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Biomedical subjects

G E Raskob

Publications and source records attributed to G E Raskob.

At least 19 recordsLinked to original sources
PubMed2000

Predictive value of compression ultrasonography for deep vein thrombosis in symptomatic outpatients: clinical implications of the site of vein noncompressibility.

BACKGROUND: Compression ultrasonography has a high negative predictive value for deep vein thrombosis in symptomatic outpatients. Limited data are available on factors influencing positive predictive value. The objective of this study was to evaluate the positive predictive value of compression ultrasonography according to the anatomic site of vein noncompressibility. METHODS: We performed a prospective cohort study of 756 consecutive outpatients with suspected first-episode deep vein thrombosis. Compression ultrasonography was performed at the initial visit: results were abnormal if a noncompressible segment was identified or normal if all segments were fully compressible. Venography was performed in patients with abnormal compression ultrasonography results. Positive predictive value was determined according to the site of noncompressibility: common femoral vein only, popliteal vein only, or both sites. Venography was the reference standard for the presence of deep vein thrombosis. RESULTS: Positive predictive value was 16.7% (95% confidence interval, 0.4%-64.1%) for noncompressibility isolated to the common femoral vein compared with 91.3% (95% confidence interval, 72.0%-98.9%) for the popliteal vein only and 94.4% (95% confidence interval, 72.7%-99.9%) for both sites (P<.001). Of 15 patients with isolated noncompressibility of the common femoral vein, 8 (53%) had pelvic neoplasm or abscess compared with 2 (5%) of 42 with noncompressibility of the popliteal vein only and 6 (13%) of 47 with noncompressibility of both sites (P<.001). CONCLUSIONS: The positive predictive value of noncompressibility isolated to the common femoral vein is too low to be used alone as the diagnostic end point for giving anticoagulant therapy. Noncompressibility isolated to the common femoral vein is a diagnostic marker for pelvic disease.

Adult↗
PubMed2000

Sensitivity and specificity of helical computed tomography in the diagnosis of pulmonary embolism: a systematic review.

PURPOSE: To determine the sensitivity and specificity of helical computed tomography (CT) for the diagnosis of pulmonary embolism and to determine the safety of withholding anticoagulant therapy in patients who have clinically suspected pulmonary embolism and negative results on helical CT. DATA SOURCES: The MEDLINE database was searched for all reports published from 1986 to October 1999 that evaluated the use of helical CT for the diagnosis of pulmonary embolism. Bibliographies of the retrieved articles were cross-checked to identify additional studies. STUDY SELECTION: All prospective English-language studies were selected. Retrospective studies, review articles, and case reports were excluded, and 5 of the 20 identified articles were excluded. The scientific validity of the remaining 15 articles was assessed. DATA EXTRACTION: Two of the authors used a priori, pre-defined criteria to independently assess each study. A third author resolved disagreements by adjudication. The pre-defined criteria were inclusion of a consecutive series of all patients with suspected pulmonary embolism, inclusion of patients with and those without pulmonary embolism, a broad spectrum of patient characteristics, performance of helical CT and pulmonary angiography (or an appropriate reference test) in all patients, and independent interpretation of the CT scan and pulmonary angiogram (or reference test). Specific data on sensitivity and specificity and the associated 95% CIs were recorded when available. DATA SYNTHESIS: No study met all of the predefined criteria for adequately evaluating sensitivity and specificity. The reported sensitivity of helical CT ranged from 53% to 100%, and specificity ranged from 81% to 100%. In no prospective study was anticoagulant therapy withheld without further testing for venous thromboembolism in consecutive patients with suspected pulmonary embolism. One prospective study reported the outcome of selected patients with negative results on helical CT who did not receive anticoagulant therapy. CONCLUSIONS: Use of helical CT in the diagnosis of pulmonary embolism has not been adequately evaluated. The safety of withholding anticoagulant treatment in patients with negative results on helical CT is uncertain. Definitive large, prospective studies should be done to evaluate the sensitivity, specificity, and safety of helical CT for diagnosis of suspected pulmonary embolism.

