Spinal Cord (2007) 45, 627–631 & 2007 International Spinal Cord Society All rights reserved 1362-4393/07 $30.00 www.nature.com/sc Original Article Endogenous risk factors for deep-vein thrombosis in patients with acute spinal cord injuries S Aito*,1, R Abbate2, R Marcucci2 and E Cominelli1 1Spinal Unit, Careggi University Hospital, Florence, Italy; 2Medical division, coagulation disease, Careggi University Hospital, Florence, Italy Study design: Case–control study. Aim of the study: Investigate the presence of additional endogenous risk factors of deep-vein thrombosis (DVT). Setting: Regional Spinal Unit of Florence, Italy. Methods: A total of 43 patients with spinal lesion and a history of DVT during the acute stage of their neurological impairment (Group A) were comprehensively evaluated and the blood concentrations of the following risk factors, that are presumably associated with DVT, were determined: antithrombin III (ATIII), protein C (PC), protein S (PS), factor V Leiden, gene 200210A polymorphism, homocysteine (Hcy), inhibitor of plasminogen activator-1 (PAI-1) and lipoprotein A (LpA). The control group (Group B) consisted of 46 patients matched to Group A for sex, age, neurological status and prophylactic treatment during the acute stage, with no history of DVT. Statistical analysis was performed using the Mann–Whitney and Fisher’s exact tests. Results: Of the individuals in GroupA, 14% had no risk factor and 86% had at least one; however, in GroupB 54% had no endogenous risk factors and 46% had at least one. None of the individuals in either grouphad a deficit in their coagulation inhibitors (ATIII, PC and PS), and the LpA level was equivalent in the two groups. The levels of Hcy and PAI-1 were significantly higher in GroupA. Conclusions: Increases in the levels of plasma Hcy and PAI-1 are demonstrated to be independent risk factors for developing a DVT. Spinal Cord (2007) 45, 627–631; doi:10.1038/sj.sc.3102018; published online 16 January 2007 Keywords: deep vein thrombosis; acute spinal cord lesion; risk factor for DVT; hyperhomo- cisteinemia; PAI-1; thrombosis prophylaxis Introduction Deep-vein thrombosis (DVT) is one of the most lower limbs. The second risk factor for DVT is common and highly feared events that occurs as a hypercoagulability: some changes in hemostasis have complication of acute spinal cord lesion (SCL), as well been observed in SCI patients before the thrombotic documented in the literature.1–4,7 The reported inci- event, including increases in Factor VIII, and increased dence ranges from 9 to 90%, depending on the levels and aggregation of platelets.8 The third risk factor research methods used, the nature of the study popula- that has been identified is damage to venous endothelial tion under investigation, and the prophylactic strategy cells. that was adopted. Nevertheless, in more recent Furthermore, several clinical conditions and diseases and widespread studies, it is reported to vary between are considered to be acquired risk factors, including 10 and 30%.1–3,5,6 It is well-known that in acute SCI, all immobilization, pregnancy, chronic hearth failure, the factors that characterize the Virchow triad occur: the varicose veins, age, and obesity, all of which can first risk factor in SCI is stasis of circulating blood: increase venous stasis. On the other hand, clinical acute palsy leads to loss of the muscle pump, dilatation conditions such as trauma, surgery (eg, orthopedics, of the blood vessels, and decreased blood flow from the neurosurgery), use of central vein catheters, tumors, myocardial infarction, hematological diseases (leuke- *Correspondence: S Aito, Spinal Unit, Careggi University Hospital, mia, thrombocytosis, etc), and use of estrogens, are all 9,10 largo Palagi 1, 50139 Firenze, Italy risk factors for hypercoagulation. Risk factors for deep vein thrombosis S Aito et al 628 There are many congenital risk factors that may also large hepatically derived glycoprotein, apolipoprotein play an important role in the development of a DVT, (a), which is structurally similar to plasminogen. each one associated with an increased thrombophylic Although the mechanism through which Lp(a) promotes risk. The following have been identified as possible cardiovascular disease is yet to be elucidated, there are candidates: hereditary antithrombin III (ATIII) defi- two possible hypotheses for this activity: ciency, hereditary protein C (PC) deficiency, hereditary protein S (PS) deficiency, activated PC resistance (factor V Leiden), plasminogen activator disorders, gene 1. the apolipoprotein (a) moiety could promote throm- 20210A polymorphism (the codifying gene for pro- bogenesis and/or thrombin), inhibitor of plasminogen activator I (PAI-1) 2. its LDL-C moiety could promote atherogenesis. disorders, increased levels of lipoprotein A (LpA), the The apolipoprotein portion of Lp(a) competitively presence of antiphospholipid antibodies, and hyper- displaces plasminogen from binding sites on both fibrin homocysteinemia (congenital and acquired).9 and endothelial