Gender imbalance and risk factor interactions in heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is caused by antibodies against a “self” protein—platelet factor 4—bound to heparin. We observed an overrepresentation of the female gender in 290 patients who developed HIT after cardiac or orthopedic surgery compared with the representation found in national...

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Bibliographic Details
Published in:Blood 2006-11, Vol.108 (9), p.2937-2941
Main Authors: Warkentin, Theodore E., Sheppard, Jo-Ann I., Sigouin, Christopher S., Kohlmann, Thomas, Eichler, Petra, Greinacher, Andreas
Format: Article
Language:English
Subjects:
Databases, Factual
Female
Heparin - adverse effects
Humans
Male
Randomized Controlled Trials as Topic
Regression Analysis
Risk Factors
Sex Characteristics
Surgical Procedures, Operative
Thrombocytopenia - chemically induced
Thrombocytopenia - epidemiology
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Summary:Heparin-induced thrombocytopenia (HIT) is caused by antibodies against a “self” protein—platelet factor 4—bound to heparin. We observed an overrepresentation of the female gender in 290 patients who developed HIT after cardiac or orthopedic surgery compared with the representation found in national databases (study 1). Therefore, we investigated gender imbalance in HIT by logistic regression analysis of a randomized controlled trial of unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) (study 2), and we analyzed individual patient data from 7 prospective studies comparing HIT frequency between UFH and LMWH, evaluating effects of gender, heparin (UFH vs LMWH), and patient type (surgical vs medical) (study 3). All 3 studies showed female overrepresentation, which for study 3 was a common odds ratio (OR) of 2.37 (95% confidence interval [95% CI], 1.37-4.09; P = .0015). Study 3 also showed an interaction between gender, heparin, and patient type. Although UFH was more likely than LMWH to cause HIT (P < .0001), this effect was predominantly seen in women compared with men (common OR, 9.22 vs 1.83; P = .020) and in surgical patients compared with medical patients (common OR, 13.93 vs 1.75; P = .005). We conclude that females are at greater risk for HIT and that using LMWH to prevent HIT may have greatest absolute benefit in females undergoing surgical thromboprophylaxis.
ISSN:0006-4971
1528-0020
DOI:10.1182/blood-2005-11-012450