Anticoagulants↗
PubMed2000

Low-molecular-weight heparin vs heparin in the treatment of patients with pulmonary embolism. American-Canadian Thrombosis Study Group.

BACKGROUND: Pulmonary embolism (PE) occurs in 50% or more of patients with proximal deep-vein thrombosis. Low-molecular-weight heparin treatment is effective and safe in patients with deep vein thrombosis and may also be so in patients with PE. Recent rigorous clinical trials have established objective criteria for determining a high probability of PE by perfusion lung scanning. OBJECTIVE: To compare low-molecular-weight heparin with intravenous heparin for the treatment of patients with objectively documented PE and underlying proximal deep vein thrombosis. METHODS: In a multicenter, double-blind, randomized trial, we compared fixed-dose subcutaneous low-molecular-weight heparin (tinzaparin sodium) given once daily with dose-adjusted intravenous heparin given by continuous infusion using objective documentation of clinical outcomes. Pulmonary embolism at study entry was documented by the presence of high-probability lung scan findings. RESULTS: Of 200 patients with high-probability lung scan findings at study entry, none of the 97 who received low-molecular-weight heparin had new episodes of venous thromboembolism compared with 7 (6.8%) of 103 patients who received intravenous heparin (95% confidence interval for the difference, 1.9%-11.7%; P = .01). Major bleeding associated with initial therapy occurred in 1 patient (1.0%) who was given low-molecular-weight heparin and in 2 patients (1.9%) given intravenous heparin (95% confidence interval for the difference, -2.4% to 4.3%). CONCLUSIONS: Low-molecular-weight heparin administered once daily subcutaneously was no less effective and probably more effective than use of dose-adjusted intravenous unfractionated heparin for preventing recurrent venous thromboembolism in patients with PE and associated proximal deep vein thrombosis. Our findings extend the use of low-molecular-weight heparin without anticoagulant monitoring to patients with submassive PE.

Adolescent↗
PubMed2000

Withholding treatment in patients with acute pulmonary embolism who have a high risk of bleeding and negative serial noninvasive leg tests.

PURPOSE: Patients who have nonmassive acute pulmonary embolism and a high risk of bleeding or contraindication to anticoagulants, such recent surgery or gastrointestinal bleeding, present a clinical dilemma. We sought to estimate whether such patients could be safely left untreated if serial compression ultrasound or serial impedance plethysmography were negative and cardiorespiratory reserve was adequate. SUBJECTS AND METHODS: The frequency of recurrent pulmonary embolism among patients with nonmassive acute pulmonary embolism and negative serial noninvasive leg tests who were not treated was estimated from two prospective studies of the noninvasive management of patients with suspected pulmonary embolism. One of the studies used serial impedance plethysmography of the lower extremities; the other used serial compression ultrasound. The prevalence of pulmonary embolism in patients with nondiagnostic ventilation/perfusion lung scans was determined from the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). RESULTS: The estimated frequency of fatal recurrent pulmonary embolism was 1% [95% confidence interval (CI), 0% to 5%) among untreated patients with nonmassive pulmonary embolism who had negative serial impedance plethysmograms and 0% (95% CI, 0% to 4%) among those with negative serial compression ultrasonograms. The frequency of nonfatal recurrent pulmonary embolism among untreated patients was 3%, regardless of whether they had negative serial impedance plethysmograms or negative serial compression ultrasonograms. These results were comparable with the frequency of recurrent pulmonary embolism among patients treated with anticoagulants or with inferior vena cava filters. CONCLUSION: Withholding treatment of nonmassive acute pulmonary embolism, if serial impedance plethysmograms or serial venous ultrasonograms are negative and cardiopulmonary reserve is adequate, is a possible strategy for the management of patients with a high risk of bleeding or other contraindication to anticoagulants. This strategy may be associated with fewer adverse events than treatment with anticoagulants or an inferior vena cava filter. Prospective trials comparing alternative treatments are needed.

Acute Disease↗
PubMed1999

Preoperative vs postoperative initiation of low-molecular-weight heparin prophylaxis against venous thromboembolism in patients undergoing elective hip replacement.

