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No Difference in Risk for Thrombocytopenia During Treatment of Pulmonary Embolism and Deep Venous Thrombosis With Either Low-Molecular-Weight Heparin or Unfractionated Heparin^*

A Metaanalysis

^* From the Division of Pulmonary and Critical Care Medicine (Drs. Morris and Castrejon), and Division of Biostatistics (Dr. Gamst), Department of Family and Preventative Medicine, University of California, San Diego; and Kaiser Permanente (Dr. Devendra), Sacramento, CA.

Correspondence to: Timothy A. Morris, MD, Professor of Medicine, UCSD Medical Center, 200 West Arbor Dr, San Diego, CA 92103-8378; e-mail: t1morris{at}ucsd.edu

Abstract

Background: Low-molecular-weight heparin (LMWH) is a popular alternative to unfractionated heparin (UH) for the treatment of pulmonary embolism (PE) and deep vein thrombosis (DVT), in part based on the perception of a lower risk for heparin-induced thrombocytopenia (HIT). To investigate the evidence supporting this perception, we performed a metaanalysis to compare the incidence of thrombocytopenia between LMWH and UH during PE and/or DVT treatment.

Methods: Randomized trials comparing LMWH with UH for PE and/or DVT treatment were searched for in the MEDLINE database, bibliographies, and by correspondence with published investigators. Two reviewers independently selected high-quality studies and extracted data regarding heparin-associated thrombocytopenia (HAT), HIT confirmed by laboratory testing, and heparin-induced thrombocytopenia with thrombosis (HITT). Outcome rates between LMWH and UH were compared using a binomial, generalized linear mixed model with a logit link and Gaussian random effects for study.

Results: Thirteen studies involving 5,275 patients met inclusion criteria. There were no statistically significant differences in HAT rates between the two treatments (LMWH, 1.2%; UH, 1.5%; p = 0.246). The incidence of documented HIT and HITT was too low to make an adequate comparison between groups.

Conclusions: Our review disclosed no statistically significant difference in HAT between LMWH and UH and insufficient evidence to conclude that HIT and HITT rates were different between them. There was no evidence from randomized comparative trials to support the contention that patients receiving treatment for PE or DVT with UH are more prone to these complications than those receiving LMWH.

Key Words: deep vein thrombosis • heparin-associated thrombocytopenia • heparin-induced thrombocytopenia • heparin-induced thrombocytopenia with thrombosis • low-molecular-weight heparin • pulmonary embolism • unfractionated heparin

Related Editorial

So, Does Low-Molecular-Weight Heparin Cause Less Heparin-Induced Thrombocytopenia Than Unfractionated Heparin or Not?

Theodore E. Warkentin and Andreas Greinacher
Chest 2007 132: 1108-1110. [Full Text] [PDF]

This article has been cited by other articles:

				T. E. Warkentin and A. Greinacher So, Does Low-Molecular-Weight Heparin Cause Less Heparin-Induced Thrombocytopenia Than Unfractionated Heparin or Not? Chest, October 1, 2007; 132(4): 1108 - 1110. [Full Text] [PDF]