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Biomedical subjects

G E Raskob

Publications and source records attributed to G E Raskob.

At least 55 records · Page 3Linked to original sources
PubMed1995

Low molecular weight heparin, heparin, and warfarin.

Low molecular weight heparin is effective for the prevention and treatment of venous thromboembolism. Low molecular weight heparin has the practical advantage that it does not require anticoagulant monitoring and dose adjustment. The simplified therapy provided by low molecular weight heparin may allow many patients with venous thromboembolism to be cared for in an outpatient setting, with the potential for major savings in health care costs. In the setting of preventing venous thromboembolism after hip or knee replacement surgery, further cost-effectiveness studies are required to determine the ultimate clinical role of low molecular weight heparin. Extensive data document a consistent high rate of inadequate therapy when empirical or intuitive approaches are used to administer intravenous unfractionated heparin in patients with venous thromboembolism or cardiovascular disease. A validated protocol should be used for intravenous heparin treatment. The evidence is accumulating that warfarin is more effective than aspirin for preventing thromboembolism in patients with atrial fibrillation.

Anticoagulants↗
PubMed1995

Cost effectiveness of diagnosis of deep vein thrombosis in symptomatic patients.

BACKGROUND: The most widely used noninvasive test for deep vein thrombosis is Doppler ultrasonographic imaging of the lower extremities. The best evaluated of the noninvasive approaches are ascending contrast venography, impedance plethysmography, Doppler ultrasonography with B-mode imaging. Economic evaluation is aimed at helping decision makers to reach their goal of maximizing the health of the population served, subject to the available resources. METHODS: The data that provided the basis for this cost effectiveness analysis were derived from a prospective study of approximately 500 patients referred to a regional thromboembolism program with a first episode of clinically suspected deep vein thrombosis. The application of cost effectiveness analysis to the diagnosis of deep vein thrombosis is readily accomplished using cost minimization. This cost effectiveness technique makes it possible to rank the diagnostic approaches from "worst" to "best", with the best approach defined as that which accomplishes the desired health effect at minimum cost. Effectiveness (health benefit) may be defined in this context as the number or proportion of patients with deep vein thrombosis correctly identified by objective testing or, the number or proportion in whom treatment was correctly withheld. RESULTS: Clinical diagnosis is cost ineffective; $1,590,784 Canadian, $2,624,220 US. Outpatient diagnosis using noninvasive testing was the most cost effective. Serial Doppler ultrasonography is more costly ($618,265 Canadian, $1,326,180 US) than serial impedance plethysmography ($527,165 Canadian, $1,052,880 US). Combined Doppler ultrasonography and serial impedance plethysmography offers a less costly strategy ($551,065 Canadian, $1,124,580 US) than serial ultrasonography alone. DISCUSSION: Objective testing is mandatory. Outpatient testing is preferred, avoiding unnecessary hospital admissions. Noninvasive testing is the most cost effective. The most widely used test, serial Doppler ultrasonography, is less cost effective than serial impedance plethysmography. The combined approach of initial Doppler ultrasonography followed by serial impedance plethysmography combines the advantage of an initial ultrasound image with less costly serial impedance plethysmography.

Adolescent↗
PubMed1995

Anticoagulants and thrombolysis in the treatment of pulmonary embolism.

Intravenous heparin followed by oral warfarin sodium is effective for preventing recurrent thromboembolism in patients who have pulmonary embolism or proximal vein thrombosis. The effectiveness of intravenous heparin depends on obtaining an adequate anticoagulant response early during therapy. A validated heparin protocol should be used to ensure that an adequate anticoagulant response is obtained as soon as possible. Low molecular weight heparin has the practical advantage that it does not require monitoring and dose finding. If thrombolytic therapy is indicated, it is safer for many patients to base management on the noninvasive diagnosis rather than performing pulmonary angiography. In patients suspected to have pulmonary embolism who have nondiagnostic lung scan and adequate cardiorespiratory reserve, serial noninvasive leg testing is a practical approach that avoids pulmonary angiography, identifies patients who have proximal vein thrombosis requiring treatment, and avoids the risks of anticoagulant treatment in the majority of patients.

