The Rothman Institute of Orthopaedics, Thomas Jefferson University Hospital, 925 Chestnut Street, 5th Floor, Philadelphia, PA 19107, USA.
Clin Orthop Relat Res. 2012 Feb;470(2):547-54. doi: 10.1007/s11999-011-2007-7.
Preventing pulmonary embolism is a priority after major musculoskeletal surgery. The literature contains discrepant data regarding the influence of anticoagulation on the incidence of pulmonary embolism after joint arthroplasty. The American College of Chest Physicians guidelines recommend administration of oral anticoagulants (warfarin), aiming for an international normalized ratio (INR) level between 2 and 3. However, recent studies show aggressive anticoagulation (INR > 2) can lead to hematoma formation and increased risk of subsequent infection.
QUESTIONS/PURPOSES: We asked whether an INR greater than 2 protects against pulmonary embolism.
We identified 9112 patients with 10,122 admissions for joint arthroplasty between 2004 and 2008. All patients received warfarin for prophylaxis, aiming for an INR level of 2 or lower. We assessed 609 of 10,122 admissions (6%) for pulmonary embolism using CT, ventilation/perfusion scan, or pulmonary angiography, and 163 of 10,122 admissions (1.6%) had a proven pulmonary embolism.
Fifteen of 163 admissions (9%) had an INR greater than 2 before or on the day of workup compared to 35 of 446 admissions (8%) who were negative. We observed no difference between the INR values in patients with or without pulmonary embolism.
We found no clinically relevant difference in the INR values of patients who did or did not develop pulmonary embolism. The risk of bleeding should be weighed against the risk of pulmonary embolism when determining an appropriate target INR for each patient, as an INR less than 2 may reduce the risk of bleeding while still protecting against pulmonary embolism.
Level III, therapeutic study. See Instructions to Authors for a complete description of levels of evidence.
预防深静脉血栓栓塞症是大骨科手术后的首要任务。文献中关于关节置换术后抗凝治疗对肺栓塞发生率的影响存在不一致的数据。美国胸科医师学会指南推荐口服抗凝剂（华法林）治疗，目标国际标准化比值（INR）在 2 到 3 之间。然而，最近的研究表明，积极抗凝（INR>2）可导致血肿形成，并增加随后感染的风险。
问题/目的：我们研究 INR 大于 2 是否能预防肺栓塞。
我们在 2004 年至 2008 年间，确定了 9112 例接受关节置换术的患者和 10122 例住院患者。所有患者接受华法林预防治疗，目标 INR 水平为 2 或更低。我们通过 CT、通气/灌注扫描或肺动脉造影评估了 10122 例住院患者中的 609 例（6%）的肺栓塞情况，10122 例住院患者中有 163 例（1.6%）被证实患有肺栓塞。
在接受检查的 163 例住院患者中，有 15 例（9%）在检查前或检查当天的 INR 大于 2，而在 446 例未发生肺栓塞的住院患者中，有 35 例（8%）的 INR 大于 2。我们没有观察到肺栓塞患者与非肺栓塞患者的 INR 值之间存在差异。
我们发现发生肺栓塞与未发生肺栓塞的患者的 INR 值没有临床相关性差异。在确定每个患者的合适 INR 目标时，应权衡出血风险与肺栓塞风险，因为 INR 小于 2 可能降低出血风险，同时仍能预防肺栓塞。
III 级，治疗性研究。详见《作者须知》中对证据水平的完整描述。
