OBJECTIVETo pool the data of studies about anticoagulation in non-massive pulmonary thromboembolism (PTE) and evaluate the efficacy and safety of low molecular weight heparin (LMWH) and unfractionated heparin (UFH) as the initial treatment.

METHODSMEDLINE CD-ROM from January 1966 to August 2003 and CBM CD-ROM from January 1978 to August 2003 were chosen for searching the randomized clinical trials (RCTs) that compared the efficacy or safety of LMWH and UFH in non-massive PTE. A meta-analysis was employed to evaluate the results of these two therapies.

RESULTSFive RCTs including 999 cases were analyzed. Compared with UFH, the combined odds ratio (OR) of LMWH in treating PTE was as follows: (1) The total OR of mortality of PTE patients treated with LMWH was 0.81 (95%CI 0.36-1.81, P > 0.05); (2) The total OR of recurrence of venous thromboembolism (VTE) in PTE patients treated with LMWH was 0.37 (95%CI 0.14-1.00, P=0.05); (3) The total OR of bleeding in LMWH was 0.47 (95%CI 0.16-1.39, P > 0.05);(4) The total OR of heparin-induced thrombocytopenia (HIT) in LMWH was 0.66 (95%CI 0.06-6.92, P > 0.05).

CONCLUSIONSLMWH and UFH can reduce the mortality and recurrence of VTE in patients with PTE in the same degree. The risk of major bleeding was similar in the two treatment groups. Initial subcutaneous therapy with the LMWH appeared to be as effective and safe as intravenous UFH in the initial treatment of PTE.