Hemorrhagic complications of long-term anticoagulant therapy

Rectal colonic mural hematoma following enema for constipation while on therapeutic anticoagulation

Causes of colonic and recto-sigmoid hematomas are multifactorial. Patients can present with a combination of dropping hemoglobin, bowel obstruction and perforation. Computed tomography imaging can provide clues to a diagnosis of intramural hematoma. We present a case of rectal hematoma and a review of current management literature. A 72-year-old male on therapeutic anticoagulation for a pulmonary embolism, was administered an enema resulting in severe abdominal pain unresponsive to blood transfusion. A sigmoid colectomy with end colostomy was performed. Although rare, colonic and recto-sigmoid hematomas should be considered as a possible diagnosis for adults with abdominal pain on anticoagulant therapy.

Familial Thrombophilia: A Review Analysis

The correct approach to the management of the asymptomatic carrier with a recognized inherited thrombophilic disorder is uncertain because reliable in formation of the risk of spontaneous (unprovoked) throm bosis in these disorders is not available. To determine the best available estimate of the annual incidence of spon taneous thrombosis in asymptomatic carriers of disorders that have been linked to familial thrombophilia, we per formed a literature review. Using Medline search from 1965 to 1992, supplemented by manual searches, we re trieved all articles that presented data on antithrombin III, protein C, protein S, dysfibrinogenemia, plasmino gen, histidine-rich glycoprotein, heparin cofactor II, and fibrinolysis in relation to thrombosis. Publications were included in the analysis if they (1) reported one or more probands with thrombotic disease and a heterozygous biochemical abnormality of the hemostatic system, (2) assessed the presence of this abnormality in family mem bers independent of the presence or absence of a history of thrombotic disease, and (3) assessed the presence of a history of thrombotic disease in all available family mem bers. The biochemical status and clinical details of all family members reported were extracted from each eligi ble article. For each abnormality the odds ratio for throm bosis was compared in family members with and without the biochemical abnormality. If applicable, thrombosis- free survival and age-specific incidences of thrombosis were calculated. The thrombotic episodes were classified as spontaneous or secondary to a recognized risk factor, and the proportion of spontaneous episodes was calcu lated. The influence of diagnostic suspicion bias in symp tomatic patients with a family history of thrombosis was reduced by recalculating the absolute incidence of throm bosis from the odds ratio after adjusting the incidence of venous thrombosis in nonaffected family members to that observed in the general population. Statistically signifi cant associations between the presence of a biochemical abnormality and a history of venous thrombosis were found for antithrombin III deficiency types 1 and 2a and 2b, protein C deficiency type 1, and protein S deficiency type I. Dysfibronogenemia was statistically significantly associated with venous as well as arterial thrombosis. Thirty-five to 67% of the events were classified as being provoked, as they occurred following exposure to a rec ognized risk factor for thrombosis. The recalculated an nual incidence of spontaneous thrombosis was 0.6 to 1.6%/year. It is concluded that this relatively low inci dence does not warrant life-long continuous use of anti coagulant prophylaxis since the reported risk of major and fatal bleeding associated with the use of oral antico agulants is 2-3 and 0.4%/year, respectively.

Quadruple Valve Replacement with Mechanical Valves: An 11-Year Follow-up Study

<p><b>Background:</b> We performed the first quadruple valve replacement with mechanical valves, combined with the correction of complex congenital heart disease on November 17, 1999. We report here the 11-year follow-up study.</p><p><b>Methods:</b> A 47-year-old man with subacute rheumatic endocarditis, a ventricular septal defect, and an obstruction of the right ventricular outflow tract required replacement of the aortic, mitral, tricuspid, and pulmonary valves; repair of the ventricular septal defect; and relief of the obstruction of the right ventricular outflow tract. The surgery was done on November 17, 1999, after careful systemic preparation of the patient. Warfarin therapy with a target international normalized ratio (INR) range of 1.5 to 2.0 was used. Follow-up included monitoring the INR, recording the incidences of thromboembolic and bleeding events, electrocardiography, radiography, and echocardiography evaluations.</p><p><b>Results:</b> The patient's INR was maintained between 1.5 and 2.0. All 4 mechanical prosthetic heart valves worked well. He is in generally good health without any thromboembolic or bleeding complications.</p><p><b>Conclusions:</b> Long-term management is challenging for patients who have experienced quadruple valve replacement with mechanical valves; however, promising results could mean that replacement of all 4 heart valves in 1 operation is feasible in patients with quadruple valve disease, and an INR of 1.5 to 2.0 could be appropriate for Chinese patients with undergoing valve replacement with mechanical valves.</p>

