Risk Factor For Vascular Thrombosis Research Articles

Can Rosuvastatin Reduce the Risk of Thrombosis in Patients with Hypercholesterolemia with its Effect on Coagulation Factors and Homocysteine Levels?

Hypercholesterolemia is one of the main risk factors for vascular thrombosis in individuals. Therefore, the use of statins is very effective in reducing cholesterol and can reduce the risk of thrombosis in these patients. Rosuvastatin, a member of the statin family which, inhibits cholesterol synthesis. Very few studies have been done in relation to how rosuvastatin can affect thrombosis. So, this research has been tried whether rosuvastatin can have an effect on coagulation factors and homocysteine as risk factors for thrombosis in hypercholesterolemia? In this experimental study, 60 patients (30 men and 30 women with a mean age of 40- 70 years) diagnosed with hypercholesterolemia (cholesterol >250 mg/dl) participated in this research. 30 patients were prescribed rosuvastatin (20 mg/day), and 30 patients were simultaneously taken placebo for three months. All parameters, including FVIII, FV, Fibrinogen, D-Dimer, plasma homocysteine level and lipid profile, were measured before and after treatment. All the results were statistically compared between the two groups. In patients who took rosuvastatin, the drug was able to significantly reduce the concentrations of total cholesterol, triglycerides, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) (P <0.001). Also, rosuvastatin was able to reduce the concentrations of homocysteine significantly, D-Dimer (P <0.001), coagulation factor VIII and factor V (P <0.05). In patients with hypercholesterolemia who took the placebo, did not affect the mentioned variables (P >0.05). According to the results, it seems that rosuvastatin may be able to reduce the risk of thrombosis in patients by affecting coagulation factors and homocysteine levels.

Beyond the classics: The emerging value of anti-phosphatidylserine/prothrombin antibodies in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by the presence of antiphospholipid antibodies (aPLs), which can lead to thrombosis and pregnancy complications. Within the diverse range of aPLs, anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have gained significance in clinical practice. The detection of aPS/PT has proven valuable in identifying APS patients and stratifying their risk, especially when combined with other aPL tests like lupus anticoagulant (LA) and anti-β2-glycoprotein I (aβ2GPI). Multivariate analyses have confirmed aPS/PT as an independent risk factor for vascular thrombosis and obstetric complications, with its inclusion in the aPL score and the Global Anti-Phospholipid Syndrome Score (GAPSS) aiding in risk evaluation. However, challenges remain in the laboratory testing of aPS/PT, including the need for assay standardization and its lower sensitivity in certain patient populations. Further research is necessary to validate the clinical utility of aPS/PT antibodies in APS diagnosis, risk stratification, and management.

MO968: Vascular Complications of Renal Transplantation: Risk Factors and Impact on Graft Survival

Abstract BACKGROUND AND AIMS Despite the progress made in renal transplantation, vascular complications can occur, jeopardizing the prognosis of the transplant. This study aims to investigate the risk factors of vascular complications and their impact on transplant survival. METHOD We performed a retrospective longitudinal descriptive study including all patients who had a kidney transplant in a Urology department from 1986 to 2017. Transplant Vascular complications included: Arterial thrombosis (AT), Venous thrombosis (VT), hemorrhagic complications (hemorrhage and hematoma) and arterial stenosis (AS). The potential risk factors for vascular complications that were investigated included characteristics related to the recipient, the donor, the transplant and the procedure. The impact of vascular complications on transplant survival was then studied. RESULTS A total of 720 patients were included with a mean age of 32.7 years. The transplant was from a living donor in 79% and a brain-dead donor in 21%. AT occurred in 15 patients (2.1%) and VT occurred in 10 patients (1.4%). Risk factors for vascular thrombosis were recipient age &amp;gt;35 years (P = 0.001; OR = 10.78), recipient smoking (P = 0.005; OR = 1.8), multiple arteries (P &amp;lt; 0.001; OR = 1.45) and prolonged warm ischemia (P = 0.02). Perirenal hematoma occurred in 11 patients (1.5%) and hemorrhage occurred in six patients (0.8%). The risk factors for bleeding complications were a prolonged pre-transplantation dialysis time (P = 0.03; OR = 1.35), and prolonged warm ischemia (P = 0.02; OR = 1.26). AS was the most frequent vascular complication, occurring in 20 cases (2.8%) and no risk factors were identified. Transplant survival was 77.9% at 5 years, with a median survival of 15.9 years. Vascular thrombosis led to the loss of the transplant in all cases, and externalized hemorrhage significantly reduced transplant survival (P &amp;lt; 0.001). Perirenal hematoma (P = 0.42) and transplant artery stenosis (P = 0.25) had no impact on transplant survival (Figure 1). CONCLUSION Our study showed that the vascular complications impacted the survival of the transplant and that they were related to factors related to the recipient, the transplant and the procedure insisting on a multidisciplinary and personalized management for each case.