BACKGROUND: Although preoperative and postoperative initiation of prophylaxis for deep vein thrombosis (DVT) with low-molecular-weight heparin (LMWH) are effective, the relative effectiveness and safety of these approaches is unknown. In the absence of a published definitive level 1 trial addressing this question, a meta-analysis is appropriate. OBJECTIVE: To report a meta-analysis comparing preoperative with postoperative initiation of prophylaxis of DVT in patients undergoing elective hip replacement. METHODS: Relevant trials were identified, and potential biases in the meta-analysis were minimized by analyzing all rigorously performed randomized trials that met all of the following criteria for conduct of the trial: (1) double-blind design, (2) objective documentation of the frequencies of DVT by ascending contrast venography, (3) venography performed before or at the time of discharge from the hospital, (4) initiation of the same LMWH preoperatively or postoperatively in dosages shown to be effective, (5) compliance with the criteria for a level 1 trial, and (6) objective documentation of major and minor bleeding according to strict criteria. RESULTS: Treatment with LMWH initiated preoperatively was associated with a DVT frequency of 10.0% compared with a frequency of 15.3% when the LMWH was initiated postoperatively (P = .02, Fisher exact test). Major bleeding was less frequent in patients receiving preoperatively initiated LMWH than in patients receiving postoperatively initiated LMWH (0.9%, vs. 3.5%; P = .01, Fisher exact test). CONCLUSIONS: Our findings support the need for a randomized comparison of preoperative and postoperative initiation of pharmacological prophylaxis of DVT. Such a trial would resolve the divergent practices for DVT prophylaxis between Europe and the North American countries, the United States and Canada, and would affect the treatment for thousands of patients on both continents.

Anticoagulants↗
PubMed1999

Diagnosis of pulmonary embolism.

The patient with suspected pulmonary embolism presents a challenging diagnostic problem. The symptoms and signs are nonspecific, and objective testing is required to establish or exclude the presence of pulmonary embolism. Lung scanning continues to be a first-line test, but in 40% to 70% of all patients, the results do not definitively provide indication for either giving or withholding anticoagulant treatment even when combined with the clinical assessment. Pulmonary angiography is the reference standard, but it is invasive and may not be available in all clinical settings. Pulmonary embolism is strongly associated with proximal deep-vein thrombosis of the legs (popliteal, femoral, or iliac vein thrombosis). Objective testing for proximal deep-vein thrombosis is useful in patients with suspected pulmonary embolism. A positive result from such testing provides an indication for anticoagulant treatment. Serial testing for proximal deep-vein thrombosis is a safe and effective alternative to pulmonary angiography in patients with adequate cardiorespiratory reserve. The assay for plasma D-dimer using either a rapid enzyme-linked immunospecific assay technique or a bedside whole-blood agglutination technique is promising as a test for excluding venous thromboembolism. A positive result by spiral CT imaging is useful for ruling in a diagnosis of pulmonary embolism, but the safety of withholding treatment in patients with negative spiral CT results remains uncertain. Pulmonary angiography continues to have an important role in selected patients in whom it is critical to definitively confirm or exclude the presence of pulmonary embolism.

Humans↗
PubMed1999

Drug-induced thrombocytopenia.

Many drugs can induce thrombocytopenia mediated by drug-dependent antiplatelet antibodies. Recent studies have documented specific epitopes for drug-dependent antibody binding on glycoprotein Ib-IX, glycoprotein IIb-IIIa, and platelet-endothelial cell adhesion molecule-1. Molecular identification of antibody binding sites may help to identify susceptible individuals. Management of patients with unexpected thrombocytopenia who are taking multiple drugs remains a difficult clinical problem. A recent systematic review of all published case reports of drug-induced thrombocytopenia ranks drugs according to the strength of clinical evidence for a causal relation to thrombocytopenia. This database is available online at http://moon.ouhsc.edu/jgeorge.

Humans↗
PubMed1999

Heparin and low molecular weight heparin for treatment of acute pulmonary embolism.

