Clinical outcomes in a cohort of patients with heparin-induced thrombocytopenia

Am J Hematol. 2017 Aug;92(8):730-738. doi: 10.1002/ajh.24759. Epub 2017 Apr 26.

Abstract

Background: Heparin-induced thrombocytopenia (HIT) is a thrombotic disorder usually prompting treatment with non-heparin anticoagulants. The benefits and risks of such treatments have not been fully assessed.

Methods: We analyzed data for 442 patients having a positive heparin-platelet factor 4 antibody test and recent heparin exposure. The primary outcome was a composite endpoint (death, limb amputation/gangrene, or new thrombosis). Secondary outcomes included bleeding and the effect of anticoagulation.

Findings: Seventy-one patients (16%) had HIT with thrombosis (HIT-T); 284 (64%) had HIT without thrombosis (isolated HIT); 87 (20%) did not have HIT. An intermediate or high "4T" score was found in 85%, 58%, and 8% of the three respective groups. Non-heparin anticoagulation was begun in 80%, 56%, and 45%. The composite endpoint occurred in 48%, 36%, and 17% (P = .01) of which 61%, 38%, and 40% were receiving non-heparin anticoagulation. Compared with the no HIT group, the composite endpoint was significantly more likely in HIT-T [HR 2.48 (1.35-4.55), P = .003)] and marginally more likely in isolated HIT [HR 1.66 (0.96-2.85), P = .071]. Importantly, risk increased (HR 1.77, P = .02) after platelet transfusion. Major bleeding occurred in 48%, 36%, and 16% of the three groups (P = .005). Non-heparin anticoagulation was not associated with a reduction in composite endpoint events in either HIT group.

Interpretation: HIT patients have high risks of death, limb amputation/gangrene, thrombosis, and bleeding. Non-heparin anticoagulant treatment may not benefit all patients and should be considered only after careful assessment of the relative risks of thrombosis and bleeding in individual patients.

MeSH terms

  • Adult
  • Aged
  • Anticoagulants / therapeutic use
  • Autoantibodies / blood
  • Autoantibodies / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Heparin / adverse effects*
  • Heparin / immunology
  • Humans
  • Male
  • Middle Aged
  • Mortality
  • Patient Outcome Assessment
  • Platelet Count
  • Platelet Factor 4 / immunology
  • Proportional Hazards Models
  • Retrospective Studies
  • Thrombocytopenia / diagnosis
  • Thrombocytopenia / epidemiology*
  • Thrombocytopenia / etiology*
  • Thrombocytopenia / therapy

Substances

  • Anticoagulants
  • Autoantibodies
  • Platelet Factor 4
  • Heparin