Eekhoff E M, Rosendaal F R, Vandenbroucke J P
Dept. of Epidemiology, Leiden University Medical Center, The Netherlands.
Thromb Haemost. 2000 Mar;83(3):408-11.
Deep venous thrombosis is a common disease, with genetic and acquired risk factors. Many patients have a history of minor events (short periods of immobilisation such as prolonged travel, short illness, minor surgery or injuries) before onset of venous thrombosis. However, the role of these minor events has received little formal study. Also, we do not know how minor events might interact with the presence of genetic prothrombotic defects (factor V Leiden mutation, factor II mutation, protein C, S and antithrombin deficiency).
On the basis of case-control data from a thrombosis service in the Netherlands, we added a follow-up period for a case-cross-over analysis of minor events as risk factors, and a case-only analysis for the interaction with factor V Leiden. A total of 187 patients with first, objectively diagnosed venous thrombosis of the legs, aged 15-70, without underlying malignancies and without major acquired risk factors entered the study. For the analysis of minor events in the case-cross-over analysis, we used a matched odds ratio; in the case-only analysis, we used the multiplicative synergy index.
In 32.6% of the 187 patients with deep venous thrombosis who did not have major acquired risk factors, minor events were the only external risk factors. Minor events increased the risk of thrombosis about 3-fold, as estimated in the case-cross-over analysis (odds ratio 2.9, 95% confidence interval 1.5-5.4). The synergy index between minor events and factor V Leiden mutation in the case-only analysis was 0.7 (95% confidence interval 0.3-1.5). Therefore, persons with factor V Leiden mutation who experience a minor event will have an estimated risk increase of about 17-fold, which exceeds the sum of the individual risk factors.
Minor events are likely to play an important role in the development of deep venous thrombosis, especially in the presence of genetic prothrombotic conditions.
深静脉血栓形成是一种常见疾病，存在遗传和后天危险因素。许多患者在静脉血栓形成发作前有轻微事件史（如长时间旅行、短期患病、小手术或受伤等短期制动）。然而，这些轻微事件的作用很少得到正式研究。此外，我们不知道轻微事件如何与遗传性血栓前缺陷（因子V莱顿突变、因子II突变、蛋白C、S缺乏和抗凝血酶缺乏）相互作用。
基于荷兰一家血栓形成服务机构的病例对照数据，我们增加了一个随访期，用于对轻微事件作为危险因素进行病例交叉分析，以及对与因子V莱顿的相互作用进行病例对照分析。共有187例年龄在15 - 70岁、首次客观诊断为下肢静脉血栓形成、无潜在恶性肿瘤且无主要后天危险因素的患者进入研究。在病例交叉分析中分析轻微事件时，我们使用匹配比值比；在病例对照分析中，我们使用乘法协同指数。
在187例无主要后天危险因素的深静脉血栓形成患者中，32.6%的患者轻微事件是唯一的外部危险因素。如病例交叉分析所估计，轻微事件使血栓形成风险增加约3倍（比值比2.9，95%置信区间1.5 - 5.4）。病例对照分析中轻微事件与因子V莱顿突变之间的协同指数为0.7（95%置信区间0.3 - 1.5）。因此，发生轻微事件的因子V莱顿突变患者估计风险增加约17倍，超过了个体危险因素之和。
轻微事件可能在深静脉血栓形成的发展中起重要作用，尤其是在存在遗传性血栓前状况时。
