title: Low-molecular-weight heparin prophylaxis: preoperative versus postoperative initiation in patients undergoing elective hip surgery.
abstract: Administration of low-molecular-weight heparin prophylaxis in elective hip implant patients commonly begins 12 h preoperatively in European practices to optimize effectiveness, and 12 to 24 h postoperatively in North American practices to optimize safety. A meta-analysis comparing these two treatment regimes revealed that preoperative initiation demonstrated greater efficacy and superior safety for patients (10.0% rate of total deep-vein thrombosis vs. 15.3%, P = .023). In addition to the pre/postsurgical debate, proximity of initiation of low-molecular-weight heparin in relation to surgery is an issue of critical importance. Recent studies revealed that beginning therapy immediately within 2 h preoperatively or 6 h postoperatively dramatically decreased the risk of venous thrombosis. An investigation of low-molecular-weight heparin prophylaxis initiated 2 h before elective hip surgery or approximately 6 h after surgery compared with warfarin sodium revealed that total and proximal deep-vein thrombosis rates were reduced in patients receiving low-molecular-weight heparin compared with warfarin. The frequencies of deep-vein thrombosis for patients receiving preoperative and postoperative dalteparin vs. warfarin for all deep-vein thrombosis were 36 of 337 (10.7%, P < .001) and 44 of 336 (13.1%, P < .001) vs. 81 of 338 (24.0%); and for proximal deep-vein thrombosis were 3 of 354 (0.8%, P = .035) and 3 of 358 (0.8%, P = .033) vs. 11 of 363 (3.0%). Relative risk reductions for the dalteparin groups vs. warfarin ranged from 45% to 72%. In this case, low-molecular-weight heparin administered in close proximity to surgery provided superior efficacy over warfarin. Major bleeding was significantly increased with the preoperative regimen but not the postoperative regimen.
authors.affiliation: University of Calgary, Calgary, Alberta, Canada. jeanne.sheldon@crha-health.ab.ca
authors.forename: R D
authors.initials: RD
authors.lastname: Hull
authors.forename: G F
authors.initials: GF
authors.lastname: Pineo
authors.forename: S
authors.initials: S
authors.lastname: MacIsaac
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000592:standards; D017558:Elective Surgical Procedures / Q000592:standards; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage*; D006801:Humans; D011182:Postoperative Care; D011300:Preoperative Care; D020246:Venous Thrombosis / Q000188:drug therapy / Q000453:epidemiology / Q000517:prevention & control*
chemical_list: D006495:Heparin, Low-Molecular-Weight