title: Heparin-platelet factor 4 antibodies in intensive care patients: an observational seroprevalence study.
abstract: Heparin-platelet factor 4 (PF4) antibodies mediate heparin-induced thrombocytopenia (HIT) and, irrespective of thrombocytopenia, are associated with poorer outcomes in some patients. The prevalence of heparin-PF4 antibodies, including platelet-activating ones, in patients in the medical, neurotrauma, or shock-trauma intensive care unit (ICU) remains unclear. In this single-center, observational study, heparin-PF4 antibodies (IgG/A/M) were measured by ELISA in 185 adults (median APACHE II score, 16) admitted to the medical (n = 27), neurotrauma (n = 96), or shock-trauma (n = 62) ICU and after 7 +/- 2 days. Seropositive patients and heparin-treated patients with unexplained, new-onset thrombocytopenia were also tested for platelet-activating antibodies using a serotonin release assay (SRA). Of 185 patients, seropositivity occurred in 20 patients (10.8%; 95% CI 6.7-16.2%) at admission and 54 (29.2%, 95% CI 22.8-36.3%) after 7 days (P < 0.001). Platelet-activating antibodies occurred in 4 seropositive patients at admission and 9 seropositive patients after 7 days (including in 1 patient at each assessment), each without thrombocytopenia or new thrombosis. Of 12 seropositive patients with platelet-activating antibodies, 6 had an ELISA optical density (OD) >1.0. ELISA-positive, SRA-negative, suspected HIT occurred in 1 patient. Heparin-PF4 antibodies are present in 10.8% of medical, neurotrauma, or shock-trauma ICU patients at admission and increase significantly to 29.2% within 7 days. Approximately 17-20% of seropositive ICU patients, often those with an ELISA OD >1.0, have platelet-activating heparin-PF4 antibodies.
authors.affiliation: Emergency Medicine, The University of Texas Medical School at Houston, Houston, TX, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Levine
authors.forename: Georgene W
authors.initials: GW
authors.lastname: Hergenroeder
authors.forename: John L
authors.initials: JL
authors.lastname: Francis
authors.forename: Charles C
authors.initials: CC
authors.lastname: Miller
authors.forename: Marcie J
authors.initials: MJ
authors.lastname: Hursting
mesh_terms: D018806:APACHE; D000906:Antibodies / Q000097:blood*; D000925:Anticoagulants / Q000276:immunology*; D003422:Critical Care; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006493:Heparin / Q000276:immunology*; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000276:immunology; D010978:Platelet Factor 4 / Q000276:immunology*; D011446:Prospective Studies; D016036:Seroepidemiologic Studies; D013781:Texas / Q000453:epidemiology; D013921:Thrombocytopenia / Q000097:blood / Q000453:epidemiology / Q000276:immunology* / Q000401:mortality; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000906:Antibodies; D000925:Anticoagulants; D010978:Platelet Factor 4; D006493:Heparin