Warfarin administration disrupts the assembly of mineralized nodules in the osteoid

This study aimed to elucidate the ultrastructural role of Gla proteins in bone mineralization by means of a warfarin-administration model. Thirty-six 4-week-old male F344 rats received warfarin (warfarin group) or distilled water (control group), and were fixed after 4, 8 and 12 weeks with an aldehyde solution. Tibiae and femora were employed for histochemical analyses of alkaline phosphatase, osteocalcin and tartrate-resistant acid phosphatase, and for bone histomorphometry and electron microscopy. After 4, 8 and 12 weeks, there were no marked histochemical and histomorphometrical differences between control and warfarin groups. However, osteocalcin immunoreactivity was markedly reduced in the warfarin-administered bone. Mineralized nodules and globular assembly of crystalline particles were seen in the control osteoid. Alternatively, warfarin administration resulted in crystalline particles being dispersed throughout the osteoid without forming mineralized nodules. Immunoelectron microscopy unveiled lower osteocalcin content in the warfarin-administered osteoid, which featured scattered crystalline particles, whereas osteocalcin was abundant on the normally mineralized nodules in the control osteoid. In summary, Gla proteins appear to play a pivotal role in the assembly of mineralized nodules.

Bleeding complications in patients on celecoxib and warfarin1

PURPOSE

Non-selective non-steroidal anti-inflammatory drugs (nNSAIDs) used in combination with warfarin are associated with an approximately 3-fold increased risk of upper gastrointestinal bleeding (UGIB) compared with warfarin alone. Celecoxib, a selective inhibitor of cyclo-oxygenase 2 (COX-2), is associated with less gastric mucosal injury and platelet dysregulation than nNSAIDs. We compared rates of bleeding complications in patients taking celecoxib and warfarin with those taking warfarin alone.

SUBJECTS AND METHODS

We performed a retrospective analysis using data from our Protime Clinic and pharmacy databases from January 2001 to April 2004. We identified 123 patients who took celecoxib and warfarin concurrently (overlap group). We compared rates of bleeding complications in this group with 1022 control patients who were taking warfarin alone. Bleeding complications were defined as major if they resulted in hospitalization, blood transfusion or death.

RESULTS

During approximately 1063 months of exposure to both celecoxib and warfarin, 10 bleeding complications were identified, only one of which was considered major. No patients had UGIB. In the control group, 116 bleeding complications were identified over approximately 16 520 months of exposure to warfarin alone, with 101 minor and 15 major events, including six episodes of UGIB. The relative risk of all bleeding complications was 1.34 (95% CI: 0.70-2.57) in the overlap vs. control groups, and for major bleeds was 1.04 (95% CI: 0.14-7.85).

CONCLUSIONS

There is a mild but non-significant increase in bleeding complications in patients taking celecoxib and warfarin compared with those taking warfarin alone.

Surgical Closure of Combined Symptomatic Patent Foramen Ovale and Atrial Septum Aneurysm for Prevention of Recurrent Cerebral Emboli

BACKGROUND

Patients with patent foramen ovale (PFO) have an undefined but certainly considerable risk of repeated cerebral ischemia due to paradoxical embolism. Especially, if a cerebrovascular event has already occurred and the combination with an atrial septum aneurysm (ASA) is present this risk increases tremendously. The aim of this study was to demonstrate that surgical closure of PFO in combination with an ASA is safe and useful in preventing recurrent strokes.

METHODS

Ten patients with previous cerebral ischemia, proven by CT or MRI, and PFO in combination with an ASA were prospectively scheduled for surgical closure. Patients with extracardiac sources of embolic disease were excluded from this study. However, one patient suffered from a hypercoagulability syndrome.

RESULTS

All patients (mean age 35.5 +/- 19.1 years) underwent direct suture of the PFO and plication of the ASA with the aid of cardiopulmonary bypass and cardioplegic arrest (n = 3) or ventricular fibrillation (n = 7). Mean operation time was 123.1 +/- 20.2 minutes; mean bypass time was 34.5 +/- 9.9 minutes. There was no mortality or significant postoperative morbidity. Mean hospital stay was 5.1 +/- 1.5 days. During a follow-up of >4 years, no recurrent stroke or transient ischemic attack occurred and no patient received anticoagulation therapy.