Anti-prothrombin autoantibodies enriched after infection with SARS-CoV-2 and influenced by strength of antibody response against SARS-CoV-2 proteins.

Antiphospholipid antibodies (aPL), assumed to cause antiphospholipid syndrome (APS), are notorious for their heterogeneity in targeting phospholipids and phospholipid-binding proteins. The persistent presence of Lupus anticoagulant and/or aPL against cardiolipin and/or β2-glycoprotein I have been shown to be independent risk factors for vascular thrombosis and pregnancy morbidity in APS. aPL production is thought to be triggered by-among other factors-viral infections, though infection-associated aPL have mostly been considered non-pathogenic. Recently, the potential pathogenicity of infection-associated aPL has gained momentum since an increasing number of patients infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been described with coagulation abnormalities and hyperinflammation, together with the presence of aPL. Here, we present data from a multicentric, mixed-severity study including three cohorts of individuals who contracted SARS-CoV-2 as well as non-infected blood donors. We simultaneously measured 10 different criteria and non-criteria aPL (IgM and IgG) by using a line immunoassay. Further, IgG antibody response against three SARS-CoV-2 proteins was investigated using tripartite automated blood immunoassay technology. Our analyses revealed that selected non-criteria aPL were enriched concomitant to or after an infection with SARS-CoV-2. Linear mixed-effects models suggest an association of aPL with prothrombin (PT). The strength of the antibody response against SARS-CoV-2 was further influenced by SARS-CoV-2 disease severity and sex of the individuals. In conclusion, our study is the first to report an association between disease severity, anti-SARS-CoV-2 immunoreactivity, and aPL against PT in patients with SARS-CoV-2.

Vascular Thrombosis Leading to Graft Failure Following Pediatric Liver Transplantation

Background: Vascular thrombosis is an uncommon but devastating complication following pediatric liver transplantation and is a major cause of graft failure, re-transplantation, and death. Hematologic complications of transplant occur more frequently in children compared to adults; however, existing data regarding risk factors and outcomes are limited and rely on single center series. The purpose of this study is to investigate the risk factors for vascular thrombosis leading to graft failure after pediatric liver transplant using a population-based sample.Methods: We queried the United Network of Organ Sharing (UNOS) database from 2003-2014 for pediatric liver transplant recipients (age 0-18 years). Recipients were stratified by post-transplant vascular thrombosis causing graft failure, including hepatic artery thrombosis, portal venous thrombosis, and other or unknown vascular thrombosis. Thrombosis and non-thrombosis groups were compared by univariate analysis of demographic characteristics, pre-transplant characteristics, and transplant characteristics. P-values <0.05 were considered statistically significant. Backwards-stepwise logistic regression was used to identify factors associated with hepatic artery thrombosis leading to graft failure.Results: Of 11,656 children undergoing liver transplantation, 581 (4.9%) were identified with postoperative arterial or venous thrombosis leading to graft failure (Table 1). Children that developed vascular thromboses were younger (3 [IQR 1-9] vs. 6 [IQR 2-13], p<0.001), weighed less at time of transplant (15.0 [IQR 10.2-27.9] vs. 19.6 [IQR 11.3-41.3], p<0.001), and were more likely to have received a partial liver transplant (30.8% vs. 24.4%, p<0.008). Patients with thromboses were more likely to have received a previous transplant (29.6% vs. 16.0%, p<0.001), and the rate of thrombosis was notably elevated in patients who received a transplant for a prior transplant complication (10.6%). Vascular thrombosis was associated with lower MELD/PELD scores (14 [IQR 17-23] vs. 17 [9-26], p=0.047); however, individual recipient lab values at the time of transplant did not distinguish between the two groups. Multivariate analysis demonstrated that younger age, transplant for prior transplant complication or non-metabolic indication, and lower MELD/PELD scores were independent risk factors specifically for hepatic artery thrombosis (Table 2). Children who developed thromboses were significantly more likely to undergo re-transplantation, and had increased mortality due to graft failure but did not have an increased overall mortality (Table 1).Conclusion: This study, the largest national study to date, confirms that pediatric liver transplant recipients are at significant risk for vascular thrombosis, which greatly increases the rate of re-transplantation. Factors associated with increased risk of thrombosis include age, indication for transplant, and MELD/PELD score, suggesting interplay between mechanical factors, underlying disease process, and the complex and overlapping interactions that make up the pediatric coagulome, inadequately assessed by standard lab tests. Further study is needed to characterize these interactions in order to better identify patients at risk and direct anti-thrombotic therapy. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Association between serum homocysteine levels and methylene-tetrahydrofolate-reductase gene polymorphism in patients with stroke: A study from a tertiary care teaching hospital from Central India

