Safety and efficacy of unfractionated heparin versus enoxaparin in patients who are obese and patients with severe renal impairment: analysis from the ESSENCE and TIMI 11B studies

Background The advantages of enoxaparin over unfractionated heparin (UFH) for the treatment of patients with non-ST-segment elevation acute coronary syndromes are well established. However, no data are available about the safety and efficacy in patients who are obese and patients with severe renal impairment. Methods A retrospective analysis of treatment effects was performed on patients who were obese and patients with severe renal impairment from the Efficacy Safety Subcutaenous Enoxaparin in Non-Q-wave Coronary Events (ESSENCE) and Thrombolysis in Myocardial Infarction (TIMI) 11B trials, in which patients were treated with enoxaparin or UFH. The primary composite end point was death, myocardial infarction (MI), and urgent revascularization (UR), and the secondary end points were major and any hemorrhage. Results When compared with UFH, enoxaparin reduced the rate of the primary end point in patients who were obese (14.3% vs 18.0%, P = .05), patients who were not obese (16.1% vs 19.2%, P <.01), and patients without severe renal impairment (15.7% vs 18.4%, P <.01). There was no significant difference in major bleeding between enoxaparin and UFH in any of the 4 subgroups. There were no differences in either the primary end point (17.6% vs 16.2%, P = .39) or major hemorrhage (1.3% vs 0.8%, P = .12) in patients who were obese receiving either UFH or enoxaparin compared with patients who were not obese. Patients with severe renal impairment tended toward a higher rate of the primary end point (25.9% vs 17%, P = .09) and experienced more major hemorrhages (6.6% vs 1.1%, P <.0001). Conclusions Enoxaparin reduced the rate of the combined end point of death/MI/UR in the subgroups of patients who were obese, patients who were not obese, and patients without renal insufficiency. Obesity did not impact clinical outcomes in the combined analysis of ESSENCE and TIMI 11B. Patients with severe renal impairment have a higher risk of clinical events and major and any hemorrhages than patients without severe renal impairment, whether they are treated with UFH or enoxaparin.