A METAANALYSIS OF METHODS TO PREVENT VENOUS THROMBOEMBOLISM FOLLOWINGTOTAL HIP-REPLACEMENT

Objective.-While several methods of prophylaxis have been shown to red uce the risk of venous thromboembolism following total hip replacement , the safest and most effective agent is unclear. To clarify this issu e, we performed a meta-analysis of the randomized trials of methods us ed to prevent venous thromboembolism following total hip replacement. Data Source.-English-language human studies articles from 1966 through 1993 were obtained from a MEDLINE database search with indexing terms including thromboembolism, hip replacement or hip prosthesis, and ran domized controlled trials. Additional references were obtained from st udy bibliographies. Study Selection.-The following criteria were used to select studies for inclusion: study design-randomized clinical tria l; study population-patients undergoing elective total hip replacement ; interventions-aspirin, warfarin, dextran, heparin, low-molecular-wei ght heparin, compression stockings; and outcomes-venous thromboembolis m, major hemorrhage. Data Extraction.-Methodological and descriptive d ata from each study were abstracted by one author who was blinded to q uantitative outcomes data. Data Synthesis.-Ninety-one treatment groups and 25 control groups were identified from 56 trials. Four treatment groups were excluded because of rarely used combinations. Trial popula tions were clinically homogeneous. When compared with the control arm, all treatments except aspirin reduced the risk of all deep venous thr omboses (risk differences range, 0.18 to 0.31; all P values <.05). All treatments except aspirin reduced the risk of proximal venous thrombo sis (risk differences range, 0.09 to 0.18; all P values <.05). Only lo w-molecular-weight heparin and stockings reduced the risk of pulmonary embolism, both with risk differences equal to 0.02. The crude risks o f clinically important bleeding as defined by the individual trials we re 0% for stockings, 0.3% for controls, and 1.8% for low-molecular-wei ght heparin. Conclusions.-The results suggest that low-molecular-weigh t heparin and compression stockings have the greatest relative efficac y in preventing venous thromboembolism following total hip replacement . Low-molecular-weight heparin may be more effective, though at a smal l risk of clinically important bleeding.