Background: Hyperhomocysteinemia (HHcy) is a well-established risk factor for vascular thrombosis leading to stroke. Homocysteine (Hcy) is mainly synthesized in the methionine cycle, and it is an intermediate during the conversion of methionine to cysteine. HHcy can develop by polymorphism of several enzymes like methylene-tetrahydrofolate-reductase (MTHFR) mutation and due to deficiency of co-factor Vitamins such as B12, B6, and folic acid. This study was planned to see the association between HHcy and MTHFR gene polymorphism in patients with stroke in populations from central India. Methods: Seventy-two patients diagnosed with stroke aged 18 years and above who met the inclusion criteria were selected. Hcy level and MTHFR mutation were identified among patients of stroke. Results: Forty-two patients (58.33%) were diagnosed with acute ischemic stroke as compared to cerebral venous thrombosis (30, 41.66%) from a total of 72 patients. The statistical analysis projected that the HHcy diagnosed among more (45, 62.5.0%) cases with stroke who had aged ≤45 years as compared to cases who had aged >45 years (17, 23.6%). None of our patients tested positive for either CT (Heterozygous) or TT(Homozygous) genotypes. Conclusions: HHcy is not associated with MTHFR gene mutation in our study group, and this possibly is related to the deficiency of co-factors in Hcy metabolism. Young age group stroke patients have higher Hcy levels.

Early Vascular Thrombosis After Kidney Transplantation: Can We Predict Patients at Risk?

BackgroundRenal transplant is the therapy of choice for patients with chronic renal disease. In recent years, improvement in immunosuppressive drugs reduced early graft loss associated with acute rejection. However, vascular thrombosis, accounting for 5% of early graft loss, can sensitize the recipient for human leukocyte antibodies, reducing the chance for a second transplant. The aim of this study was to identify risk factors for vascular thrombosis in a single transplant center, to design specific prevention protocol. MethodsThis was a retrospective, case-control study. From the Renal Transplant Unit database, we identified 21 cases of vascular thrombosis in recipients of kidneys from deceased donors. Recipients from the contralateral kidney from the same donor, without vascular complications, were assigned to the control group. Data analyzed included donor, recipient, transplant surgery, and post-operative follow-up. The local ethics committee approved the protocol. ResultsThrombosis and control groups were comparable for recipient characteristics, cold ischemia time, organ side (right or left), and site of arterial anastomosis. We observed an increased risk for vascular thrombosis in kidneys with multiple veins (odds ratio, 11.32; P = .03). Organ retrieval surgery complications, such as vascular lesions or heterogeneous perfusion, despite normal pre-implantation biopsy, were considered risk factors for vascular thrombosis within the first post-operative day (odds ratio, 7.1; P = .03). ConclusionsIn this series, multiple renal vein and organ retrieval surgery complications were risk factors for early vascular thrombosis.

THU0303 Hypovitaminosis D and the Metabolic Syndrome in Patients with Systemic Lupus Erythematosus (SLE)

BackgroundLow vitamin D level has been linked to cardiovascular diseases and mortality in the general population. Hypovitaminosis D is associated with certain traditional vascular risk factors in patients with SLE.ObjectivesTo...

