Influences of sex and smoking habits on anticoagulant activity in low-molecular-weight heparin treatment of unstable coronary artery disease

Background In the FRISC trial, dalteparin 120 IU/kg body weight twice daily for unstable coronary artery disease was safe and reduced the risk of new coronary events. This risk reduction was maintained during the following ex tended treatment with a fixed dose of 7500 IU dalteparin once daily. Methods and results Minor bleeding was more frequent in women compared with men: relative risk (CI) 2.88 (1.78 to 4.67) during the weight-adjusted and 2.36 (1.37 to 2.63) during the fixed dose treatment. The anti-Xa activity determined in samples (n = 175) obtained during the acute phase treatment w as higher in women compared with men (P < .001) and in nonsmokers compared with smokers (< .001) in multiple regression analysis. Also, during the fix ed-dose treatment (n = 131) an independent relation between anti-Xa activit y and sex (P < .001), but not smoking habits, persisted. Conclusion To improve future low-molecular-weight heparin dose regimens for the treatment of acute coronary syndromes, it might be important to consid er the influence of sex and smoking habits.