Predictors of Post-Thrombotic Ulcer after Acute DVT: The RIETE Registry.

In patients with deep-vein thrombosis (DVT) in the lower limbs, venous ulcer is the most debilitating and end-stage clinical expression of the post-thrombotic syndrome (PTS). To date, risk factors for PTS-related ulcer in DVT patients have not been identified.We used the international observational RIETE registry to assess the evolution of PTS signs and symptoms during a 3-year follow-up period and to identify independent predictors of PTS ulcer at 1 year in patients with acute DVT.Among 1,866 eligible patients, cumulative rates of PTS ulcer at 1, 2 and 3 years were 2.7% (n = 50), 4.3% (n = 54) and 7.1% (n = 60), respectively. The proportion of patients with PTS symptoms at 1, 2 or 3 years remained stable (≈40%), while the proportion of patients with PTS signs increased slightly over time (from 49 to 53%). Prior history of venous thromboembolism (VTE) (odds ratio [OR] = 5.5 [2.8-10.9]), diabetes (OR = 2.3 [1.1-4.7]), pre-existing leg varicosities (OR = 3.2 [1.7-6.1]) and male sex (OR = 2.5 [1.3-5.1]) independently increased the risk of PTS ulcer at 1 year. Obesity also increased the risk but failed to reach statistical significance (OR = 1.8 [0.9-3.3]). DVT treatment characteristics (duration or drug) did not influence the risk.Our results evidence that after acute DVT, pre-existing leg varicosities, prior venous thromboembolism, diabetes and male gender independently increased the risk for PTS ulcer. This suggests that clinicians should consider strategies aimed to prevent ulcers in high-risk DVT patients, such as preventing VTE recurrence, use of stockings in those with pre-existing venous insufficiency, careful monitoring of diabetic patients and encouraging weight loss in obese patients.

PREVENTION OF VENOUS THROMBOEMBOLIC COMPLICATIONS IN REPLACEMENT ARTHROPLASTY PERFORMANCE IN PATIENTS WITH ASSOCIATED CHRONIC DISEASES OF LOWER EXTREMITIES VEINS.

A number of patients with problems of major joints increases every year. These patients need the replacement arthroplasty. The rate of thrombotic complications rises in given category of patients simultaneously with the increase of the number of performed operations. There weren't well-defined instructions of management of the patients with associated chronic vein diseases at the preparation period for arthroplasty performance in spite of the presence of clinical recommendations for prevention of thromboembolic complications. The authors analyzed the experience of management of such patients and presented these data for doctors from polyclinic and hospitals in order to apply the common treatment strategy.

How to predict and diagnose postthrombotic syndrome.

Postthrombotic syndrome (PTS) is the most frequent complication of deep vein thrombosis (DVT). From 20% to 50% of the patients will develop PTS after DVT, and from 5% to 10%, severe PTS. PTS is diagnosed on clinical grounds, based on the presence of signs and symptoms of venous insufficiency in the leg ipsilateral to DVT. The Villalta scale, a clinical scale that incorporates venous symptoms and signs, is a recommended standard for the diagnosis of PTS. Identifying which patients are at high risk of developing PTS would help improve the management of patients with DVT and allow physicians to provide patients with individualized information on their expected prognosis. Clinical predictors of PTS have been progressively characterized, but the ability to predict which patient with DVT is likely to develop PTS remains limited. A number of risk factors for PTS have been identified; of these, proximal location of DVT and a previous ipsilateral DVT are the most important. This review discusses the knowledge gained over the last decade on the diagnosis and predictors of PTS.  

The diagnosis and treatment of venous thromboembolism.

Venous thromboembolism (VTE) is a common condition that can lead to complications such as postphlebitic syndrome, chronic pulmonary artery hypertension, and death. The approach to the diagnosis of has evolved over the years and an algorithm strategy combining pretest probability, D-dimer testing, and diagnostic imaging now allows for safe, convenient, and cost-effective investigation of patients. Patients with low pretest probability and a negative D-dimer can have VTE excluded without the need for imaging. The mainstay of treatment of VTE is anticoagulation, whereas interventions such as thrombolysis and inferior vena cava filters are reserved for special situations. Low-molecular-weight heparin has allowed for outpatient management of most patients with deep vein thrombosis at a considerable cost savings to the health care system. Patients with malignancy-associated VTE benefit from decreased recurrent rates if treated with long-term low-molecular-weight heparin. The development of new oral anticoagulants further simplifies treatment. The duration of anticoagulation is primarily influenced by underlying cause of the VTE (whether provoked or not) and consideration of the risk for major hemorrhage. Testing for genetic and acquired thrombophilia may provide insight as to the cause of a first idiopathic deep vein thrombosis, but the evidence linking most thrombophilias to an increased risk of recurrent thrombosis is limited.