Anticoagulants↗
PubMed1994

Safety and anticoagulation effect of a low-dose combination of warfarin and aspirin in clinically stable coronary artery disease. Coumadin Aspirin Reinfarction (CARS) Pilot Study Group.

The hypothesis that the combination of low-dose aspirin and warfarin therapy is more effective than aspirin alone in secondary prophylaxis after myocardial infarction is to be examined in the Coumadin Aspirin Reinfarction Study. This pilot study addressed the safety and anticoagulation effect of a fixed, low-dose combination in 114 patients (aged 64 +/- 8 years, 85% men) with stable coronary artery disease receiving 3 mg of warfarin plus 80 mg of aspirin daily for 8 weeks. The international normalized ratio (INR) was measured within 72 hours of initial therapy, and weekly. Of the 110 patients with evaluable INRs, 87 patients (79%) maintained the 3 + 80 mg combination, 19 (17%) had the dose reduced to 1 mg warfarin + 80 mg aspirin, and 4 (4%) discontinued therapy because of a confirmed INR of > or = 4.5. At steady state, patients had INRs of 1.48 +/- 0.41 (3 + 80 mg group) and 1.21 +/- 0.23 (1 + 80 mg group), and inter- and intra-patient variability (estimated by the mean of the between- and within-patient SDs at steady state) was 0.49 +/- 0.08 and 0.13 +/- 0.14, respectively. There was no apparent effect of age on INR distribution. Microscopic hematuria was the most frequent (20%) adverse clinical event, but was unrelated to the INR. Three patients required discontinuation of therapy because of bleeding events (persistent hematuria and epistaxis). A fixed low-dose combination of warfarin and aspirin results in a predictable and stable increase in the INR in a large proportion of patients with coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Physician-guided treatment compared with a heparin protocol for deep vein thrombosis.

BACKGROUND: Effective heparin therapy, defined by therapeutic prolongation of the activated partial thromboplastin time (APTT), decreases the risk of recurrent venous thromboembolism. Achieving therapeutic prolongation of the APTT within 24 hours of the start of heparin therapy has proved difficult. We hypothesized that a protocol that delivered high initial heparin infusions to patients without identifiable risk for bleeding complications would decrease the time to achieve a therapeutic anticoagulant effect without increasing the incidence of major bleeding complications. METHODS: To test this hypothesis, we studied concurrent patient cohorts. We defined a therapeutic anticoagulant effect (APTT > 55 seconds) to be an APTT more than 1.5 times the upper limit of normal. Twenty patients with acute symptomatic deep vein thrombosis received a 5000-U heparin bolus, followed by 1680 U/h (low risk to bleed) or 1240 U/h (high risk to bleed), adjusted by protocol-directed response to APTT results. Forty-eight patients with deep vein thrombosis were treated by their physicians. The Kaplan-Meier method was used to examine the proportion of patients who achieved an APTT greater than 55 seconds as a function of time. RESULTS: The two study cohorts did not differ with respect to age, weight, or risk factors for venous thromboembolism. Analysis of Kaplan-Meier curves showed that the heparin protocol decreased the time to achieve a therapeutic anticoagulant effect (P = .025). Ten (91%) of 11 patients (95% confidence interval, 59% to 100%) without risks to bleed who were treated by the heparin protocol and 29 (60%) of 48 patients (95% confidence interval, 45% to 74%) not treated by the protocol had an initial therapeutic APTT (P = .006). CONCLUSION: A protocol that delivers higher initial heparin infusions to patients without identifiable risks for bleeding decreases the time needed to achieve therapeutic prolongation of APTT, when compared with nonprotocol physician management.

Aged↗
PubMed1994

A noninvasive strategy for the treatment of patients with suspected pulmonary embolism.

