From the Department of Pathophysiology, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia (BAV), and Einthoven Laboratory for Experimental Vascular Medicine (NvR, SCC, FRR, and WML) and the Departments of Thrombosis and Hemostasis (NvR) and Clinical Epidemiology (SCC, FRR, and WML), Leiden University Medical Center, Leiden, The Netherlands.
Am J Clin Nutr. 2015 Mar;101(3):606-12. doi: 10.3945/ajcn.114.095398. Epub 2015 Jan 14.
Whether vitamin supplements decrease venous thrombosis risk is controversial. Previous reports did not all take confounding fully into account, either by randomization or by extensive adjustment.
The aim of our study was to determine whether vitamin supplementation decreases the risk of venous thrombosis.
A large case-control study included 2506 patients with venous thrombosis, 2506 partner controls, and 2684 random-digit dialing (RDD) controls. When patients were compared with RDD controls, unconditional logistic regression was used to calculate ORs with 95% CIs. When patients were compared with partner controls, conditional logistic regression was used, providing further adjustment for unmeasured confounding.
Vitamin use yielded a 37% lower risk of venous thrombosis than no vitamin use (OR: 0.63; 95% CI: 0.57, 0.70) when comparing patients with RDD controls. Adjustment for several putative confounders did not change the estimate (OR: 0.68; 95% CI: 0.61, 0.77). The fully adjusted ORs for vitamin A, vitamin B-6, vitamin B-12, folic acid, vitamin C, vitamin D, vitamin E, and multivitamin use were in the same range. However, when patients were compared with partner controls, ORs attenuated to unity. Results were similar for provoked and unprovoked events, as well as for deep vein thrombosis and pulmonary embolism.
After extensive adjustments, vitamin supplementation was no longer associated with a decreased risk of venous thrombosis in this study. Previous positive results may have been spurious as a result of uncontrolled confounding.
维生素补充剂是否会降低静脉血栓形成的风险存在争议。以前的报告都没有充分考虑到混杂因素，要么没有随机化，要么没有充分调整。
我们的研究旨在确定维生素补充是否会降低静脉血栓形成的风险。
一项大型病例对照研究纳入了 2506 例静脉血栓形成患者、2506 名配对对照者和 2684 名随机数字拨号（RDD）对照者。当患者与 RDD 对照者进行比较时，采用非条件逻辑回归计算 OR 值及其 95%CI。当患者与配对对照者进行比较时，采用条件逻辑回归，进一步调整未测量的混杂因素。
与 RDD 对照者相比，患者使用维生素的静脉血栓形成风险比不使用维生素低 37%（OR：0.63；95%CI：0.57，0.70）。调整几个潜在混杂因素后，该估计值并未改变（OR：0.68；95%CI：0.61，0.77）。维生素 A、维生素 B-6、维生素 B-12、叶酸、维生素 C、维生素 D、维生素 E 和多种维生素使用的完全调整 OR 范围相同。然而，当患者与配对对照者进行比较时，OR 值减弱至 1。对于诱发性和非诱发性事件，以及深静脉血栓形成和肺栓塞，结果也相似。
在进行了广泛调整后，本研究中维生素补充与静脉血栓形成风险降低无关。以前的阳性结果可能是由于未控制的混杂因素导致的虚假结果。