Post-thrombotic syndrome: prevention is better than cure.

Post-thrombotic syndrome (PTS) can be debilitating to patients and have a major economic impact on health-care services. It arises after deep venous thrombosis (DVT) due to residual venous obstruction or valvular reflux, leading to increased venous pressure in the microcirculation. While the inflammatory process at the time of DVT may aid thrombus resolution, it may also promote destruction of venous valves. The diagnosis of PTS is principally clinical and patients typically complain of leg heaviness, swelling, pain, itching, cramps, ulcer and signs of lipodermatosclerosis. Several clinical scales or classifications have been used but it is recommended that Villalta scale is the most suitable. Risk factors for PTS include a proximal DVT and recurrent thrombosis as well as obesity and prior varicose veins. Poor quality of anticoagulation control may also be a factor. Established PTS is usually managed along the same lines as chronic venous hypertension with compression therapy and leg elevation. Surgery has only a limited role but may benefit some patients. Further trials are desperately needed to define the role of acute thrombolysis and mechanical thrombectomy, which seem to be promising treatments in the studies to date. For patients who have had a DVT more attention should be given to prescribing and using compression hosiery.

[Treatment of postoperative thrombosis]. / Therapie der postoperativen Thrombose.

For the treatment of deep vein thrombosis (DVT), rapid diagnosis and prompt therapy are crucial to minimize the risk of fatal pulmonary embolism and long-term complications, including the postthrombotic syndrome and recurrent thromboembolism. The treatment of acute DVT remains controversial. In this review, treatment options in relation to exposing and predisposing risk factors are discussed. Evidence-based data and recommendations from official guidelines are presented.

Contemporary issues in the prevention and management of postthrombotic syndrome.

OBJECTIVE: To provide an evidence-based review and clinical summary of postthrombotic syndrome (PTS). DATA SOURCES: A literature review was performed via MEDLINE (1950-July 1, 2009) and International Pharmaceutical Abstracts (1970-June 2009) searches using the terms post-thrombotic syndrome, post-phlebitic syndrome, deep vein thrombosis, and compression stockings. DATA SYNTHESIS: PTS is best characterized as a chronic syndrome of clinical signs and symptoms including pain, swelling, parasthesias, and ulceration in the affected limb following deep vein thrombosis (DVT). It occurs in up to half of patients with symptomatic DVT, usually within the first 2 years. Although the pathophysiology of PTS is not well understood, a thrombus may cause venous hypertension and valvular incompetence resulting in edema, tissue hypoxia, and in severe cases, ulceration. Risk factors for PTS include recurrent ipsilateral DVT, obesity, and poor quality of anticoagulant therapy. PTS diagnosis is based on the presence of typical signs and symptoms and may be made using one of several clinical scoring systems. Prevention of PTS should focus on DVT prevention and the use of elastic compression stockings following DVT, while fibrinolysis remains under investigation as an effective method for PTS prevention. The treatment of PTS may include either pharmacologic or mechanical modalities, although none of these regimens has been rigorously tested. Pharmacists have the opportunity to provide more comprehensive antithrombotic management by educating patients and providers on PTS, recommending appropriate preventive therapy, assisting patients in obtaining and adhering to this therapy, and assisting providers with the management of PTS. CONCLUSIONS: Providers should be proactive in preventing PTS, with pharmacists taking an active role in optimal DVT prevention, identifying patients at risk for PTS, and counseling and directing preventive therapies.

Lower extremities' postthrombotic syndrome after total knee arthroplasty.