cells.14 Lp(a) is also associated with ATIII is the most potent inhibitor of the coagulation increased levels of PAI-1 and decreased activity of cascade, exerting some level of inhibitory activity on t-PA.15 These effects all combine to promote thrombosis virtually all of the coagulation enzymes. However, the and inhibit fibrinolysis. The physiological role of Lp(a) primary targets that ATIII inhibits are factor Xa, factor is unknown: levels are largely genetically determined, IXa, and thrombin (factor IIa). Nonetheless, it also has increase slightly with age, and vary by race. Elevated some ability to inhibit factor XIIa, factor XIa, and the levels of Lp(a) are found in patients with chronic renal complex of factor VIIa and tissue factor. The ability of failure, nephrotic syndrome, and diabetic nephro- ATIII to limit coagulation through multiple interactions pathy.16,17 makes it one of the primary natural anticoagulant Homocysteine (Hcy) is derived from the essential proteins.9,10 amino acid methionine. The levels of Hcy in the blood PC inactivates factor Va and factor VIIIa by depend on the rate of its synthesis by an extensive converting them to their inactive forms (factor V and enzymatic pathway, as well as the levels of vitamin B12, factor VIII, respectively). There are several congenital folate, and 5-methyltetrahydrofolate (produced by risk factors that are associated with loss of the activity methylenetetrahydrofolate reductase).18 Mild elevations of PC. Deficiency of PC itself is a genetic trait that in the plasma levels of Hcy result from folate and predisposes one to the formation of venous clots. In vitamin B12 deficiency and renal diseases. These eleva- addition, PS serves as a cofactor with PC in the tions in Hcy are associated with several common inactivation of factor Va and factor VIIIa. Deficiency diseases, including cardiovascular diseases. The accu- of PS therefore prevents the activity of PC.9,10 mulation of Hcy leads to increased cellular oxidative PAI-1 is a member of a family of proteins that inhibits stress, and chronic exposure to Hcy causes endothelial plasminogen activators.11 PAI-1 is a single-chain glyco- and vascular dysfunction.9,10 protein. During fibrinolysis, tissue plasminogen activa- Aim of our study was to better determine the tor (tPA) converts the inactive protein plasminogen into thrombophylic risk profile of patients during the early plasmin. Plasmin, in turn, plays a critical role in phase of spinal lesion. In order to achieve this, we fibrinolysis by degrading fibrin. PAI-1 limits the evaluated the levels of the above-mentioned endogenous production of plasmin and serves to keep fibrinolysis factors that have previously been associated with in check. PAI-1 levels are, in part, controlled on a congenital disorders. By comparing the levels of these genetic basis. Certain polymorphisms in the PAI-1 gene endogenous factors in the blood of patients, with or are associated with increased blood concentrations.11 without a DVT, we will be able to determine whether Prothrombin polymorphism G20210A and factor V they are risk factors. Leiden: these two polymorphisms were found to be associated with an increased risk for venous throm- Patients and methods boembolism. Factor V Leiden confers a hypercoagul- able state as it determines the synthesis of a modified We assessed the blood levels of the following endogen- factor V which shows an ‘in vitro’ resistance to the ous risk factors of 43 patients (Group A) with a SCL, inhibitory action of PC. Its prevalence ranges from 3 to previously admitted to the Spinal Unit of Florence 5% in the Western population. Moreover, the G20210A (from July 1999 till February 2004), and with a history polymorphism in the gene coding for prothrombin, of DVT during the acute stage (the first 30 days) after whose prevalence ranges from 2 to 3% in the Western the lesion: ATIII, PC, PS, factor V Leiden, gene 20210A population, is associated with a significantly higher risk polymorphism (the codifying gene for prothrombin), of venous thromboembolism, but the mechanism under- homocysteine, inhibitor of PAI-1, and LpA. DVT had lying this hypercoagulable effect is not well defined. An occurred in all patients during the first month following hypothesis is based on studies which have documented the lesion and they were detected using an Ultrasound that the subjects carrying such polymorphism have echo–color–doppler. The blood examinations, aimed to higher circulating levels of prothrombin.9,12,13 measure the concentration of the above-mentioned Lp(a) consists of a particle of low-density lipoprotein factors, were assessed at least 12 months after the cholesterol (LDL-C) linked by a disulfide bond to a lesion. None of them was under pharmacological Spinal Cord Risk factors for deep vein thrombosis S Aito et al 629 antithrombotic treatment during the performance of the blood leukocytes using a MagNA Pure (Roche) and blood tests. QUIAmpBlood Kit (QUIAGEN, Hilden, Germany), Group A patients were compared to 46 patients respectively.