Symptomatic Venous Thromboembolism Rates After Hip Fracture Surgery in Patients Treated with Unfractionated Heparin, Enoxaparin, Dalteparin or Fondaparinux

Background:

Despite differences seen in clinical trials comparing alternatives for VTE prevention in orthopedics, these randomized studies (RCTs) have been criticized since they have focused mainly on venographic endpoints rather than clinical events. Additionally, the significance of venographically detected VTEs in the absence of clinical symptoms is unknown. We sought to determine if differences seen in RCTs translate into “real‐world” clinical outcomes.

Method:

We retrospectively analyzed inpatient data from over 500 hospitals in the United States. Patients admitted for hip fracture surgery between January 2003 and March 2005 were eligible for study inclusion. We compared subjects given either unfractionated heparin (UFH), enoxaparin, dalteparin or fondaparinux within 2 days of surgery. Patients were excluded if they were <18 yrs of age or if they had received more than one anticoagulant of interest during their hospitalization. The occurrence of VTE represented the primary endpoint and was determined by the presence of an ICD‐9 code for DVT or PE during the hospitalization. Logistic regression models were then used to assess differences in VTE rates between the anticoagulants, controlling for age, gender, severity of illness (Charlson), mechanical ventilation, length of stay, cancer diagnosis, presence of other hypercoaguable states, number of hospitalizations prior to index visit, and coumadin use.

Summary of Results:

A total of 45,574 patients were included in the analysis: fondaparinux = 2,378; dalteparin = 4,172; enoxaparin = 34,069; UFH = 4,955. The unadjusted VTE rates in each cohort were: fondaparinux = 0.3%, dalteparin = 0.8%, enoxaparin = 1.1%, UFH = 3.0%. After controlling for baseline covariates, patients on fondaparinux were least likely to experience a symptomatic VTE. The odds for VTE with each anticoagulant relative to fondaparinux were: dalteparin OR = 2.2, p = 0.04; enoxaparin OR = 3.2, p = 0.0012; UFH OR = 6.6, p < 0.0001.

Statement of Conclusions:

Anticoagulant choices for VTE prophylaxis result in different outcomes for patients. Fondaparinux use is associated with the lowest rates of VTE while patients receiving UFH face an increased risk for VTE.

Author Disclosure Block:

A. Shorr, GlaxoSmithKline Research grants, Speakers bureau; sanofi‐aventis Research grants, Speakers bureau; M. Sarnes, GlaxoSmithKline Consulting fees or other remuneration (payment); sanofi‐aventis Consulting fees or other remuneration (payment); Pfizer Consulting fees or other remuneration (payment); L. Happe, GlaxoSmithKline Consulting fees or other remuneration (payment); Sanofi‐Aventis Consulting fees or other remuneration (payment); Pfizer Consulting fees or other remuneration (payment); E. Farrelly, GlaxoSmithKline Consulting fees or other remuneration (payment); Sanofi‐Aventis Consulting fees or other remuneration (payment); Pfizer Consulting fees or other remuneration (payment); M. Higashi, GlaxoSmithkline Employment (full or part‐time).