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Susan R Kahn

Publications and source records attributed to Susan R Kahn.

34 records · Page 2Linked to original sources
PubMed2004

A cost-effectiveness analysis of fondaparinux sodium compared with enoxaparin sodium as prophylaxis against venous thromboembolism: use in patients undergoing major orthopaedic surgery.

OBJECTIVE: To determine the cost effectiveness of fondaparinux sodium compared with enoxaparin sodium for prophylaxis against venous thromboembolism in patients undergoing major orthopaedic surgery. METHODS: Using a cohort simulation model, two primary analyses were conducted from the perspective of the US healthcare payer. Probabilities for a trial-based analysis were obtained from patients participating in the fondaparinux clinical trial programme supplemented with data from published literature. Probabilities for a label-based analysis were estimated for a hypothetical cohort of US patients receiving either fondaparinux or enoxaparin as recommended by US FDA-approved labelling. Resource use and costs were obtained from large US healthcare databases. Outcome measures were rates of symptomatic thromboembolic events and healthcare costs. Costs were in 2003 values. RESULTS: In the trial-based analysis, fondaparinux was estimated to prevent 15.1 symptomatic venous thromboembolic events (per 1,000 patients) at 3 months for patients undergoing major orthopaedic surgery compared with enoxaparin. The cost savings (per patient) of using fondaparinux over enoxaparin are US 61 dollars at 30 days, US 89 dollars at 3 months, and US 155 dollars at 5 years. In the label-based analysis, fondaparinux was estimated to prevent 17.8 venous thromboembolic events (per 1,000 patients) at 3 months compared with enoxaparin, producing savings per patient of US 25 dollars at discharge, US 112 dollars over 1 month, US 141 dollars over 3 months and US 234 dollars over 5 years. Results remain robust to clinically plausible variation in input parameters and assumptions. CONCLUSION: Our model suggests that fondaparinux, when compared with the current standard regimen of enoxaparin for prophylaxis of venous thromboembolism in major orthopaedic surgery, improves outcomes and is cost saving from a US healthcare-payer perspective over the broad range of assumptions evaluated.

Aged↗
PubMed2004

Pharmacoeconomic analysis of fondaparinux versus enoxaparin for the prevention of thromboembolic events in orthopedic surgery patients.

INTRODUCTION: Fondaparinux is a novel synthetic antithrombotic that has been evaluated for the prevention of venous thromboembolism (VTE). In four large trials in patients who underwent major hip or knee surgery, fondaparinux was found to have a good safety profile and be more effective than enoxaparin. To generate Canadian pharmacoeconomic data for fondaparinux, an internationally developed cohort deterministic model was used to estimate the costs and consequences of prophylaxis with fondaparinux compared with enoxaparin in the Canadian orthopedic surgical setting. DESIGN AND SETTING: A health economic advisory group was assembled to guide the pharmacoeconomic evaluation. Efficacy and safety data for fondaparinux relative to enoxaparin were abstracted from a meta-analysis of four randomized trials. Canadian cost data to populate the model were obtained from a resource-use survey of four large Canadian hospitals, from the Canadian Institute for Health Information (CIHI), and from the Canadian economic literature. Case-mix information obtained from CIHI was incorporated into the cohort deterministic model, which predicted the number of VTEs and bleeds following prophylaxis with fondaparinux or enoxaparin within 90 days of surgery, and the associated overall cost difference. The stability of the base-case findings was evaluated with sensitivity analyses. STUDY PERSPECTIVE: Canadian healthcare system perspective. MAIN OUTCOME MEASURES AND RESULTS: Assuming a case mix of 50,693 major hip or knee surgeries performed in Canada in 1999/2000 (as reported by CIHI), the model predicted that prophylaxis with fondaparinux would avoid an additional 16 symptomatic VTEs per 1000 patients over the first 90 days, with an average cost savings of Can 55 dollars per patient. These findings were stable when key economic and clinical parameters were varied, including bleeding events. CONCLUSIONS: Our results suggest that in Canada, prophylactic fondaparinux compared with enoxaparin avoids VTEs and is associated with lower costs in patients who undergo major hip or knee surgery.

Anticoagulants↗
PubMed2003

Markers of coagulation and angiogenesis in cancer-associated venous thromboembolism.