Pulmonary embolism occurs in more than 175,000 patients each year in the United States. The objectives of treatment are to prevent death from the existing embolus, to prevent death and morbidity from recurrent pulmonary embolism, and to prevent morbidity from recurrent deep-vein thrombosis. For patients with adequate cardiorespiratory reserve, the primary objective is to prevent recurrent pulmonary embolism. Anticoagulant therapy with intravenous unfractionated heparin or subcutaneous low molecular weight heparin followed by oral anticoagulant treatment for at least 3 months is the treatment of choice for most of these patients. Clinical trials indicate that the effectiveness of intravenous heparin depends on achieving an adequate heparin effect (activated partial thromboplastin time above lower limit) during the initial 24 hours. A validated protocol for intravenous heparin should be used to lessen the likelihood of delayed heparinization. Low molecular weight heparin given subcutaneously either once or twice daily is as effective as intravenous heparin for the treatment of patients with deep-vein thrombosis and submassive pulmonary embolism. Low molecular weight heparin enables many patients with uncomplicated deep-vein thrombosis to be treated in an outpatient setting.

Acute Disease↗
PubMed1998

Drug-induced thrombocytopenia: a systematic review of published case reports.

PURPOSE: To determine the strength of clinical evidence for individual drugs as a cause of thrombocytopenia. DATA SOURCES: All English-language reports on drug-induced thrombocytopenia. STUDY SELECTION: Articles describing thrombocytopenia caused by heparin were excluded from review. Of the 581 articles reviewed, 20 were excluded because they contained no patient case reports. The remaining 561 articles reported on 774 patients. DATA EXTRACTION: Two of the authors used a priori criteria to independently review each patient case report. Two hundred fifty-nine patient case reports were excluded from further review because of lack of evaluable data, platelet count of 100000 cells/microL or more, use of cytotoxic or nontherapeutic agents, occurrence of drug-induced systemic disease, or occurrence of disease in children. For the remaining 515 patient case reports, a level of evidence for the drug as the cause of thrombocytopenia was assigned. Data on bleeding complications and clinical course were recorded. DATA SYNTHESIS: The evidence supported a definite or probable causal role for the drug in 247 patient case reports (48%). Among the 98 drugs described in these reports, quinidine was mentioned in 38 case reports, gold in 11, and trimethoprim-sulfamethoxazole in 10. Of the 247 patients described in the case reports, 23 (9%) had major bleeding and 2 (0.8%) died of bleeding. CONCLUSIONS: Many reports of drug-induced thrombocytopenia do not provide evidence supporting a definite or probable causal relation between the disease and the drug. Future patient case reports should incorporate standard criteria to clearly establish the etiologic role of the drug.

Female↗
PubMed1998

Underuse of venous thromboembolism prophylaxis for general surgery patients: physician practices in the community hospital setting.

BACKGROUND: Venous thromboembolism is a common complication of surgery. Although surveys of physician self-reported practices have suggested near universal support for routine use of measures to prevent venous thromboembolism, medical record auditing has demonstrated underuse. OBJECTIVE: To assess physician practices of venous thromboembolism prophylaxis in the community hospital setting. METHODS: Retrospective review of the medical records from 20 hospitals in Oklahoma of 419 Medicare patients aged 65 years or older undergoing major abdominothoracic surgery between April 1 and December 31, 1995. Utilization rates of prophylaxis stratified according to patient risk for venous thromboembolism were measured. RESULTS: Prophylaxis measures were implemented for only 160 (38%) of 419 patients studied (95% confidence interval, 33%-43%). There was little variation in the use of prophylaxis based on the risk for venous thromboembolism. Only 97 (39%) of 250 patients (95% confidence interval, 33%-45%) at very high risk received any form of prophylaxis and of these 97, only 64 patients (66%) received appropriate measures (95% confidence interval, 56%-75%). CONCLUSIONS: Despite widely disseminated, evidence-based recommendations, venous thromboembolism prophylaxis is underused in Medicare patients undergoing major abdominothoracic surgery in community hospitals in Oklahoma.

Abdomen↗
PubMed1998

The clinical validity of normal compression ultrasonography in outpatients suspected of having deep venous thrombosis.