BACKGROUND: Pulmonary embolism has historically presented a formidable diagnostic problem because of the nonspecificity of the clinical findings associated with this disorder and the diagnostic uncertainties and challenges presented by both ventilation-perfusion lung scanning and pulmonary angiography. We have reported previously that serial noninvasive leg testing provides a practical noninvasive alternative to pulmonary angiography in patients with non-high probability (nondiagnostic) lung scans and adequate cardiorespiratory reserve. We have reevaluated this observation prospectively to (1) confirm or refute our original observation in an independent cohort and (2) to increase the numbers sufficiently to provide narrow confidence limits for the observed outcomes. METHODS: A prospective comparative study in 1564 consecutive patients with suspected pulmonary embolism who underwent ventilation-perfusion lung scanning and objective testing for proximal-vein thrombosis. RESULTS: On long-term follow-up of 627 patients with the following characteristics: (1) abnormal, nondiagnostic lung scans, (2) not taking anticoagulant therapy, and (3) serial noninvasive test results negative for proximal-vein thrombosis, only 12 patients (1.9%; 95% confidence limits, 0.8% to 3.0%) had venous thromboembolism. By comparison, venous thromboembolism on follow-up occurred in four (0.7%) of 586 patients (95% confidence limits, 0.02% to 1.3%) with normal lung scans in whom anticoagulant therapy was withheld and in eight (5.5%) of 145 patients (95% confidence limits, 1.8% to 9.2%) with high probability lung scans who received anticoagulant therapy. CONCLUSIONS: Our findings indicate that the clinician has a practical noninvasive strategy in patients with adequate cardiorespiratory reserve and nondiagnostic lung scans that (1) avoids pulmonary angiography, (2) identifies patients with proximal-vein thrombosis who require treatment, and (3) avoids the need for treatment and further investigation in the majority of patients.

Adolescent↗
PubMed1994

Preventing systemic embolism in patients with abnormal ventricular function.

Clinical trial results support the aggressive use of anticoagulant therapy to prevent systemic embolism in patients with acute myocardial infarction who are at high risk for embolism (e.g., anterior transmural infarction). Other patients at risk for systemic embolism include those with chronic left ventricular aneurysm, chronic dilated cardiomyopathy, and cardiac tumors. The role of antithrombotic therapy in these latter groups is incompletely resolved because of a lack of clinical trials. However, in view of the devastating consequences of systemic embolism, the documented effectiveness of antithrombotic therapy in other high-risk patients and the improved safety of long-term anticoagulant treatment in recent years, it may be prudent to use antithrombotic treatment unless contraindicated.

Anticoagulants↗
PubMed1994

Treatment of venous thromboembolism.

There have been some important advances in the treatment of venous thromboembolism during the past 18 months. A randomized trial has confirmed earlier observations indicating an adequate initial heparin effect is required to prevent recurrent venous thromboembolism, and it is critical to achieve this effect within the first 24 hours of therapy. The need to use a validated protocol for administering intravenous heparin is now firmly established. The clinician has a choice between two protocols that have been validated by randomized trials and provide both effective and safe heparin therapy. For patients with clinically suspected pulmonary embolism, the clinician now has a practical noninvasive strategy that avoids pulmonary angiography, identifies patients with proximal-vein thrombosis who require treatment, and avoids the need for treatment and further investigation in the majority of patients.

Heparin↗
PubMed1993

Long-term oral anticoagulant therapy for coronary artery disease.

The findings of recent clinical trials have led to renewed interest in the role of oral anticoagulant therapy in patients with coronary artery disease. However, there are currently two major limitations to the routine use of oral anticoagulant therapy. The first is the need for laboratory monitoring and dose adjustment. This limitation may be overcome if fixed low doses of warfarin (e.g. 1 mg/day), which have antithrombotic effects, are shown by clinical trials to be effective and safe. A second limitation to oral anticoagulant therapy is uncertainty about its effectiveness and safety compared to aspirin, or in combination with aspirin. The current pathophysiologic knowledge and recent clinical trial data provide support for further clinical trials evaluating combined warfarin and aspirin treatment in the long-term care of patients with coronary artery disease, and in the primary prevention of myocardial infarction.

Administration, Oral↗
PubMed1992

Subcutaneous low-molecular-weight heparin compared with continuous intravenous heparin in the treatment of proximal-vein thrombosis.