PURPOSE: We sought to determine whether venous thromboembolism in cancer patients is associated with aberrant plasma levels of hemostatic and angiogenic factors. PATIENTS AND METHODS: Peripheral blood was collected before anticoagulant therapy from cancer patients with acute deep venous thrombosis (DVT; DVT + cancer group, n = 32), those without DVT (cancer control group, n = 36), and patients with acute DVT but no cancer (DVT control group, n = 58). Plasma assays of activation and inhibition of coagulation and fibrinolysis, as well as angiogenesis activation, were then performed. RESULTS: Median levels of thrombin-antithrombin complex, prothrombin fragments 1 + 2, and von Willebrand factor antigen were significantly greater in the DVT + cancer group than in the cancer control and DVT control groups (17.8 ng/mL v 4.6 ng/mL and 9.8 ng/mL, P =.0001 and P =.003, respectively; 3.65 nmol/L v 1.60 nmol/L and 2.71 nmol/L, P <.0001 and P =.011, respectively; and 4.04 U/mL v 2.26 U/mL and 2.06 U/mL, P <.0001, respectively). Median levels of tissue-type plasminogen activator were also significantly higher, while protein C activity was lower in the DVT + cancer group than in the DVT control group (14.6 ng/mL v 9.50 ng/mL, respectively, P =.0005; 0.89 U/mL v 1.11 U/mL, respectively, P =.0008). CONCLUSION: These data not only support prior observations of coagulation activation in patients with malignancy, but also provide new evidence for enhanced coagulation activation in the setting of acute venous thromboembolism in cancer. Future prospective studies are warranted to determine whether these and other potential markers of hypercoagulability may help to identify cancer patients at highest risk for venous thromboembolism.

Biomarkers↗
PubMed2003

Comparison of low-intensity warfarin therapy with conventional-intensity warfarin therapy for long-term prevention of recurrent venous thromboembolism.

BACKGROUND: Warfarin is very effective in preventing recurrent venous thromboembolism but is also associated with a substantial risk of bleeding. After three months of conventional warfarin therapy, a lower dose of anticoagulant medication may result in less bleeding and still prevent recurrent venous thromboembolism. METHODS: We conducted a randomized, double-blind study, in which 738 patients who had completed three or more months of warfarin therapy for unprovoked venous thromboembolism were randomly assigned to continue warfarin therapy with a target international normalized ratio (INR) of 2.0 to 3.0 (conventional intensity) or a target INR of 1.5 to 1.9 (low intensity). Patients were followed for an average of 2.4 years. RESULTS: Of 369 patients assigned to low-intensity therapy, 16 had recurrent venous thromboembolism (1.9 per 100 person-years), as compared with 6 of 369 assigned to conventional-intensity therapy (0.7 per 100 person-years; hazard ratio, 2.8; 95 percent confidence interval, 1.1 to 7.0). A major bleeding episode occurred in nine patients assigned to low-intensity therapy (1.1 events per 100 person-years) and eight patients assigned to conventional-intensity therapy (0.9 event per 100 person-years; hazard ratio, 1.2; 95 percent confidence interval, 0.4 to 3.0). There was no significant difference in the frequency of overall bleeding between the two groups (hazard ratio, 1.3; 95 percent confidence interval, 0.8 to 2.1). CONCLUSIONS: Conventional-intensity warfarin therapy is more effective than low-intensity warfarin therapy for the long-term prevention of recurrent venous thromboembolism. The low-intensity warfarin regimen does not reduce the risk of clinically important bleeding.

Age Factors↗
PubMed2003

Thrombophilic disorders and fetal loss: a meta-analysis.

BACKGROUND: Our aim was to assess the strength of the controversial association between thrombophilia and fetal loss, and to examine whether it varies according to the timing or definition of fetal loss. METHODS: We searched Medline and Current Contents for articles published between 1975 and 2002 and their references with terms denoting recurrent fetal and non-recurrent fetal loss combined with various thrombophilic disorders. We included in our meta-analysis case-control, cohort, and cross-sectional studies published in English, the methodological quality of which was rated as moderate or strong. Pooled odds ratios (OR) with 95% CI were generated by random effects models with Cochrane Review Manager software. FINDINGS: We included 31 studies. Factor V Leiden was associated with early (OR 2.01, 95% CI 1.13-3.58) and late (7.83, 2.83-21.67) recurrent fetal loss, and late non-recurrent fetal loss (3.26, 1.82-5.83). Exclusion of women with other pathologies that could explain fetal loss strengthened the association between Factor V Leiden and recurrent fetal loss. Activated protein C resistance was associated with early recurrent fetal loss (3.48, 1.58-7.69), and prothrombin G20210A mutation with early recurrent (2.56, 1.04-.29) and late non-recurrent (2.30, 1.09-4.87) fetal loss. Protein S deficiency was associated with recurrent fetal loss (14.72, 0.99-218.01) and late non-recurrent fetal loss (7.39, 1.28-42.63). Methylenetetrahydrofolate mutation, protein C, and antithrombin deficiencies were not significantly associated with fetal loss. INTERPRETATION: The magnitude of the association between thrombophilia and fetal loss varies, according to type of fetal loss and type of thrombophilia.