BACKGROUND: Ultrasonography using vein compression accurately detects proximal deep venous thrombosis in symptomatic outpatients. Repeated testing is required for patients with normal results at presentation, but the optimal management of such patients is uncertain. OBJECTIVE: To test the safety of withholding anticoagulation in outpatients suspected of having first-episode deep venous thrombosis who have normal results on simplified compression ultrasonography at presentation and on a single repeated test done 5 to 7 days later. DESIGN: Prospective cohort study. SETTING: Noninvasive vascular laboratories at a university teaching hospital and a Veterans Administration medical center. PATIENTS: 405 consecutive outpatients suspected of having first-episode deep venous thrombosis. INTERVENTION: Ultrasonography was performed at presentation. The common femoral and popliteal veins were assessed for compressibility. If the result was normal, anti-coagulation was withheld and testing was repeated 5 to 7 days later. Anticoagulation was withheld from all patients whose results remained normal according to compression ultrasonography, regardless of their symptoms. The safety of this approach was tested by follow-up lasting 3 months. MEASUREMENTS: Objective testing was done during follow-up in all patients with symptoms or signs of venous thromboembolism. The outcome measure was symptomatic venous thrombosis or pulmonary embolism during follow-up, confirmed by objective testing. RESULTS: Ultrasonography had normal results in 335 patients (83%) and abnormal results in 70 (17%). None of the patients with normal results died of pulmonary embolism. Venous thromboembolism occurred during follow-up in 2 patients with normal ultrasonographic results (0.6% [95% CI, 0.07% to 2.14%]) and in 4 patients with abnormal results (5.7% [CI, 1.58% to 13.99%]) (P = 0.009). CONCLUSIONS: It is safe to withhold anticoagulation in outpatients suspected of having first-episode deep venous thrombosis if results of simplified compression ultrasonography are normal at presentation and on a single repeated test done 5 to 7 days later.

Adolescent↗
PubMed1998

The economic impact of treating deep vein thrombosis with low-molecular-weight heparin: outcome of therapy and health economy aspects.

Subcutaneous low-molecular-weight heparin (LMWH) is at least as safe and effective as classical intravenous heparin therapy for the treatment of proximal vein thrombosis. Anticoagulant monitoring and intravenous administration are not required with LMWH treatment, therefore this therapy may offer economic advantages. An economic evaluation of these therapeutic approaches was performed comparing the costs and effectiveness. The evaluation was aimed at helping decision-makers to maximize the health of the population served, subject to available resources. The American-Canadian Thrombosis Study was a multicentre, randomized, double-blind clinical trial that compared treatment by initial continuous intravenous infusion of heparin (followed by 3 months of warfarin therapy) with a once-daily dose of subcutaneous LMWH, tinzaparin sodium (followed by 3 months of warfarin treatment) in patients with acute proximal deep vein thrombosis. In the LMWH-treated group, the cost incurred for 100 patients was $399,403 (Canadian) or $335,687 (US) with a frequency of objectively documented recurrent venous thromboembolism of 2.8%. In the intravenous heparin-treated group, the cost incurred for 100 patients was $ 414,655 (Canadian) or $ 375,836 (US), with a frequency of objectively documented recurrent venous thromboembolism of 6.9%. These results show a cost saving of $ 15,252 (Canadian) or $ 40,149 (US) with the use of LMWH. Multiple sensitivity analyses did not alter the findings of the study which indicated that LMWH therapy is at least as safe and effective but less costly than intravenous heparin treatment. The potential for outpatient therapy in up to 37% of patients who are receiving LMWH would substantially augment the cost-saving. The cost-effectiveness findings presented in this paper are based on the assumption that all costs are covered by a single payer. Outpatient management in many countries will shift the healthcare costs from the healthcare payer to the patient, increasing the economic burden to the patient.

Anticoagulants↗
PubMed1998

Idiopathic thrombocytopenic purpura: a guideline for diagnosis and management of children and adults. American Society of Hematology.