BACKGROUND: Deep venous thrombosis (DVT) is a disease associated with high morbidity in 40-60% patients who underwent Total Knee Arthroplasty (TKA). Postthrombotic syndrome (PTS) is a common long-term complication that may develop within 6 months or more than 2 years after episode of DVT. OBJECTIVE: To examine the prevalence of PTS in patients who had history of previous DVT and non-previous DVT at least 2-year follow-up period after TKA. MATERIAL AND METHOD: Retrospective chart review was done. All patients who underwent TKA during October 2002-2005 were included. They were postoperatively assessed for PTS with Villalta score and duplex ultrasonography at > or =2 years. The confirmed diagnosis of DVT was done by contrast venography. RESULTS: 22 of 76 patients (56 previous DVT 20 non-previous DVT) had PTS based on the clinical assessment. The previous-DVT group had significantly higher risk to PTS (OR = 1.59; 95% CI: 1.294-1.949; p-value = 0.001). When diagnosed with duplex ultrasonography, 36 in 56 patients of previous-DVT group and 8 in 20 of non-previous-DVT group were found positive venous reflux. Most of venous reflux occurred at popliteal vein (77%) and posterior tibial vein (59%). CONCLUSION: After TKA, the patients who developed DVT had higher risk to PTS (OR = 1.588). Treatment of DVT may not decrease this risk. Prevention of DVT becomes an important approach to prevent PTS.

Post-thrombotic syndrome in children: a single center experience.

BACKGROUND: Development of post-thrombotic syndrome (PTS) is increasingly being recognized as a complication of deep venous thrombosis (DVT) in children. OBJECTIVE: To determine the prevalence, clinical characteristics, and predictors of moderate to severe PTS in children. METHODS: A retrospective chart review was performed on those children who were followed in the coagulation clinic for objectively confirmed DVTs from December 2004 to December 2006. The scoring system used by Kuhle et al was used to grade the severity of PTS as: mild, moderate, and severe. RESULTS: PTS developed in 20% (11/55; 95% confidence interval 9.4-30.1) of children, in which 8/11 were moderate and 3/11 were severe. Median interval between diagnosis of PTS and DVT was 90 days (range, 46 d to 3 y). The majority (72.7%) of patients in the non-PTS group received treatment intervention within 48 hours of diagnosis of DVT. Delay in treatment initiation (>48 h) and recurrence of DVT were associated with the development of PTS (P<0.05). Variables including occlusive thrombus, location and number of vessels involved with DVT, age at diagnosis, underlying thrombophilia, intensity of anticoagulation, and body mass index were not associated with the development of PTS. Other debilitating consequences of DVT requiring intervention included portal hypertension (n=2), chylothorax (n=1), and reflux sympathetic dystrophy (n=1). The small sample size and limited follow up restricted the statistical analysis. CONCLUSIONS: PTS is a significant problem in children with symptomatic DVTs. Early treatment intervention within the first 48 hours of diagnosis of DVT and prevention of thrombosis recurrence may prevent development of PTS. Although PTS refers to consequences of intravenous hypertension owing to extremity DVTs, sequlae of nonextremity DVTs require special consideration in pediatric PTS classification.

High peak reflux velocity in the proximal deep veins is a strong predictor of advanced post-thrombotic sequelae.

BACKGROUND: The presence of reflux in the femoral vein (FV) and popliteal vein (POPV) after acute deep vein thrombosis (DVT) is considered to contribute to the development of advanced post-thrombotic syndrome (PTS). However, a quantification of reflux has yet to be determined. The purpose of study was to determine the indicative parameters reflecting the progression of PTS. METHODS: Venous abnormalities were evaluated in 131 limbs out of 130 patients who completed a six-year follow-up after an acute DVT. Clinical manifestations were categorized according to the clinical, etiologic, anatomic, and pathophysiologic (CEAP) classification, and the patients were divided into two groups at a six-year follow-up point: group I, C(0-3)E(s),A(s,d,p),P(r,o), early chronic venous insufficiency (CVI); group II, C(4-6)E(s),A(s,d,p),P(r,o), advanced CVI. Venous segments were examined whether they were occluded or recanalized. The reflux parameters assessed were the diameter (cm), the reflux time (RT; s), the peak reflux velocity (PRV; cm s(-1)), and total refluxed volume, and these parameters were assessed especially in the FV and POPV at the two-year (early phase) and subsequent six-year (late phase) follow-up points after DVT. RESULTS: There were 98 limbs in group I and 33 in group II. The frequency of venous reflux was significantly higher in group II (<0.0001). In contrast, the proportion of occlusion did not differ between the groups (P = 0.138). The proportions of FV and POPV incompetence were significantly higher in group II (P < 0.0001 and P < 0.0001, respectively). In these veins, the RT did not improve the discrimination power between the two groups. In contrast, the PRV had significant discrimination power in these veins at both the two- and six-year follow-up points. In the superficial venous system, there were no significant differences in any of the determined parameters between the groups. In group II, 19 patients (58%), who had early symptoms of CVI at the two-year follow-up point, subsequently developed advanced symptoms of PTS. After calculating a suitable cutoff point using receiver operating characteristic curves analysis at the two-year follow-up point, multivariable analysis showed that a PRV of >25.4 cm s(-1) in the POPV was the strongest independent predictor of advanced CVI [odds ratio (OR) 60.32; 95% confidence interval (95CI) 43.1-1238.97, P < 0.0001]. Similarly, in the FV, a PRV of >24.5 cm s(-1) was found to be a strong predictor of advanced CVI (OR 25.77, 95CI 10.56-331.12, P < 0.0001). CONCLUSIONS: These findings suggest that the presence of a high PRV in the proximal deep veins is an independent predictor of advanced symptoms of PTS.