CONCLUSION

Our data suggest that surgical closure of PFO in combination with ASA in patients with previous stroke is safe and efficacious to prevent recurrent strokes and avoids lifelong anticoagulation.

Hemorrhagic Complications of Anticoagulant Treatment

This chapter about hemorrhagic complications of anticoagulant treatment is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Bleeding is the major complication of anticoagulant therapy. The criteria for defining the severity of bleeding varies considerably between studies, accounting in part for the variation in the rates of bleeding reported. The major determinants of vitamin K antagonist-induced bleeding are the intensity of the anticoagulant effect, underlying patient characteristics, and the length of therapy. There is good evidence that vitamin K antagonist therapy, targeted international normalized ratio (INR) of 2.5 (range, 2.0 to 3.0), is associated with a lower risk of bleeding than therapy targeted at an INR > 3.0. The risk of bleeding associated with IV unfractionated heparin (UFH) in patients with acute venous thromboembolism (VTE) is < 3% in recent trials. This bleeding risk may increase with increasing heparin dosages and age (> 70 years). Low molecular weight heparin (LMWH) is associated with less major bleeding compared with UFH in acute VTE. UFH and LMWH are not associated with an increase in major bleeding in ischemic coronary syndromes, but are associated with an increase in major bleeding in ischemic stroke. Information on bleeding associated with the newer generation of antithrombotic agents has begun to emerge. In terms of treatment decision making for anticoagulant therapy, bleeding risk cannot be considered alone, ie, the potential decrease in thromboembolism must be balanced against the potential increased bleeding risk.

Long-term treatment with sodium warfarin results in decreased femoral bone strength and cancellous bone volume in rats

The issue of whether long-term sodium warfarin therapy results in decreased bone density is controversial. To address this question, we randomized rats to once daily subcutaneous injections of either sodium warfarin (0.20 or 0.25 mg/kg) or saline for 28 days and monitored the effects on bone, both biomechanically and by histomorphometric analysis. In addition, the anticoagulant status of both saline- and warfarin-treated rats were monitored throughout the course of the experiment by measuring the prothrombin time, expressed as international normalized ratios (INRs). Rats treated with 0.25 mg/kg warfarin demonstrated INRs of approximately 2.6, while rats treated with either 0.20 mg/kg warfarin or saline were found to have INRs of 1.3 and 1.0, respectively. Biomechanical testing of the right femur of rats treated with 0.25 mg/kg warfarin demonstrated that warfarin caused an 8% reduction in bone strength as measured by maximum tolerated load. A similar reduction in the biomechanical parameters of energy to break (P<.0001) and force at break point (P<.005) was also observed. Histomorphometric analysis of the left femur of warfarin-treated rats revealed a 17% reduction in cancellous bone volume. This was accompanied by a 60% decrease in osteoblast surface, as well as an 80% reduction in osteoid surface. In contrast, warfarin treatment had the opposite effect on osteoclast surface, which was 35% higher following warfarin treatment. Based on these observations, we conclude that clinically relevant doses of warfarin decrease femoral bone strength and cancellous bone volume, both by decreasing the rate of bone formation and increasing the rate of bone resorption.

Role of transesophageal echocardiography-guided cardioversion of patients with atrial fibrillation

Electrical cardioversion of patients with atrial fibrillation (AF) is frequently performed to relieve symptoms and improve cardiac performance. Patients undergoing cardioversion are treated conventionally with therapeutic anticoagulation for three weeks before and four weeks after cardioversion to decrease the risk of thromboembolism. A transesophageal echocardiography (TEE)-guided strategy has been proposed as an alternative that may lower stroke and bleeding events. Patients without atrial cavity thrombus or atrial appendage thrombus by TEE are cardioverted on achievement of therapeutic anticoagulation, whereas cardioversion is delayed in higher risk patients with thrombus. The aim of this review is to discuss the issues and controversies associated with the management of patients with AF undergoing cardioversion. We provide an overview of the TEE-guided and conventional anticoagulation strategies in light of the recently completed Assessment of Cardioversion Using Transesophageal Echocardiography (ACUTE) clinical trial. The two management strategies comparably lower the patient's embolic risk when the guidelines are properly followed. The TEE-guided strategy with shorter term anticoagulation may lower the incidence of bleeding complications and safely expedite early cardioversion. The inherent advantages and disadvantages of both strategies are presented. The TEE-guided approach with short-term anticoagulation is considered to be a safe and clinically effective alternative to the conventional approach, and it is advocated in patients in whom earlier cardioversion would be clinically beneficial.