Idiopathic thrombocytopenic purpura (ITP, also known as immune thrombocytopenic purpura) affects both children and adults. In childhood, the peak age is 2-4 years, girls and boys are equally affected, and in most children, the disease is self-limited with spontaneous recovery occurring in several weeks to several months. In adults, ITP is most common among young women, and the disease is more insidious in its onset and chronic in its course. In both children and adults, there are important unresolved issues in diagnosis and management that have major cost implications. For this reason, the American Society of Hematology chose ITP as the disease topic for its initial practice guideline in 1993. In 1996, the practice guideline was published in Blood, the Journal of the American Society of Hematology. This review describes the principle features of ITP in children and adults, the process of development of the practice guideline for ITP, and the implications of the guideline for the diagnosis and management of patients with ITP.

Adult↗
PubMed1998

Idiopathic thrombocytopenic purpura: A concise summary of the pathophysiology and diagnosis in children and adults.

Idiopathic thrombocytopenic purpura (ITP) is a disorder that has distinct clinical manifestations in children and adults. In children, ITP is typically abrupt in onset and self-limited in its course. Girls and boys are equally affected. In adults, ITP is typically more indolent in its onset and the course is persistent, often lasting many years or characterized by recurrent exacerbations of disease. Most patients are young women. Intracerebral hemorrhage, while rare, is the most common cause of death in children and adults with ITP. In both children and adults, the ITP is assumed to be caused by antibody-mediated platelet consumption, where Fc receptors on the macrophage bind to antibody-coated platelets resulting in an accelerated platelet destruction. However, tests for antiplatelet antibodies have not yet been established as clinically useful for management decisions. The natural history and long-term prognosis of adults with ITP remain incompletely defined.

Adult↗
PubMed1998

Different effects of heparin in males and females.

OBJECTIVE: To determine whether women have a Pharmacological predisposition to bleeding and a worse outcome than men during heparin therapy, in light of recent studies showing that women have a higher risk of bleeding complications following anticoagulant therapy for thrombotic disorders than men. DESIGN: Prospectively planned subgroup analysis of a double-blind randomized study. SETTING: Academic tertiary care hospitals in Hamilton, Ont. PATIENTS: A total of 199 consecutive patients (105 women, 93 men) presenting with proximal deep vein thrombosis. (One patient was not included due to incomplete data). OUTCOME MEASURES: Activated partial thromboplastin time (APTT) values and heparin levels were assessed every 4 to 6 hours after a standard heparin bolus and infusion. The effect of sex on heparin doses and levels was also assessed after stable therapeutic heparin infusions were achieved. RESULTS: The women had higher heparin levels than the men (0.560 [standard error of the mean, SEM 0.056] units/mL v. 0.347 [SEM 0.062] units/mL, p < 0.0001) and higher APTT values (94.9 [SEM 0.50] seconds v. 81.2 [SEM 0.53] seconds, p = 0.0002) 4 to 6 hours after being given the same heparin bolus and infusion doses. After achieving therapeutic APTT values, the women received lower heparin doses than the men (27.9 [SEM 0.24] 1000 units/24 hours v. 34.5 [SEM 0.24] 1000 units/24 hours, p < 0.0001) but had higher heparin levels (0.349 [SEM 0.035] units/mL v. 0.292 [SEM 0.036] units/mL, p = 0.034). The effect of sex was also determined after correcting for the known effects of weight and age on heparin therapy. After adjusting for patient weight, among the women, older women had higher heparin levels but, among the men, there was little effect of age. There were no sex differences with respect to bleeding complications or recurrent thromboembolic disease. CONCLUSION: Women showed alterations in the pharmacokinetics of heparin, which could explain a predisposition to bleeding complications. Under the heparin protocol used in this study, heparin doses were rapidly adjusted, which may explain why rates of bleeding complications and recurrent thromboembolism were similar in men and women. We do not recommend changes in heparin therapy based on these results, but suggest the use of protocols that assess coagulation parameters frequently and then adjust heparin doses rapidly, in order to individualize therapy. Further study is required to determine whether there are sex differences in bleeding complications associated with anticoagulant therapy, and to confirm the altered pharmacokinetics of heparin in women.

Aging↗