BACKGROUND: Low-molecular-weight heparin has a high bioavailability and a prolonged half-life in comparison with conventional unfractionated heparin. Limited data are available for low-molecular-weight heparin as compared with unfractionated heparin for the treatment of deep-vein thrombosis. METHODS: In a multicenter, double-blind clinical trial, we compared fixed-dose subcutaneous low-molecular-weight heparin given once daily with adjusted-dose intravenous heparin given by continuous infusion for the initial treatment of patients with proximal-vein thrombosis, using objective documentation of clinical outcomes. RESULTS: Six of 213 patients who received low-molecular-weight heparin (2.8 percent) and 15 of 219 patients who received intravenous heparin (6.9 percent) had new episodes of venous thromboembolism (P = 0.07; 95 percent confidence interval for the difference, 0.02 percent to 8.1 percent). Major bleeding associated with initial therapy occurred in 1 patient receiving low-molecular-weight heparin (0.5 percent) and in 11 patients receiving intravenous heparin (5.0 percent), a reduction in risk of 91 percent (P = 0.006). This apparent protection against major bleeding was lost during long-term therapy. Minor hemorrhagic complications were infrequent. Ten patients receiving low-molecular-weight heparin (4.7 percent) died, as compared with 21 patients receiving intravenous heparin (9.6 percent), a risk reduction of 51 percent (P = 0.049). CONCLUSIONS: Low-molecular-weight heparin is at least as effective and as safe as classic intravenous heparin therapy under the conditions of this study and more convenient to administer. The simplified therapy provided by low-molecular-weight heparin may allow patients with uncomplicated proximal deep-vein thrombosis to be cared for in an outpatient setting.

Double-Blind Method↗
PubMed1992

Optimal therapeutic level of heparin therapy in patients with venous thrombosis.

BACKGROUND: Audits of heparin sodium therapy suggest that heparin administration is fraught with difficulty. The literature indicates that the current clinical practice of intuitive ordering of heparin results in inadequate therapy because of fear of bleeding. The importance of exceeding the lower limit of the therapeutic range has been strongly supported by findings of prospective clinical trials. Firm evidence indicates that failure to exceed the lower limit is associated with unacceptably high rates of recurrent venous thromboembolism. By comparison, evidence supporting the risk of exceeding the upper limit of the therapeutic range is weak. OBJECTIVES: The purposes of this study were (1) to validate prospectively an approach designed to minimize the proportion of patients receiving subtherapeutic doses of heparin and (2) to determine the effectiveness and safety of decreasing the heparin dosage infused on the basis of activated partial thromboplastin time (APTT) prolongation reflecting both heparin and warfarin sodium effects. METHODS: We performed a randomized double-blind study evaluating a prescriptive approach to heparin administration in patients receiving heparin or heparin with warfarin. Thromboembolic and bleeding complications were objectively documented. RESULTS: Only 1% and 2% of patients had subtherapeutic heparin levels for 24 hours or more in the heparin and combined groups, respectively. Recurrent venous thromboembolism occurred infrequently in both groups (7%). Sixty-nine (69%) of 99 patients receiving combined therapy had supratherapeutic values, compared with 24 (24%) of 100 receiving heparin; bleeding complications occurred in 9% and 12%, respectively. CONCLUSIONS: Our findings demonstrate that no association exists between supratherapeutic APTT responses and bleeding, which is in direct contrast to the observed association between subtherapeutic APTT responses and recurrent venous thromboembolism.

Double-Blind Method↗
PubMed1991

Venous thromboembolic disease.

During the past year, the findings of several clinical trials have been published that have important implications for the care of patients with venous thromboembolism. These clinical trials have produced advances in the diagnosis and treatment of venous thrombosis and pulmonary embolism and in the prevention of venous thromboembolism in high-risk patients. In patients with clinically suspected pulmonary embolism, the value and limitations of ventilation-perfusion lung scanning have been established, and it is now accepted that objective tests for deep vein thrombosis have an important role. There have been important advances also in the diagnosis of deep vein thrombosis; these advances include the finding that impedance plethysmography is effective in pregnant symptomatic patients and the development of an objective technique for Doppler ultrasound. The optimal duration of initial intravenous heparin treatment of established thrombosis has been determined. In the prevention of venous thromboembolism, the effectiveness of sequential intermittent compression in patients having hip replacement has been established, and further data on the effectiveness of low-molecular-weight heparin in high-risk patients have become available.

