Hull R D, Pineo G F, Stein P D, Mah A F, MacIsaac S M, Dahl O E, Ghali W A, Butcher M S, Brant R F, Bergqvist D, Hamulyák K, Francis C W, Marder V J, Raskob G E
Thrombosis Research Unit, University of Calgary, Alberta, Canada.
Arch Intern Med. 2001 Sep 10;161(16):1952-60. doi: 10.1001/archinte.161.16.1952.
Perioperative and postoperative venous thrombosis are common in patients undergoing elective hip surgery. Prophylactic regimens include subcutaneous low-molecular-weight heparin 12 hours or more before or after surgery and oral anticoagulants. Recent clinical trials suggest that low-molecular-weight heparin initiated in closer proximity to surgery is more effective than the present clinical practice. We performed a systematic review of the literature to assess the efficacy and safety of low-molecular-weight heparin administered at different times in relation to surgery vs oral anticoagulant prophylaxis.
Reviewers (A.F.M. and S.M.M.) identified studies by searching MEDLINE, reviewing references from retrieved articles, scanning abstracts from conference proceedings, and contacting investigators and pharmaceutical companies. Randomized trials comparing low-molecular-weight heparin administered at different times relative to surgery with oral anticoagulants in patients undergoing elective hip arthroplasty, evaluated using contrast phlebography, were selected. Two reviewers (A.F.M. and S.M.M.) extracted data independently.
The literature review identified 4 randomized trials meeting predefined inclusion criteria. The results indicate that low-molecular-weight heparin initiated in close proximity to surgery resulted in absolute risk reductions of 11% to 13% for deep vein thrombosis, corresponding to relative risk reductions of 43% to 55% compared with oral anticoagulants. Low-molecular-weight heparin initiated 12 hours before surgery or 12 to 24 hours postoperatively was not more effective than oral anticoagulants. Low-molecular-weight heparin initiated postoperatively in close proximity to surgery at half the usual dose was not associated with a clinically or statistically significant increase in major bleeding rates (P =.16).
The timing of initiating low-molecular-weight heparin significantly influences antithrombotic effectiveness. The practice of delayed initiation of low-molecular-weight heparin prophylaxis results in suboptimal antithrombotic effectiveness without a substantive safety advantage.
择期髋关节手术患者围手术期和术后静脉血栓形成很常见。预防方案包括术前或术后12小时及更长时间皮下注射低分子量肝素和口服抗凝剂。近期临床试验表明，更接近手术时开始使用低分子量肝素比目前的临床实践更有效。我们对文献进行了系统评价，以评估与手术相关的不同时间给予低分子量肝素与口服抗凝剂预防的疗效和安全性。
评审人员（A.F.M.和S.M.M.）通过检索MEDLINE、查阅检索文章的参考文献、浏览会议论文摘要以及联系研究者和制药公司来识别研究。选择在接受择期髋关节置换术的患者中，将与手术相关的不同时间给予低分子量肝素与口服抗凝剂进行比较的随机试验，采用静脉造影评估。两名评审人员（A.F.M.和S.M.M.）独立提取数据。
文献综述确定了4项符合预定义纳入标准的随机试验。结果表明，更接近手术时开始使用低分子量肝素可使深静脉血栓形成的绝对风险降低11%至13%，与口服抗凝剂相比，相对风险降低43%至55%。术前12小时或术后12至24小时开始使用低分子量肝素并不比口服抗凝剂更有效。术后更接近手术时以通常剂量的一半开始使用低分子量肝素与主要出血率在临床或统计学上无显著增加相关（P = 0.16）。
开始使用低分子量肝素的时间显著影响抗血栓效果。延迟开始低分子量肝素预防的做法导致抗血栓效果欠佳，且无实质性的安全优势。
