Unfractionated heparin may cause higher surgical risks for women

Women undergoing surgery who are treated with unfractionated heparin have a high incidence of heparin-induced thrombocytopenia (HIT), according to a report in the Nov. 1 issue of Blood. The risk from low-molecular-weight heparin is minimal, regardless of treatment setting.

Theodore E. Warkentin, MD, of McMaster University in Hamilton, Ontario, Canada, and colleagues noticed a high incidence of HIT in women after cardiac or orthopedic surgery, according to national databases. In this study, they set out to examine the link more closely using prospective studies comparing unfractionated heparin with low-molecular-weight heparin (LMWH).

Three separate studies showed overrepresentation of women with HIT. Analysis of the data showed that HIT was more likely to occur in women than men (common OR, 2.37) and in surgical versus medical patients (common OR, 3.25). Unfractionated heparin was also much more likely to cause HIT than LMWH in women versus men (common OR, 9.22 vs. 1.83) and in surgical versus medical patients (common OR, 13.93 vs. 1.75).

Warkentin TE, Sheppard JI, Sigouin CS, et al. Gender imbalance and risk factor interactions in heparin-induced thrombocytopenia. Blood. 2006;108:2937-2941.