease below a specified threshold (for example, 150,000 platelets/mm 3 ) [4][5].…”