Comparative effectiveness of low-molecular-weight heparin versus unfractionated heparin for thromboembolism...

Both unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) are approved for venous thromboembolism (VTE) prophylaxis. Which agent is superior remains controversial.

To compare the effectiveness, complications, and costs of UFH and LMWH as VTE prophylaxis for hospitalized medical patients.

Retrospective cohort.

Three hundred thirty-three acute care facilities in 2004-2005.

Adults with 4 common medical diagnoses considered to carry moderate-to-high risk of VTE. Excluded were patients on warfarin or with hospital stays of ≤ 2 days. VTE prophylaxis was assessed from billing data.

None.

VTE, major bleeding or heparin-induced thrombocytopenia, mortality, and cost.

Of 32,104 patients who received prophylaxis, 55% received LMWH and the remainder received UFH. The hospital where the patient obtained care was the strongest predictor of receiving LMWH. VTE was observed in 163 (0.51%) patients; complications, followed by stopping therapy, were rare (<0.2%). In analysis adjusted for the propensity for UFH and other covariates, patients treated with UFH had an odds ratio for VTE of 1.04 (95% confidence interval [CI] 0.76 to 1.43) compared to LMWH. In a grouped treatment model, the odds of VTE with UFH was 1.14 (95% CI 0.72 to 1.81). Adjusted odds of bleeding with UFH compared to LMWH were 1.64 (95% CI 0.50 to 5.33), adjusted odds of complications followed by stopping prophylaxis were 2.84 (95% CI 1.43 to 45.66), and adjusted cost ratio was 0.97 (95% CI 0.90 to 1.05).

For VTE prophylaxis, the effectiveness and cost of LMWH and UFH are similar, but LMWH is associated with fewer complications.