Abortion, Habitual↗
PubMed2003

Evaluation of outcomes in chronic venous disorders of the leg: development of a scientifically rigorous, patient-reported measure of symptoms and quality of life.

OBJECTIVE: The purpose of this study was to develop a practical and scientifically rigorous, patient-reported outcome measure to evaluate quality of life and symptoms across the range of conditions (eg, telangiectasias, varicose veins, edema, skin changes, leg ulcers) in chronic venous disorders of the leg (CVDL). METHODS: This study was a psychometric study within the VEnous INsufficiency Epidemiological and Economic Study (VEINES), an international, prospective cohort study to evaluate clinical outcomes, quality of life, costs, and use of health services in CVDL. The study was set in the 166 general practices and 116 specialist clinics in Belgium, France, Italy, and Canada (Quebec) that participated in the VEINES study plus in additional specialist clinics in Ottawa and Montreal. Field testing was carried out in three samples of patients in four countries (Belgium, France, Italy, Canada), including participants in the VEINES study (n dagger 1531) and patients recruited in additional samples of 88 English-speaking patients (Canada) and 53 French-speaking patients (Belgium, France). The reliability and validity sample (n = 615) included 527 VEINES patients and 88 patients from the supplementary English-speaking sample. The test-retest sample (n = 135) included 53 French-speaking and 82 English-speaking patients from the supplementary samples. The responsiveness sample included 1516 VEINES patients. The 26-item VEINES-QOL/Sym is a new, patient-reported questionnaire to evaluate symptoms and quality of life and is available in four language versions (English, French, Italian, French Canadian). RESULTS: Standard psychometric tests confirmed the acceptability (missing data, item endorsement frequencies, floor and ceiling effects), reliability (internal consistency, item-total, inter-item correlations) and validity (content, construct, convergent, discriminant, known groups) of the four language versions of the VEINES-QOL/Sym and the test-retest reliability of the English and French versions and provided preliminary evidence of responsiveness in a pooled language sample. CONCLUSION: The VEINES-QOL/Sym is a practical and scientifically sound, patient-reported measure of outcomes in CVDL that has been developed with rigorous methods. As the only fully validated measure of quality of life and symptoms that is appropriate for use across the full spectrum of CVDL-related conditions, that is quick and easy to administer, and that is available in four languages, the VEINES-QOL/Sym provides a rigorous tool for improving the evaluation of outcomes in clinical trials, epidemiologic studies, and audit.

Adult↗
PubMed2003

Acute effects of exercise in patients with previous deep venous thrombosis: impact of the postthrombotic syndrome.

BACKGROUND: The postthrombotic syndrome (PTS) occurs frequently after deep venous thrombosis (DVT) and is believed to worsen with upright posture and physical activity. However, the effects of exercise in patients with previous DVT have not been studied. STUDY OBJECTIVES: To determine whether previous DVT and PTS limit the ability to exercise, and whether exercise increases the severity of venous symptoms and signs. DESIGN AND SETTING: A repeated-measures cohort study that was conducted at a university-affiliated teaching hospital, 1999-2000. PARTICIPANTS: Subjects with a first episode of unilateral DVT at least 1 year earlier were recruited from the Thrombosis Clinic (total, 41 subjects; with PTS, 19 subjects). INTERVENTION: Treadmill exercise session. MEASUREMENTS AND RESULTS: Venous symptoms, calf muscle fatigability, flexibility, and leg volume before and after treadmill exercise were measured and compared. Exercise did not worsen venous symptoms, despite a higher gain in affected leg volume in subjects with PTS vs subjects without PTS (mean difference: affected leg, 53 mL; unaffected leg, -15 mL; p = 0.018). Calf flexibility significantly improved after exercise in subjects with PTS (gastrocnemius: affected-unaffected, PTS vs no PTS + 4.5 degrees, p = 0.0029; soleus: affected-unaffected, PTS vs no PTS + 5.7 degrees, p = 0.0011). CONCLUSIONS: Exercise did not acutely exacerbate symptoms and, in subjects with PTS, resulted in improved flexibility in the affected leg. Our findings suggest that treadmill or similar exercise is unlikely to make symptoms of PTS worse, and may improve flexibility. Further study is indicated to determine whether a regular exercise-training program might have a role in the management of patients with PTS, since, to date, the treatment options for this condition are limited.

