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 extended 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 was higher in women compared with men (P < .001) and in nonsmokers compared with smokers (< .001) in multiple regression analysis. Also, during the fixed-dose treatment (n = 131) an independent relation between anti-Xa activity 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 consider the influence of sex and smoking habits. (Am Heart J 1999;137:72-8.)