Hemorrhagic complications of anticoagulant treatment

Bleeding is the major complication of anticoagulant therapy. The criteria for defining the severity of bleeding varied considerably between studies, accounting in part for the variation in the rates of bleeding reported. Since the last review, there have been several meta-analyses published on the rates of major bleeding in trials of anticoagulants for atrial fibrillation and ischemic heart disease. The major determinants of oral anticoagulant-induced bleeding are the intensity of the anticoagulant effect, underlying patient characteristics, and the length of therapy. There is good evidence that low-intensity oral anticoagulant therapy (targeted INR of 2.5; range, 2.0 to 3.0) is associated with a lower risk of bleeding than therapy targeted at a higher intensity. Lower-intensity regimens (INR < 2.0) are associated with an even smaller increase in major bleeding. In terms of treatment decision making for anticoagulant therapy, bleeding risk cannot be considered alone, ie, the potential decrease in thromboembolism must be balanced against the potential increased bleeding risk. The risk of bleeding associated with IV heparin in patients with acute venous thromboembolism is < 3% in recent trials. There is some evidence to suggest that this bleeding risk increases with the heparin dosage and age (> 70 years). LMW heparin is not associated with increased major bleeding compared with standard heparin in acute venous thromboembolism. Standard heparin and LMW heparin are not associated with an increase in major bleeding in ischemic coronary syndromes, but are associated with an increase in major bleeding in ischemic stroke.

A closed-chest pulmonary artery occlusion/reperfusion model in the pig: detection of experimental pulmonary embolism with MR angiography and perfusion MR imaging

RATIONALE AND OBJECTIVES

To establish a pig model suitable for imitating pulmonary emboli to facilitate research in the diagnosis of pulmonary embolism.

METHODS

Thirteen animals were anesthetized, mechanically ventilated, and subjected to pulmonary artery catheterization initiated from the right external jugular vein. With the use of a Swan-Ganz catheter, repetitive occlusion/reperfusion maneuvers were done at different locations of the pulmonary arterial tree. Conventional pulmonary angiography, MR angiography, and perfusion MR imaging were performed.

RESULTS

The model remained hemodynamically stable throughout the 13 experiments, without any significant difference between the blood pressure measurements at the start and at the end of the right-heart and pulmonary artery catheterizations. In each of the nine animal experiments that investigated MR imaging, four of four using perfusion MR imaging (proximal and distal occlusions) and five of five using MR angiography (larger pulmonary artery occlusions), all repeated pulmonary artery occlusions were successfully performed (reproducibility of 100%).

CONCLUSIONS

The closed-chest pulmonary artery occlusion/reperfusion model in the pig allowed repetitive, controlled imitations of pulmonary emboli at different levels of the pulmonary artery in the same experiment. MR angiography and perfusion MR imaging were adequate to detect the pulmonary artery occlusions and the nonperfused lung regions, respectively. The model may be a helpful tool for future research in this field.

Suspected acute pulmonary emboli: cost-effectiveness of chest helical computed tomography versus a standard diagnostic algorithm incorporating ventilation-perfusion scintigraphy

BACKGROUND

There is a controversy regarding the investigation of patients with suspected acute pulmonary embolism (PE).

AIMS

To compare the cost-effectiveness of alternative methods of diagnosing acute PE. Chest helical computed tomography (CT) alone and in combination with venous ultrasound (US) of legs and pulmonary angiography (PA) were compared to a conventional algorithm using ventilation-perfusion (V/Q) scintigraphy supplemented in selected cases by US and PA.

METHODS

A decision-analytical model was constructed to model the costs and effects of the three diagnostic strategies in a hypothetical cohort of 1000 patients each. Transition probabilities were based on published data. Life years gained by each strategy were estimated from published mortality rates. Schedule fees were used to estimate costs.

RESULTS

The V/Q protocol is both more expensive and more effective than CT alone resulting in 20.1 additional lives saved at a (discounted) cost of $940 per life year gained. An additional 2.5 lives can be saved if CT replaces V/Q scintigraphy in the diagnostic algorithm but at a cost of $23,905 per life year saved.