The post-thrombotic syndrome: progress and pitfalls.

The post-thrombotic syndrome (PTS) develops in up to one half of patients after symptomatic deep venous thrombosis (DVT) and is the most common complication of DVT. Typical features of PTS include chronic pain, swelling, heaviness, oedema and skin changes in the affected limb. In severe cases, venous ulcers may develop. The frequency of PTS is likely to be reduced by preventing DVT with the use of effective thromboprophylaxis in high-risk patients and settings and by minimising the risk of ipsilateral DVT recurrence. Use of compression stockings for 2 years after DVT appears to reduce the incidence and severity of PTS but issues remain regarding their use and effectiveness. Future research should focus on elucidating the pathophysiology and risk factors for PTS, assessing the safety and effectiveness of catheter-directed thrombolysis to prevent PTS and evaluating the optimal use of compression stockings to prevent and treat PTS. In addition, new therapies to treat PTS should be sought and evaluated.

Neovalve construction in postthrombotic syndrome.

OBJECTIVE: The purpose of this study was to evaluate a new neovalve construction technique in postthrombotic syndrome. The surgical procedure is described, and preliminary results of the first case series are given. METHODS: From December 2000 to June 2004, neovalve construction in 18 limbs was performed on 16 patients (8 male and 8 female; median age, 55.5 years; range, 34-79 years) to treat severe chronic venous insufficiency in cases of postthrombotic syndrome. Surgical treatment was recommended in cases of nonhealing or recurrent ulcers (CEAP classification class C6). Preoperative duplex scanning, ascending/descending venography, and air plethysmography were routinely performed. Valvular cusps were created by dissecting the thickened venous wall to obtain material with which to fashion a new monocuspid or bicuspid valve. Mean follow-up was 22 months (range, 1-42 months). Postoperative duplex scanning and air plethysmography were performed in all patients. Descending venography was performed after surgery in 15 limbs. RESULTS: In 16 lower extremities (89%), the ulcer healed within 4 to 25 weeks (median, 12 weeks), and no recurrences occurred. Neovalve competence was confirmed in 17 cases (95%). Postoperative duplex scan and air plethysmography showed a significant improvement in hemodynamic parameters (P < .001), especially in younger patients with good muscle pump function. In 17 limbs (95%), the treated segments remained primarily patent at median follow-up of 22 months. Early thrombosis below the neovalve site occurred in two patients (12%). No perioperative pulmonary embolism was observed. A late occlusion occurred in one patient (6%), 8 months after surgery. Minor postoperative complications occurred in three patients (17%). CONCLUSIONS: Neovalve construction seems to be effective in restoring femoral competence in postthrombotic reflux. Although these preliminary results are encouraging, long-term follow-up and a larger series are required to validate the technique.

The post-thrombotic syndrome after upper extremity deep venous thrombosis in adults: a systematic review.

BACKGROUND: Post-thrombotic syndrome is a chronic, potentially debilitating complication of deep vein thrombosis (DVT) of the lower extremity. Comparatively little is known about post-thrombotic syndrome after upper extremity DVT (UEDVT). OBJECTIVE: To perform a systematic review of clinical studies that have examined the incidence, clinical features, risk factors and management of post-thrombotic syndrome after UEDVT. METHODS: Using combinations of keywords venous thrombosis, postphlebitic syndrome, thrombophlebitis, arm swelling, post-thrombotic syndrome, UEDVT, Paget-Schroetter syndrome, thoracic outlet syndrome, axillary vein, subclavian vein, and central venous catheter, the MEDLINE database was searched for English language articles published between January 1967 and December 2004. Retrieval and review of articles were restricted to clinical studies in humans that described long-term outcomes after objectively confirmed UEDVT. RESULTS: Seven studies were reviewed. The frequency of PTS after UEDVT ranges from 7-46% (weighted mean 15%). Residual thrombosis and axillosubclavian vein thrombosis appear to be associated with an increased risk of PTS, whereas catheter-associated UEDVT may be associated with a decreased risk. There is currently no validated, standardized scale to assess upper extremity PTS, and little consensus regarding the optimal management of this condition. Quality of life is impaired in patients with upper extremity PTS, especially after DVT of the dominant arm. CONCLUSIONS: PTS is a frequent complication of UEDVT, yet little is known regarding risk factors and optimal management. A standardized means of diagnosis would help to establish better management protocols. The impact of upper extremity PTS on quality of life should be further quantified.