Adult↗
PubMed2003

The economics of venous thromboembolism prophylaxis: a primer for clinicians.

Cost-effectiveness information can help health-system participants make decisions about diagnostic or therapeutic innovations that are more expensive but incrementally safe and effective. However, these analyses cannot help decide whether a less expensive approach is "sufficient" and funds ought to be allocated to other medical issues entirely. At present, formulary committees are commonly determining that medications are "mostly equivalent" in efficacy and safety and choosing individual medications or classes of medications based on cost. Clinicians may not agree with these decisions and will need to understand their rationale. For prophylaxis of venous thromboembolism after hip and knee replacement and hip fracture surgery, many preventive modalities are available with different safety and efficacy profiles and different costs. It is possible to list the important safety and efficacy outcomes of prophylaxis, estimate their incidences and costs, and "model" comparisons of one modality vs another, in order to help decide whether one is preferable.

Anticoagulants↗
PubMed2003

Measuring the outcomes and pharmacoeconomic consequences of venous thromboembolism prophylaxis in major orthopaedic surgery.

Patients who have undergone orthopaedic surgery represent a high-risk group for venous thromboembolism (VTE). Despite the routine prophylactic use of antithrombotic agents, patients still experience thrombotic events that can result in mortality and acute morbidity and, in significant numbers of patients, may lead to long-term consequences such as the post-thrombotic syndrome. Increasingly, initial VTE events occur after hospital discharge since the length of stay in hospital after major orthopaedic surgery has decreased in many countries. There is a need for further improvement in the prevention of VTE. As well as undergoing extensive safety and efficacy studies for registration purposes, new prophylactic strategies need to be evaluated from a pharmacoeconomic perspective to help guide their introduction into routine clinical practice. Over the past 15 years a number of pharmacoeconomic evaluation studies of VTE prophylaxis have been carried out in orthopaedic patients, most of which evaluated short-term clinical endpoints. During the same period, improvements in our understanding of the natural history of VTE as well as the emergence of new treatments have led to changes in the management of patients with, or at risk of, VTE. The aim of this paper was to address how best to conduct pharmacoeconomic analyses of new antithrombotic agents in light of changes in practice patterns for orthopaedic patients and greater understanding of the disease process. We put forward recommendations for relevant outcome measures, timeframes, endpoints and epidemiologic data sources. We also suggest a structure for a pharmacoeconomic model. In this model, the outcomes and costs of VTE-related care during both the acute and chronic phases of the disease are incorporated. Symptomatic deep vein thrombosis and pulmonary embolism, recurrent VTE, post-thrombotic syndrome, major hemorrhage and all-cause death are included. We also recommend that the relevance of quality-adjusted survival is investigated, and that economic appraisals are presented in both cost-consequence and budget-impact approaches. These recommendations are based on extensive examination of recent advances in the management of VTE combined with a greater understanding of its natural history.

Anticoagulants↗
PubMed2002

The epidemiology of peripheral vein infusion thrombophlebitis: a critical review.

We critically assessed studies on the clinical importance, diagnosis, incidence, and pathogenesis of peripheral vein infusion thrombophlebitis, including catheter-related and patient-related risk factors. We reviewed the evidence linking thrombosis, particularly prothrombotic states such as the inherited thrombophilic disorders, with peripheral vein infusion thrombophlebitis. Peripheral vein infusion thrombophlebitis occurs in 25% to 35% of hospitalized patients with peripheral intravenous catheters and has both patient-related implications (e.g., sepsis) and economic consequences (e.g., extra nursing time). Although duration of catheterization, catheter-related infection, and catheter material are important risk factors for peripheral vein infusion thrombophlebitis, patient-related risk factors are not well elucidated.

Catheterization, Peripheral↗
PubMed2002

Effect of postthrombotic syndrome on health-related quality of life after deep venous thrombosis.