Platelet aggregation in children with end-stage kidney disease in relation to level of L-arginine as a risk factor for vascular thrombosis

objectives: The aim of the study is to evaluate the level of L‑arginine in patients of end‑stage kidney disease (ESKD) under regular hemodialysis and to determine its relation to platelet aggregation as a risk factor for vascular thrombosis which is a very important complication that affects the life span of those patients. In addition, we also tried to establish the relationship between L‑arginine, platelet aggregation, and nutritional state of patients with ESKD. s ubjects and Methods: Our study was “a case‑control study”, comparing data between 30 patients with ESKD under treatment with regular hemodialysis‑group (A); group A1 (16)‑patients with ESKD on regular hemodialysis with malnutrition, group A2 (14)‑patients with ESKD on regular hemodialysis with normal nutrition state, and group B 10 subjects as healthy control group, each patient was evaluated for serum arginine level by high‑performance liquid chromatography, and platelet aggregation, as well as other routine investigations. A thorough clinical history and examination were performed for all the patients. results: Our study shows significant higher level of platelet aggregation to ADP in group A than group B (119±11.9% and 81.1±6.5% respectively, P<0.05), a lower level of serum arginine in group A (71±45.3 μg/L) than in group B (120.5±14.6 μg/L) with P<0.05. Also our study shows a lower level of serum arginine in group A1 (60.5±12.3 μg/L) than group A2 (83±27 μg/L) and a lower level in group A2 than group B (120.5±14.6 μg//l), and we found a negative correlation between serum arginine level and platelet aggregation expressing a more risk for thrombosis in patients with ESKD specially those with malnutrition. conclusions: We concluded that patients with ESKD has a low level of L‑arginine specially in those with malnutrition and this leads to increase in platelet aggregation and may increase the possibility of thrombus formation in malnourished patients with ESKD. We suggest the use of nutritional supplementation of L‑arginine to suppress this process of atherothrombosis.

Plasma homocysteine level in patients with Behcet's disease with or without thrombosis.

To find the possible role of plasma homocysteine level as a contributing factor in venous and arterial thrombosis in patients with Behcet's disease (BD). In a case control study, two groups of BD patients were included: 47 with thrombosis and 49 without thrombosis. All patients fulfilled the International Study Group Criteria for BD and the confirming diagnostic procedures for vascular thrombosis were either Doppler sonography or angiography. Forty-nine controls were selected by consecutive sampling among age and sex matched healthy subjects. Plasma homocysteine level was measured by ELISA in all. The clinical and laboratory characteristics of the disease were compared between the two groups of BD patients. Comparisons were done by ANOVA and Chi square tests; correlations were analyzed with Pearson test. The mean plasma homocysteine level was significantly higher in BD patients (14.9±13.9 μMol/L) than in healthy controls (9.9±6.7 μMol/L), P<0.02. The difference was also significant when comparing the three groups by ANOVA: BD patients with thrombosis (24.2±13.2 μMol/L), BD patients without thrombosis (5.9±7.0 μMol/L), and healthy controls (P<0.0001). We found no correlation between plasma homocysteine level and any organ involvement other than thrombosis. The mean plasma homocysteine level was lower in HLA-B51 positive BD patients (11.6±12.1 vs. 21.7±16.3 μMol/L, P<0.05), but the difference was not significant in those with thrombosis (20.9±13.2 vs. 29.5±12.7 μMol/L, P=0.18). Hyperhomocysteinaemia may be an independent risk factor for vascular thrombosis in patients with BD. This is the first study showing a negative correlation between HLA-B51 and plasma homocysteine level.

A Case of Huge Thrombus in the Aortic Arch with Cerebrovascular Embolization

Pedunculated thrombus in the aortic arch that is associated with cerebral infarction is very rare requires prompt diagnosis and treatment to prevent occurrence of another devastating complication. Transesophageal echocardiography is useful for detecting source of embolism including aortic thrombi. The treatment options of aortic thrombi involves anticoagulation, thrombolysis, thromboaspiration, and thrombectomy. Here we report a case of huge thrombus in the aortic arch, resulting in acute multifocal cerebellar embolic infarct in patient without any risk factors for vascular thrombosis. Thrombi in the aortic arch were diagnosed by transesophageal echocardiography and treated with anticoagulants successfully.