CONCLUSIONS

The more effective diagnostic strategies are also more expensive. In patients with suspected PE, the incremental cost-effectiveness of the V/Q based strategy over CT alone is reasonable in comparison with other health interventions. The cost-effectiveness of the supplemented CT strategy is more questionable.

Clinical utilization of the international normalized ratio (INR)

The prothrombin time (PT) is one of the most important laboratory tests to determine the functionality of the blood coagulation system. It is used in patient care to diagnose diseases of coagulation, assess the risk of bleeding in patients undergoing operative procedures, monitor patients being treated with oral anticoagulant (coumadin) therapy, and evaluate liver function. The PT is performed by measuring the clotting time of platelet-poor plasma after the addition of calcium and thromboplastin, a combination of tissue factor and phospholipid. Intra- and interlaboratory variation in the PT was a significant problem for clinical laboratories in the past, when crude extracts of rabbit brain or human placenta were the only source of thromboplastin. The international normalized ratio (INR), developed by the World Health Organization in the early 1980s, is designed to eliminate problems in oral anticoagulant therapy caused by variability in the sensitivity of different commercial sources and different lots of thromboplastin to blood coagulation factor VII. The INR is used worldwide by most laboratories performing oral anticoagulation monitoring, and is routinely incorporated into dosage planning for patients receiving warfarin. Although the recent availability of sensitive PT reagents prepared from recombinant human tissue factor (rHTF) and synthetic phospholipids eliminated many of the earlier problems associated with the use of crude thromboplastin preparations, local instrument variability in the INR still remains a problem. Presently, the use of plasma calibrants seems the best solution to this problem. Standardizing the point-of-care instruments for INR monitoring is another dilemma faced by the industry. Ultimately, new generations of anticoagulant drugs may eliminate the need for laboratory monitoring of anticoagulant therapy.

Bleeding Complications to Long-Term Oral Anticoagulant Therapy

Objective: To evaluate the incidence of bleeding complications in recent randomized trials on oral anticoagetlant treatment for prevention of arterial thromboembolism. Data sources: International publications on studies of prevention. of arterial thromboembolism by oral anticoagulant therapy. Study selection and data extraction: Randomized trials an oral anticoagulant therapy in patients with atrial fibrillation, recent myocardial infarction, and prosthetic heart valves were selected. For comparison older nonrandomized studies were studied. Background: Oral anticoagulant drugs are recommended for primary prevention of thromboembolic events in patients with chronic atrial fibrillation, recent myocardial infarction, and prosthetic heart valves. Still many physicians hesitate to prescribe anticoagulant drugs, presumably for fear of bleeding complications. Results: In six recent trials of warfarin in patients with atrial fibrillation, the highest annual incidence of fatal and major bleeding was 0.8% and 2.0%, respectively. In patients treated with warfarin after a recent myocardial infarction, the incidence of fatal and major bleeding was 0.2% and 0.5% per year, respectively. The annual incidence of fatal and major bleeding in patients with prosthetic heart valves on warfarin treatment was found to be 1.4% and 5.2%, respectively. The mean incidence of fatal and major bleeding in patients on warfarin in these eight trials was 0.5% and 1.7% per year, respectively. The mean incidence of fatal and major bleeds in patients on placebo was 0.1% and 0.7% per year, respectively. In three randomized trials evaluating aspirin versus warfarin, the respective mean incidences of fatal and major bleeding during aspirin treatment were 0.2% and 0.8% per year. A remarkable decrease in the incidence of major bleeding complications to oral anticoagulant therapy is revealed by these trials as compared to previous studies. Reasons for this decline may be less intensive anticoagulant regimes, better control of anticoagulant therapy due to the introduction of the international normalized ratio, and careful pretreatment evaluation of risk factors for bleeding. In alI prospective trials of oral anticoagulation, the risk of bleeding was more than over-weighed by the beneficial effect on the incidence of stroke and peripheral thromboemboli.

Digital subtraction versus film-screen angiography for detecting acute pulmonary emboli: evaluation in a porcine model

PURPOSE

To compare the diagnostic performance of digital subtraction angiography (DSA) to that of film-screen angiography (FSA) for detecting acute pulmonary embolism (PE) in a porcine model.

