Treatment of venous thromboembolism with low-molecular-weight heparin: a synthesis of the evidence published in systematic literature reviews.
OBJECTIVE
To evaluate the methodology and cumulative evidence presented in systematic reviews of clinical trials comparing low-molecular-weight heparin (LMWH) with unfractionated heparin (UFH) for the treatment of venous thromboembolism.


METHODS
We reviewed all systematic reviews of clinical trials published until March 2002. Fourteen systematic literature reviews were published between 1994 and 2000. Deficiencies in methodological quality were common, particularly in the description of search strategies, assessment of clinical trial quality, and methods used to combine results.


RESULTS
Results of reviews indicate that LMWH is superior to UFH for the treatment of venous thromboembolism, particularly in reducing mortality. Patients with isolated deep venous thrombosis or deep venous thrombosis with concomitant pulmonary embolism seemed to have similar benefit. However, the benefits of LMWH over UFH were smaller in magnitude in reviews that included more recent clinical trials.
Krishnan
J A
JA
Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, USA. jkrishn2@jhmi.edu
Segal
J B
JB
Streiff
M B
MB
Bolger
D T
DT
Eng
J
J
Jenckes
M W
MW
Tamariz
L J
LJ
Bass
E B
EB
D000925:Anticoagulants / Q000627:therapeutic use*; D002986:Clinical Trials as Topic; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use*; D006801:Humans; D011655:Pulmonary Embolism / Q000188:drug therapy*; D012008:Recurrence; D013923:Thromboembolism / Q000188:drug therapy*; D016896:Treatment Outcome; D020246:Venous Thrombosis / Q000188:drug therapy*
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight