BACKGROUND Early administration of the antifibrinolytic drug tranexamic acid reduces death from bleeding in trauma and postpartum haemorrhage. We examined how the effectiveness and safety of antifibrinolytic drugs varies by the baseline risk of death as a result of bleeding. METHODS We performed an individual patient-level data meta-analysis of randomised trials including more than 1000 patients that assessed antifibrinolytics in acute severe bleeding. We identified trials performed between January 1, 1946 and July 5, 2018 (PROSPERO, number 42016052155). RESULTS Two randomised trials were selected where 28 333 patients received tranexamic acid treatment within 3 h after the onset of acute bleeding. Baseline characteristics to estimate the risk of death as a result of bleeding were divided into four categories: Low (0-5%), intermediate (6-10%), high (11-20%), and very high (>20%). Most patients had a low baseline risk of death as a result of bleeding (23 008 [81%]). Deaths as a result of bleeding occurred in all baseline risk categories with 240 (1%), 202 (8%), 232 (14%), and 357 (30%) deaths in the low-, intermediate-, high-, and very high-risk categories, respectively. The effectiveness of tranexamic acid did not vary by baseline risk when given within 3 h after bleeding onset (P=0.51 for interaction term). There was no increased risk of vascular occlusive events with tranexamic acid and it did not vary by baseline risk categories (P=0.25). CONCLUSIONS Tranexamic acid appears to be safe and effective regardless of baseline risk of death. Because many deaths are in patients at low and intermediate risk, tranexamic acid use should not be restricted to the most severely injured or bleeding patients.

中文翻译：

---

氨甲环酸对急性出血患者死亡的基线危险的影响：一项对来自28 333例患者的单个患者水平数据的荟萃分析。

背景技术抗纤维蛋白溶解药物氨甲环酸的早期给药减少了创伤和产后出血中出血的死亡。我们研究了抗纤溶药物的有效性和安全性如何因出血导致的死亡基线风险而变化。方法我们对随机试验进行了患者水平的数据荟萃分析，其中包括1000多例评估抗纤溶药物治疗急性严重出血的患者。我们确定了1946年1月1日至2018年7月5日进行的试验（PROSPERO，编号42016052155）。结果选择了两项随机试验，其中28 333例患者在急性出血发作后3小时内接受了氨甲环酸的治疗。估计因出血而死亡的基线特征分为四类：低（0-5％），中（6-10％），高（11-20％）和非常高（> 20％）。大多数患者因出血而导致的基线死亡风险较低（23 008 [81％]）。在所有基线风险类别中，均因出血而死亡，其中低，中，高和高死亡率分别为240（1％），202（8％），232（14％）和357（30％）。分别是非常高风险的类别。出血发作后3小时内给予氨甲环酸的有效性随基线风险而变化（相互作用期P = 0.51）。氨甲环酸并没有增加血管闭塞事件的风险，并且按基线风险类别也没有变化（P = 0.25）。结论无论基线死亡风险如何，氨甲环酸似乎都是安全有效的。由于中低风险患者中有许多死亡，