MATERIALS AND METHODS

DSA and FSA were performed in 13 pigs before and after central venous administration of autologous emboli. Results were compared to findings at necropsy with use of ex vivo pulmonary angiography to guide pathologic sectioning. The sensitivity and predictive value of a positive case for detecting each embolus were computed for each pulmonary artery branch order and compared with use of 95% confidence intervals. Interobserver variability among three readers for individual PE detection was calculated.

RESULTS

Pathologic examination of the lungs revealed 100 total PEs (location by vessel order: 1st = 1, 2nd = 0, 3rd = 15, 4th = 32, > 5th = 52). On average, FSA review identified 72 (72%) emboli and DSA review, 65 (65%). There was no significant difference in sensitivity or predictive value of a positive case between DSA and FSA for detecting emboli (P > .05). There was similar agreement among readers for individual PE detection with DSA (mean, 84%) and FSA (mean, 80%).

CONCLUSION

The diagnostic performance of DSA is equivalent to that of FSA for detecting emboli in porcine PA branches. Interobserver agreement for individual PE detection is similar for both imaging techniques.

Application of treatment thresholds to diagnostic-test evaluation: an alternative to the comparison of areas under receiver operating characteristic curves

Diagnostic tests are often evaluated by comparison of the areas under receiver operating characteristic (ROC) curves. In this study the authors compared this approach with a more direct method that takes into account consequences of a diagnosis. Data from a prospective study of diagnosis of pulmonary embolism were used for a motivating example. Using multivariable logistic regression analysis, three diagnostic models were built and compared based on their ROC curves. Although model 1 (0.706) and model 2 (0.702) had the same ROC-curve area, they performed differently when risks and benefits of subsequent decisions were considered by applying the treatment probability threshold. Models 1 and 3 (0.611) had substantially different ROC-curve areas but performed similarly taking into account the therapeutic consequences. This demonstrates that comparison of diagnostic tests using the areas under the ROC curves may lead to erroneous conclusions about therapeutic usefulness. To correspond to daily practice, it would be more appropriate to also consider the clinical implications in evaluating diagnostic tests. This is made feasible by explicit definition and application of a treatment threshold.

Clinical utilization of the non-diagnostic lung scintigram

By virtue of the poor specificity of ventilation perfusion lung scintigraphy, a significant number of examinations for suspected pulmonary embolism (PE) result in a report which is neither normal nor high probability. These are unhelpful in establishing a firm clinical diagnosis. Patients with an indeterminate report should therefore undergo further investigation to establish the diagnosis particularly when treatment with anticoagulants is proposed. All lung scintigram reports issued over a 2-year period were reviewed and 102 indeterminate lung scintigram reports were identified. The case notes of 94 of these patients were examined and details of further investigation and management recorded. Fifty-one patients (55%) had no further radiological investigations and 19 (37%) of these were unequivocally categorized as having had pulmonary embolism by the referring clinician. Eighteen of these were treated with anticoagulation therapy. When patients proceeded to further radiological investigation then the result usually influenced the final clinical diagnosis. Clinicians frequently treat an intermediate report as the end point in investigation of suspected PE and consequently some patients may receive suboptimal management. By implementing a hospital wide policy of further investigation of non-diagnostic lung scintigrams, using a standard protocol, patient management could be improved.

Intracardiac thrombus formation in cardiac impairment: the role of anticoagulant therapy

The presence of intracardiac thrombus has been associated with many diseases and clinical states, although cardiac impairment is commonly also present. Despite this, there continues to be a lack of consensus on which patients with cardiac impairment should have anticoagulant therapy. This review discusses the relationship between thromboembolism and cardiac impairment secondary to ischaemic heart disease, and suggests possible mechanisms, methods of diagnosis and therapeutic strategies for anticoagulation in such patients. In particular, warfarin has been established as thromboprophylaxis in certain subgroups of patients with cardiac impairment secondary to ischaemic heart disease. A large-scale randomised controlled trial in ambulant patients with cardiac impairment to evaluate the effectiveness of anticoagulant therapy and antiplatelet therapy is, however, long overdue.