The post-thrombotic syndrome: incidence and prognostic value of non-invasive venous examinations in a six-year follow-up study.

The ability to predict severity of the post-thrombotic syndrome (PTS) early after acute deep-vein thrombosis (DVT) is limited. The aim of our study was to examine the incidence of PTS prospectively and to evaluate the predictive value of non-invasive venous examinations shortly after DVT for the development of PTS. In 93 patients with DVT thrombosis score (TS), reflux, venous outflow resistance (VOR) and calf muscle pump dysfunction (CMP) were examined prospectively. After one, two and six years patients were evaluated for PTS using the clinical scale of the CEAP-classification (PTS present > or = 3 on a scale from 0 to 6). Area under the curves (AUC) were used to evaluate the predictive value of the non-invasive examinations at one and three months after diagnosis of DVT for future PTS. The cumulative incidence of PTS increased from 49% (32/65) after one year to 55% (36/65) and 56% (27/48) after two and six years, whereas the incidence of patients with PTS class 4 progressed from 20% after two years to 33% after six years. The prognostic value to predict PTS was highest for the combination of TS, VOR and reflux measured three months after diagnosis and showed an AUC of 0.77 (0.65-0.90) for PTS after one year. In conclusion, the incidence of PTS after DVT did not increase significantly after one year, whereas during longer follow-up the severity of PTS rose in patients with PTS. Moreover, measurement of TS, VOR and reflux three months after DVT could predict, with reasonable accuracy, the risk of PTS after one year of follow-up.

Post-thrombotic syndrome after total hip or knee arthroplasty: incidence in patients with asymptomatic deep venous thrombosis.

PURPOSE: To measure the risk of developing signs of post-thrombotic syndrome 15 to 24 months after total hip or knee arthroplasty in patients with asymptomatic deep venous thrombosis (DVT). METHODS: A total of 85 total knee arthroplasty patients and 47 total hip arthroplasty patients were postoperatively screened for asymptomatic DVT using colour duplex ultrasound. RESULTS: The rate of asymptomatic DVT was 37.6% (n = 32) in knee patients and 34.0% (n = 16) in hip patients. All 32 DVT cases in the knee group had thrombi located below the knee, whereas 6 of the 16 DVT cases in the hip group had thrombi located above the knee, the remaining 10 were below the knee. Patients with proximal thrombi were treated with warfarin for 3 months, whereas patients with distal DVT received 300 mg aspirin daily for the same period. All DVT cases were monitored for up to 12 weeks using repeated colour duplex scans. Signs of thrombus resolution were present at around 6 weeks (range, 4-12 weeks). Clot propagation was observed in 3 cases. In a mean of postoperative 18 months (range, 15-24 months), 28 of the 32 knee patients with asymptomatic DVT were available for follow-up: 11 had transient calf and ankle swelling, 6 had persistent oedema, and the remaining 11 were symptom free. 14 of the 16 hip patients with asymptomatic DVT were available for follow-up: 6 had transient calf and ankle swelling, 4 had persistent oedema, and 4 remained symptom free. 17 patients reported ongoing problems and were re-examined. Signs of mild-to-moderate post-thrombotic syndrome were recorded in 4 knee patients and 3 hip patients. CONCLUSIONS: Patients with above-knee DVT were much more likely to have post-thrombotic syndrome. Despite thromboprophylaxis with low-molecular-weight heparin, asymptomatic DVT is common after total joint arthroplasty and is responsible for the development of post-thrombotic venous insufficiency and post-thrombotic syndrome in a considerable proportion of patients. Once symptomatic or asymptomatic DVT is established, treatment appears incapable of preventing the occurrence of post-thrombotic syndrome, especially in cases of above-knee DVT. Efforts should hence concentrate on combating DVT propagation and improving DVT prevention.

Definition of the post-thrombotic syndrome, differences between existing classifications.