Lupus nephritis and Raynaud’s phenomenon are significant risk factors for vascular thrombosis in SLE patients with positive antiphospholipid antibodies

This study is aimed to determine the predictors of nongravid vascular thrombosis in systemic lupus erythematosus (SLE) patients with positive antiphospholipid antibodies (SLE-aPL). A cohort of 67 SLE-aPL patients who had at least one positive test for lupus anticoagulant (LA), anticardiolipin (aCL), or anti-beta2glycoprotein-1(B2) was examined. Main outcome was the presence of vascular thrombosis. Association between thrombosis and risk factors was examined by contingency table. The odds ratio (OR) of significant predictors was determined by logistic regression. Three percent of patients were LA(+), 6% were aCL(+), 31% were B2(+), 3% were aCL(+)LA(+), 35.8% were aCL(+)B2(+), 7.5% were LA(+)B2(+), and 13.4% were positive for all tests. As for clinical manifestations, 79% had lymphopenia, 76% had lupus nephritis (LN), 41.8% had autoimmune hemolytic anemia, 34.3% had thrombocytopenia, 20.9% had abortion, and 19.4% had Raynaud's phenomenon (RP). Thrombosis occurred in 26 patients. The prevalence of thrombosis for SLE-aPL was 38.8%. Thrombosis was observed more frequently in patients with LA(+) (12 of 18) than the others (14 of 49; p = 0.01). Two-by-two table showed that oral contraceptive and LN were significantly associated with increased risk of thrombosis, while lymphopenia and antimalarials were significantly associated with decreased risk of thrombosis. Multivariate analysis confirmed that LN and RP were associated with increased risk of thrombosis (OR = 6.2 and 3.2; p = 0.005 and 0.008), while lymphopenia and antimalarials were associated with decreased risk of thrombosis (OR = 0.86 and 0.18; p = 0.02 and 0.034). LA is the strongest test to determine the risk of thrombosis in SLE-aPL. The presence of LN and RP strongly predicts thrombosis, while lymphopenia and antimalarials are protective. These findings help to identify patients who may benefit from prophylactic therapy.

Recovery and Utilization of Deceased Donor Kidneys from Small Pediatric Donors

To the Editor: We appreciate the comments by Dr. Martin et al. on our recent manuscript (1Pelletier SJ Guidinger MK Merion RM et al.Recovery and utilization of deceased donor kidneys from small pediatric donors..Am J Transplant. 2006; 6:: 1646-1652Abstract Full Text Full Text PDF PubMed Scopus (103) Google Scholar). In their letter, they highlight the idea that kidneys from small pediatric deceased donors may be underutilized. We agree that a more aggressive approach to the recovery and utilization of kidneys from this population would be appropriate. They describe some of the technical challenges that may be encountered, particularly with the smallest of donors, which have led some transplant centers to avoid using these grafts. However, as described by Martin et al., many of these difficulties can be overcome and our analysis of national data suggests that excellent graft function can be achieved. Because not all recipient patient populations may benefit equally from en bloc kidney transplantation from small pediatric donors, appropriate recipient selection is important. The North American Pediatric Renal Transplant Cooperative Study demonstrated a considerably increased rate of graft thrombosis for pediatric recipients receiving kidney transplants from donors under 5 years old (2Singh A Stablein D Tejani A Risk factors for vascular thrombosis in pediatric renal transplantation: A special report of the North American Pediatric Renal Transplant Cooperative Study..Transplantation. 1997; 63:: 1263-1267Crossref PubMed Scopus (200) Google Scholar). The current data do not support the transplant of small pediatric donor kidneys into small pediatric recipients. The optimal use of kidneys from small pediatric deceased donors remains unclear. Further studies are needed to determine when kidneys from this donor population should be transplanted individually, benefiting a greater number of recipients, as opposed to transplantation en bloc, where results are maximized for an individual recipient. The Scientific Registry of Transplant Recipients is funded by contract number 231-00-0116 from the Health Resources and Services Administration, U.S. Department of Health and Human Services. The views expressed herein are those of the authors and not necessarily those of the U.S. Government.

α-Galactosidase A Deficiency Leads to Increased Tissue Fibrin Deposition and Thrombosis in Mice Homozygous for the Factor V Leiden Mutation

Factor V Leiden (FVL) is a common genetic risk factor for vascular thrombosis in humans. Fabry disease, an X-linked lysosomal storage disorder attributable to alpha-galactosidase A (GLA) deficiency, is associated with premature vascular events that may be thrombotic in nature. To examine a potential interaction between FvL and Gla deficiency in vivo, we analyzed tissue fibrin deposition in mice carrying combined mutations in FvL and Gla. Gla deficiency markedly increased tissue fibrin deposition in mice carrying the FvL mutation (0.33+/-0.03%; n=7) compared with FvL mutation (0.14+/-0.02%; n=10; P<0.0005). These observations demonstrate a synergistic interaction between Gla deficiency and FvL toward tissue fibrin deposition in mice. Concomitant mutations in these genes may increase the penetrance of vascular thrombotic events in humans.