BACKGROUND: Postthrombotic syndrome (PTS) is a frequent chronic complication of deep venous thrombosis, yet its impact on health-related quality of life has not been well characterized. We compared generic and venous disease-specific quality of life in patients with and without PTS, and assessed whether quality of life correlated with severity of PTS. METHODS: Subjects with previous deep venous thrombosis were participants in a study of the effects of exercise after deep venous thrombosis. We ascertained PTS and its severity using a validated clinical scale. Subjects completed generic (the 36-Item Short-Form Health Survey) and disease-specific (Venous Insufficiency Epidemiologic and Economic Study quality-of-life questionnaire [VEINES-QOL] and its validated subscale of 10 items on venous symptoms [VEINES-Sym]) quality-of-life measures. Age- and sex-adjusted mean quality-of-life scores were compared in patients with and without PTS, and by severity of PTS. RESULTS: Of the 41 subjects (mean age, 51.2 years), 19 (46%) had PTS. Subjects with PTS had significantly worse disease-specific quality-of-life scores than those without PTS (mean +/- SD VEINES-QOL score, 44.5 +/- 11.6 vs 54.8 +/- 5.4, respectively [P<.001]; mean +/- SD VEINES-Sym score, 45.6 +/- 11.4 vs 54.1 +/- 6.7, respectively [P =.003]), which worsened significantly with increasing severity of PTS. We found no differences in generic quality-of-life scores between subject groups. CONCLUSIONS: Postthrombotic syndrome has a significant impact on disease-specific quality of life that may not be captured by generic quality-of-life measures. Patient-based quality-of-life measures correlated well with physician-assessed PTS. Further research is indicated to assess the value of including quality of life as a routine measure of outcome in clinical studies of patients with deep venous thrombosis and PTS.

Analysis of Variance↗
PubMed2002

The post-thrombotic syndrome: current knowledge, controversies, and directions for future research.

The post-thrombotic syndrome (PTS) is a long-term complication of deep venous thrombosis (DVT) that is characterized by chronic, persistent pain, swelling and other signs in the affected limb. PTS is common, burdensome and costly. It is likely to increase in prevalence, since despite widespread use of and improvements in the efficacy of thromboprophylaxis, the incidence of DVT has not decreased over time. About 20-50% of patients develop PTS within 1-2 years of symptomatic DVT, and severe PTS, which can include venous ulcers, occurs in 5-10% of cases. Although there is no gold standard for the diagnosis of PTS, the presence of typical clinical features in a patient with previous DVT provides strong supporting evidence. Objective evidence of venous valvular incompetence helps to confirm the diagnosis in symptomatic patients. Preventing ipsilateral recurrence of DVT, by ensuring an adequate duration and intensity of anticoagulation for the initial DVT and by prescribing situational thromboprophylaxis after discontinuation of oral anticoagulants, is likely to reduce the risk of developing PTS. There is no proven role for thrombolysis of the initial DVT to prevent PTS. Daily use of graduated compression stockings after DVT may reduce the risk of PTS, and may prevent worsening of established PTS. Pending the results of ongoing studies, stockings are recommended in patients with persistent symptoms or swelling after DVT. Future research should focus on standardizing criteria for PTS diagnosis, identification of DVT patients at high risk for PTS, and rigorously evaluating the effectiveness of stockings, thrombolysis, and venoactive drugs in preventing or treating PTS.

Disease Management↗
PubMedDate not supplied

Risk factors for the first-time development of venous ulcers of the lower limbs: the influence of heredity and physical activity.

The objective of this prospective case-control study was to identify and quantify demographic and clinical risk factors for venous ulcer disease, with special emphasis on heredity and physical activity. Patients presenting to a participating vascular surgery department between January and December 1997 with a first open venous ulcer served as cases. Controls were sampled among patients with subacute conditions such as skin problems, back pain, cold, headache/migraine, sore throat, and mild ear infections and were matched on referral physician, age (+/-5 years), and gender. Subjects were eligible if they were 18 years or older and were excluded if they had nonpalpable pedal pulse or any chronic active diseases such as cancer or AIDS. Cases' and controls' statuses were ascertained by the participating physicians. Data on risk factors were collected with an interviewer-administered questionnaire and were self-reported by patients. The mean age of participants was 61 years for cases (n = 102) and 59 years for controls (n = 200). Family history of maternal venous insufficiency (odds ratio (OR) = 6.8, 95% confidence interval (CI) = [1.9, 24.3]95%), vigorous exercise (OR = 8.9, CI = [1.1, 72.0]95%), and history of deep vein thrombosis (DVT) (OR = 17.6, CI = [2.9, 106.8]95%) were found to be significant predictors of venous ulcers in matched multivariate logistic regression analysis; number of pregnancies was also a significant risk factor in women (OR = 1.2, Cl = [1.0, 1.5]95%). Our study suggests that knowledge of family history of venous insufficiency and monitoring of physical activity will lead to ulcer prevention. Although physical activity is recommended for patients with venous insufficiency, vigorous exercise increases the likelihood of ulcerations.

Case-Control Studies↗