目的：华法林治疗的困难导致人们推测每日补充低剂量维生素K可能改善抗凝控制和临床结局。因此，我们试图回顾现有的医学文献，系统地检查低剂量维生素K补充剂在减少因使用维生素K拮抗剂（VKA）引起的临床相关不良事件和稳定国际标准化比率（INR）方面的有效性。
方法：我们搜索了Medline和Embase数据库，Cochrane图书馆,国际医药文摘,以及美国国立卫生研究院临床试验注册中心对接受VKA的患者补充维生素K与安慰剂的随机对照试验。我们评估了出血的结果，血栓栓塞事件,和INR治疗范围内的时间百分比（TTR），通过使用建议分级评估，摘要研究中证据质量评级的开发和评估系统。
方法：1970年至2012年8月发表的所有符合我们搜索策略的随机对照试验研究。
方法：接受VKA治疗的18岁以上患者。
结果：在我们确定和筛选的624项研究中，三项研究(626例患者)纳入荟萃分析.大多数患者在基线时具有令人满意的TTR。我们发现了低质量的证据-由于不精确和偏差风险而降级(即，研究设计和/或执行方面的限制）-使用维生素K（100至200μg）对出血事件（相对风险[RR]3.2，95％置信区间[CI]0.2-64.2）和血栓栓塞事件（RR2.2，95％CI0.1-47.5）没有影响，对TTR有显着但临床上不重要的影响，绝对增加3.5％（95％CI1.1-6.0）。
结论：本荟萃分析，尽管研究很少，总体质量低，提示低剂量（100至200μg）维生素K补充剂对减少服用VKAs的患者的临床相关不良事件没有有益作用，尽管TTR略有改善。数据不足,然而,来自不稳定INR患者。
OBJECTIVE: Difficulties managing warfarin therapy have led to speculation that daily supplementation with a low dose of vitamin K might improve anticoagulation control and clinical outcomes. Thus we sought to
review the available medical literature systematically examining the effectiveness of low-dose vitamin K supplementation for the reduction of clinically relevant adverse events due to vitamin K antagonist (VKA) use and for stabilization of the international normalized ratio (INR).
METHODS: We searched the Medline and Embase databases, the Cochrane Library, International Pharmaceutical Abstracts, and the U.S. National Institutes of Health clinical trials registry for randomized controlled trials of vitamin K supplementation versus placebo in patients receiving a VKA. We evaluated the outcomes of hemorrhage, thromboembolic events, and percentage of time in therapeutic range (TTR) of INRs by using the Grading of Recommendations Assessment, Development and Evaluation system for rating quality of evidence in the abstracted studies.
METHODS: All randomized controlled trials studies published between 1970 and August 2012 which fitted our search strategy.
METHODS: Patients over the age of 18 years on VKA therapy.
RESULTS: Of the 624 studies we identified and screened, three studies (626 patients) were included in the meta-analysis. Most of the patients had a satisfactory TTR at baseline. We found low-quality evidence--downgraded for imprecision and risk of bias (i.e., limitation in study design and/or execution)--of no effect of vitamin K use (100 to 200 μg) on hemorrhagic events (relative risk [RR] 3.2, 95% confidence interval [CI] 0.2-64.2) and thromboembolic events (RR 2.2, 95% CI 0.1-47.5) and a significant but clinically unimportant effect on TTR with an absolute increase of 3.5% (95% CI 1.1-6.0).
CONCLUSIONS: This meta-analysis, despite the few studies and overall low quality, suggests no beneficial role of low-dose (100 to 200 μg) vitamin K supplementation on the reduction of clinically relevant adverse events in patients taking VKAs, despite a small improvement of the TTR. Data were insufficient, however, from patients with unstable INRs.
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