Differences in the frequency of the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene among the Lebanese population.

In view of its role in precipitating mild hyperhomocysteinemia as well as being a risk factor for vascular thrombosis, we investigated the frequency of the C677T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene among 589 healthy Lebanese subjects by PCR-RFLP analysis (HinfI digestion) and compared them with those of other countries of Caucasian and non-Caucasian origin. The prevalence of the mutated homozygous (T/T) and heterozygous (C/T) C677T MTHFR genotype was 11.04% and 39.73%, respectively, giving an allele frequency of 0.309. While the prevalence of the T/T genotype was similar with respect to gender, higher prevalence was noted among Christian (13.08%) compared to Moslem (7.66%) subjects (P < 0.001), and heterogeneity in its distribution was seen in the different Lebanese provinces, and was directly related to the Christian/Moslem composition of each province. The distribution of the MTHFR C677T in Lebanon is unique with regard to its higher occurrence among Christians compared to Moslems, adding to the existing body of literature on the heterogeneity of its prevalence and distribution.

Pulmonary Fibrosis Is Increased in Mice Carrying the Factor V Leiden Mutation following Bleomycin Injury

Increased fibrin deposition following inflammatory lung injury has been proposed to facilitate the development of pulmonary fibrosis. Therefore, factors predisposing to thrombosis may affect the fibrotic response to injury. Activated protein C (aPC) resistance due to the factor V Leiden mutation (FvL) is a common genetic risk factor for vascular thrombosis. To examine the relationship between aPC resistance and the development of pulmonary fibrosis, lung inflammation was induced by bleomycin in mice carrying the FvL mutation. Three weeks following the instillation of 0.0375 U of bleomycin, the lungs of mice homozygous and heterozygous for FvL contained significantly more hydroxyproline (35 +/- 4 and 36 +/- 7 ug hydroxyproline/mg total protein, respectively) than wild-type mice (26 +/- 6 ug/mg protein, p <0.01 for both comparisons). These data demonstrate a strong relationship between aPC resistance and the pulmonary fibrosis that occurs following inflammatory lung injury.

Risk factors for vascular thrombosis in pediatric renal transplantation: a special report of the North American Pediatric Renal Transplant Cooperative Study.

Vascular thrombosis remains a major cause of graft failure, accounting for 12.2% of failed index transplants and 19.2% of repeat transplants. We conducted a special study to identify the risk factors for vascular thrombosis. A total of 4394 transplants (2060 living donor [LD] transplants and 2334 cadaver donor [CAD] source transplants) were evaluated. The respective vascular thrombosis rates for LD and CAD transplants were 38/2060 (1.8%) and 100/2334 (4.2%) (P<0.001). Univariate analysis showed that the rate of graft loss due to thrombosis was significantly higher in younger children (less than 2 years of age) as compared with older age groups (2-5 years, 6-12 years, and more than 12 years of age) (9.0% vs. 5.5%, 4.4%, and 3.5% for CAD transplant recipients and 3.5% vs. 3.4%, 0.7%, and 1.9% for LD graft recipients). Recipients of kidneys from cadaver donors less than 5 years of age had a significantly higher thrombosis rate (8.3%) than did recipients from older donor groups (5-10 years, 4.5%; greater than 10 years, 3.2%). Recipients of kidneys with cold ischemia time greater than 24 hr also had a higher thrombosis rate (5.6%), as compared with recipients of kidneys with a shorter cold ischemia time (3.2%). Recipients of antilymphocyte therapy on day 0 or day 1 were at dimished risk of graft loss due to thrombosis (2.2% vs. 4.1%, P=0.001). Comparable trends were seen for both LD and CAD organ recipients. LD organ recipients with a history of prior transplantation had a significantly higher rate of thrombosis as compared with those who received a primary transplant (4.6% vs. 1.6%, P=0.005). For both LD and CAD organ recipients, the occurrence of acute tubular necrosis was a significnat risk factor for the development of thrombosis. Regression analysis showed that for LD organ recipients, a history of prior transplantation increased the risk for thrombosis, whereas increasing recipient age had a linear decreasing risk effect. The use of antilymphocyte antibody or cyclosporine on day 0/1 decreased the risk for thrombosis. For CAD kidney recipients, organ cold ischemia time greater than 24 hr increased the risk for thrombosis. The use of antibody induction therapy, donors greater than 5 years of age, and increasing recipient age were factors that decreased the risk for thrombosis.