title: 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.
authors.affiliation: Division of Internal Medicine, Department of Medical and Surgical Sciences, 2nd Chair of Internal Medicine, University Hospital of Padua, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Girolami
authors.forename: Paolo
authors.initials: P
authors.lastname: Prandoni
authors.forename: Piero M
authors.initials: PM
authors.lastname: Stefani
authors.forename: Cinzia
authors.initials: C
authors.lastname: Tanduo
authors.forename: Paola
authors.initials: P
authors.lastname: Sabbion
authors.forename: Petra
authors.initials: P
authors.lastname: Eichler
authors.forename: Roberto
authors.initials: R
authors.lastname: Ramon
authors.forename: Giovannella
authors.initials: G
authors.lastname: Baggio
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Fabris
authors.forename: Antonio
authors.initials: A
authors.lastname: Girolami
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D001327:Autoimmune Diseases / Q000139:chemically induced / Q000453:epidemiology* / Q000276:immunology; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology; D006748:Hospital Departments / Q000706:statistics & numerical data; D006785:Hospitals, University / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007279:Injections, Subcutaneous; D007297:Inpatients; D007388:Internal Medicine; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010978:Platelet Factor 4 / Q000276:immunology / Q000378:metabolism; D015995:Prevalence; D011446:Prospective Studies; D013921:Thrombocytopenia / Q000139:chemically induced / Q000453:epidemiology* / Q000276:immunology; D013923:Thromboembolism / Q000453:epidemiology / Q000517:prevention & control
chemical_list: D000925:Anticoagulants; D010978:Platelet Factor 4; D006493:Heparin