Heparin↗
PubMed1990

Heparin for 5 days as compared with 10 days in the initial treatment of proximal venous thrombosis.

It is common practice to begin anticoagulant treatment of deep-vein thrombosis with a 10-day course of intravenous heparin, with warfarin added on day 5 to 10 and continued for several months. We performed a randomized, double-blind trial comparing a shorter course of continuous intravenous heparin (5 days, with warfarin sodium begun on the first day) with the conventional 10-day course of heparin (with warfarin sodium begun on the fifth day) in the initial treatment of 199 patients with acute proximal venous thrombosis documented by venography. The frequency of objectively documented recurrent venous thromboembolism was low and essentially the same in the two groups (7.1 percent in the short-course group vs. 7.0 percent in the long-course group). Because the observed difference between the groups was 0.1 percent in favor of the long-course group, it is unlikely (P less than 0.05) that a true difference in favor of this group would be greater than 7.5 percent; the difference could be as much as 7.3 percent in favor of the short-course group. Major bleeding episodes were infrequent, and the rate was similar in both groups. We conclude that a five-day course of heparin is as effective as a 10-day course in treating deep venous thrombosis. Furthermore, using the shorter course would permit earlier discharge from the hospital and thus offer substantial cost savings.

Acute Disease↗
PubMed1990

Effectiveness of intermittent pneumatic leg compression for preventing deep vein thrombosis after total hip replacement.

A randomized trial was performed in consecutive patients undergoing total hip replacement to evaluate the effectiveness of sequential intermittent calf and thigh compression for preventing venous thrombosis compared with a control group given no prophylaxis. Both groups underwent case finding for deep vein thrombosis using combined fibrinogen I 125 leg scanning, impedance plethysmography, and venography. Deep vein thrombosis by venography was present in 77 (49%) of 158 control patients compared with 36 (24%) of 152 patients given intermittent compression. Proximal vein thrombosis was present in 42 controls (27%) compared with 22 patients (14%) given intermittent compression. Combined impedance plethysmography and leg scanning was insensitive in this patient group (sensitivity, 46%); venography was required to detect more than half the patients with venous thrombosis. Sequential intermittent leg compression clinically and statistically significantly reduced the frequency of both proximal vein and calf vein thrombosis. Case finding resulted in early detection and treatment of patients with venous thrombosis.

Female↗
PubMed1990

Serial impedance plethysmography in pregnant patients with clinically suspected deep-vein thrombosis. Clinical validity of negative findings.

STUDY OBJECTIVE: To determine the safety of withholding anticoagulant therapy in pregnant patients with clinically suspected deep-vein thrombosis who have negative results by serial impedance plethysmography. DESIGN: Prospective study evaluating prognosis by long-term follow-up to 3 months postpartum in all patients. SETTING: University-affiliated community hospital and referral center. PATIENTS: One hundred fifty-two consecutive pregnant patients referred with clinically suspected deep-vein thrombosis. All patients completed the study. INTERVENTIONS: Anticoagulant therapy was withheld in 139 patients negative by serial impedance plethysmography, and the patients were followed long term. MEASUREMENTS AND MAIN RESULTS: None of 139 patients (0%; 95% CI, 0% to 2.6%) had symptomatic pulmonary embolism or recurrent venous thrombosis. CONCLUSIONS: The findings establish the safety of withholding anticoagulant therapy in pregnant patients who have negative results after serial impedance plethysmography. Sufficient patients were entered to provide narrow confidence intervals on the outcomes observed in patients with negative findings by impedance plethysmography. These findings are similar to those seen after venography in symptomatic patients. These data extend the role of non-invasive testing in patients with clinically suspected deep-vein thrombosis to the pregnant symptomatic patient.

Adolescent↗