BACKGROUND: Accepted diagnostic criteria exist for the diagnosis of deep vein thrombosis (DVT). However, no uniform definition for the diagnosis and treatment of the post-thrombotic syndrome (PTS) exists. We examined the various definitions of PTS that are used and their relationships with invasive venous pressure measurement. METHODS: Patients who had previously suffered a documented DVT underwent clinical evaluation of both lower limbs in which we used five clinical definitions to grade PTS. We included the definition of Widmer, the CEAP classification, the venous clinical severity score (also without compression therapy), and the definitions according to Prandoni and Brandjes in the evaluation. We compared all the clinical scoring systems with invasive ambulatory venous pressure measurement. RESULTS: In total 124 patients were enrolled in whom both legs were evaluated. Thirteen patients had previously suffered bilateral DVT and nine patients had had an ipsilateral recurrent DVT. In the limbs with DVT, 10 (7%) to 29 (21%) were defined as severe PTS, compared to 0-4 (4%) in the control legs. Mild-to-moderate PTS in the DVT legs ranged from 23 to 49%, compared to 13-34% in the control legs. Overall the presence of any PTS in the DVT legs varied from 30% (VCS without compression) to 66% (Brandjes). The scoring systems of Brandjes and VCS showed a tendency towards more legs to be defined as severe PTS. Absolute frequencies of PTS in DVT legs were highest for the classifications according to Widmer, Prandoni and Brandjes. Differences in proportions of any PTS calculated between DVT and control legs varied from 18 to 39%, while odds ratios varied between 2.2 and 5.2 for the different definitions. The CEAP classification and definition of Brandjes show a moderate relation to Widmer, kappa=0.53 and 0.52, respectively. The VCS shows in all comparisons a poor correlation (kappa 0.22-0.41). Prandoni has a moderate correlation with most definitions (kappa 0.40-0.44). CONCLUSION: All clinical definitions of PTS were highly associated with the reference standard of ambulatory venous pressure, with higher AVPs observed in the more severely affected groups. The ability of the scoring systems to discriminate between DVT and control legs as well as the observed prevalence of PTS differed substantially. In part this is due to the considerable overlap in AVP in the different clinical groups, reflecting the fact that our reference standard has substantial deficiencies. No clear advantage was found in any one system of classification over the rest.

Venous disorders: overview of current practice.

Venous disease often is overlooked until the problems it causes become severe. When patients present with concomitant diseases or disorders, those disorders may take priority both in the patient's mind and the caregiver's. Fortunately, there has been an increasing interest in the diagnoses and treatment of venous disorders and with this is a renewed interest in early diagnosis of venous problems and identification of individuals at risk for venous problems.

Predictors of the post-thrombotic syndrome during long-term treatment of proximal deep vein thrombosis.

BACKGROUND: The post-thrombotic syndrome is a chronic, poorly understood complication of deep venous thrombosis (DVT). OBJECTIVES: To evaluate predictors of the post-thrombotic syndrome, including intensity of long-term anticoagulation, and to assess the impact of the post-thrombotic syndrome on quality of life. PATIENTS AND METHODS: The setting was 13 Canadian hospitals and one US hospital. One hundred and forty-five patients with an unprovoked episode of proximal DVT who were initially treated with 3 months of conventional-intensity warfarin [target International Normalized Ratio (INR) of 2.5] then participated in a trial comparing two intensities of long-term warfarin therapy (target INR 2.5 vs. INR 1.7). Post-thrombotic syndrome was assessed at the end of the trial using a validated clinical scale. Generic and venous disease-specific quality of life was compared in patients with and without the post-thrombotic syndrome. Multivariable regression analyses were performed to identify predictors of the post-thrombotic syndrome and of its severity. RESULTS: After an average follow-up of 2.2 years, the prevalence of post-thrombotic syndrome was 37% and of severe post-thrombotic syndrome was 4%. Quality of life was worse in patients with the post-thrombotic syndrome compared with patients who did not have it. The presence of factor (F)V Leiden or the prothrombin gene mutation was an independent predictor of both a lower risk (P = 0.006) and reduced severity (P = 0.045) of the post-thrombotic syndrome. Intensity of anticoagulation did not influence the risk of developing the post-thrombotic syndrome. CONCLUSIONS: The post-thrombotic syndrome is a frequent and burdensome complication of proximal DVT, even among patients maintained on long-term oral anticoagulation. While the presence of FV Leiden or prothrombin gene mutation appears to be associated with a reduced risk of post-thrombotic syndrome, this finding requires further evaluation in prospective studies.