Enoxaparin dosing in the elderly using adjusted body weight

We prospectively compared anti-Xa activity in 61 elderly (> 65 years) subjects receiving enoxaparin according to standard or adjusted body weight (ABW) dosing. In the ABW dosing group, mean patient age was 76 years, mean weight 80 kg, mean serum creatinine 1.0 mg/dl, and mean CrCl 48 ml/min. ABW dosing resulted in 57% of elderly study subjects achieving anti-Xa activity of 0.5-1.0 IU/ml, and 80% achieving anti-Xa activity of 0.5-1.2 IU/ml. Compared to standard dosing, for all subjects ABW dosing of enoxaparin was associated with a more favorable mean anti-Xa activity (0.98 IU/ml vs. 1.28 IU/ml, P = 0.001), fewer highest-risk (> 1.5 IU/ml) supratherapeutic anti-Xa levels (0% vs. 28%, P = 0.001), and more frequent therapeutic levels among women (64% vs. 25%, P = 0.001). ABW dosing of enoxaparin may be beneficial in elderly patients aged 65 and older, and its benefit appears to be more pronounced in female patients.