title: Risk factors for heparin-induced thrombocytopenia type II in aneurysmal subarachnoid hemorrhage.
abstract: BACKGROUND
  Heparin-induced thrombocytopenia type II (HIT II) correlates with a higher incidence of thromboembolic complications and unfavorable outcome.
  
  
  OBJECTIVE
  To examine the risk factors and outcomes for patients with HIT II with aneurysmal subarachnoid hemorrhage.
  
  
  METHODS
  Demographics, risk factors, treatments, and outcomes data of 600 aneurysmal subarachnoid hemorrhage patients admitted to the University of Illinois Medical Center in Chicago between June 2002 and July 2007 were retrospectively reviewed. Patients meeting the clinical criteria for HIT II were compared with those who did not develop thrombocytopenia.
  
  
  RESULTS
  Twenty-five patients (6%) met the clinical criteria for HIT II, and 396 (94%) did not develop thrombocytopenia. Both groups were the same with respect to age, Hunt-Hess score and Fisher grade on admission, medical conditions, and social risk factors. The HIT II patients had significantly more unfavorable outcomes (modified Rankin Scale score >3), deep vein thrombosis, stroke, pulmonary embolism, and death. Development of HIT II was strongly associated with symptomatic vasospasm (odds ratio, 5.7; 95% confidence interval, 2.5-13.1; P < .001) and number of angiographic procedures (odds ratio, 1.7; 95% confidence interval, 1.3-2.2; P < .001). Forward buildup selection modeling demonstrated the latter to be the strongest predictor for HIT II development (odds ratio, 2.3; 95% confidence interval, 1.7-3.2; P = .02).
  
  
  CONCLUSIONS
  Heparin-induced thrombocytopenia type II correlates with a worse outcome and higher risk of thromboembolic complications in aneurysmal subarachnoid hemorrhage patients. In addition, HIT II was strongly associated with the number of angiographic procedures performed during the same hospitalization.
authors.affiliation: University of Illinois at Chicago, College of Medicine, Department of Neurosurgery, Chicago, Illinois 60612-7329, USA. alaraj@uic.edu
authors.forename: Ali
authors.initials: A
authors.lastname: Alaraj
authors.forename: Adam
authors.initials: A
authors.lastname: Wallace
authors.forename: Navneet
authors.initials: N
authors.lastname: Mander
authors.forename: Victor
authors.initials: V
authors.lastname: Aletich
authors.forename: Fady T
authors.initials: FT
authors.lastname: Charbel
authors.forename: Sepideh
authors.initials: S
authors.lastname: Amin-Hanjani
mesh_terms: D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects*; D019457:Chromosome Breakage; D025063:Chromosome Disorders / Q000139:chemically induced* / Q000401:mortality; D005260:Female; D006493:Heparin / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000188:drug therapy* / Q000401:mortality; D013921:Thrombocytopenia / Q000139:chemically induced / Q000151:congenital* / Q000401:mortality; D016896:Treatment Outcome
chemical_list: D000925:Anticoagulants; D006493:Heparin