[Classical anticoagulant treatment of venous thromboembolic disease in cancer patients. Apropos of a retrospective study of 71 patients]

In order to evaluate the efficiency of classical anticoagulant therapy for venous thromboembolic disease in cancer patients, we retrospectively analysed 71 patients treated with intravenous heparin first and then with antivitamin K. After a mean follow-up of 185 +/- 25 days, 23 patients (33%) were dead; nine patients (12%) had suffered from major haemorrhagic complications, which were not fatal, four of which were due to heparin overdosage; 17 patients (24%) showed recurrent venous thromboembolic disease. According to univariate statistical analysis, risk of major bleeding was not associated with the presence of either thrombocytopenia, abnormal blood coagulation, metastases and/or any other hemorrhagic risk factors; recurrence of venous thromboembolic disease was not associated with the presence of other risk factors for venous thromboembolic disease, nor with the presence or absence of metastases and/or of ongoing chemotherapy. Such results suggest that classical anticoagulant therapy for venous thromboembolic disease in cancer patients is neither effective nor safe. The present retrospective study underlines needs for further prospective analyses in order to evaluate potential benefit from other therapeutic strategies, such as use of low molecular weight heparins and/or vena cava filter placement.

Risk of stroke during long-term anticoagulant therapy in patients after myocardial infarction

Myocardial infarction survivors have an increased risk of stroke, which is reduced with long-term anticoagulant therapy. However, an estimated 10-times increase in risk of bleeding during such treatment has been reported. We evaluated the risk of stroke in patients after a myocardial infarction and examined the relationship of the risk of intracranial hemorrhage or cerebral infarction and the intensity of anticoagulant therapy. The study population consisted of 3,404 post-myocardial infarction patients who took part in a randomized, double-blind, placebo-controlled trial. Patients were randomized to treatment with anticoagulants (international normalized ratio range, 2.8-4.8) or matching placebo. Mean follow-up was more than 3 years. The incidence of stroke analyzed on "intention-to-treat" was 0.7 per 100 patient-years in the anticoagulant patients against 1.2 in placebo, a hazard ratio of 0.60, with 95% confidence interval of 0.40 to 0.90. In the anticoagulation group, 15 patients had cerebral infarction and 17 an intracranial bleeding, 3 of which occurred after withdrawal of treatment. In the placebo group, the numbers were 43 and 2. Of the 14 intracranial bleeds during anticoagulation, 6 occurred at an international normalized ratio between 3.0 and 4.0 and 8 at greater than 4.0. These results confirm that long-term anticoagulant therapy substantially reduces the risk of stroke in post-myocardial infarction patients. The increased risk of bleeding complications associated with anticoagulant therapy is offset by a marked reduction in ischemic events. The risk of intracranial bleeding is directly related to the intensity of anticoagulant treatment.

Role of spiral volumetric computed tomographic scanning in the assessment of patients with clinical suspicion of pulmonary embolism and an abnormal ventilation/perfusion lung scan

BACKGROUND

A study was carried out to evaluate the potential place of spiral volumetric computed tomography (SVCT) in the diagnostic strategy for pulmonary embolism.

METHODS

In a prospective study 249 patients with clinical suspicion of pulmonary embolism were evaluated with various imaging techniques. In all patients a ventilation/perfusion (V/Q) scan was performed. Seventy seven patients with an abnormal V/Q scan underwent SVCT. Pulmonary angiography was then performed in all 42 patients with a non-diagnostic V/Q scan and in three patients with a high probability V/Q scan without emboli on the SVCT scan. Patients with an abnormal perfusion scan also underwent ultrasonography of the legs for the detection of deep vein thrombosis.

RESULTS

One hundred and seventy two patients (69%) had a normal V/Q scan. Forty two patients (17%) had a non-diagnostic V/Q scan, and in five of these patients pulmonary emboli were found both by SVCT and pulmonary angiography. In one patient, although SVCT showed no emboli, the angiogram was positive for pulmonary embolism. In one of the 42 patients the SVCT scan showed an embolus which was not confirmed by pulmonary angiography. The other 35 patients showed no sign of emboli. Thirty five patients (14%) had a high probability V/Q scan, and in 32 patients emboli were seen on SVCT images. Two patients had both a negative SVCT scan and a negative pulmonary angiogram. In one who had an inconclusive SVCT scan pulmonary angiography was positive. The sensitivity for pulmonary embolism was 95% and the specificity 97%; the positive and negative predicted values of SVCT were 97% and 97%, respectively.

CONCLUSIONS

SVCT is a relatively noninvasive test for pulmonary embolism which is both sensitive and specific and which may serve as an alternative to ventilation scintigraphy and possibly to pulmonary angiography in the diagnostic strategy for pulmonary embolism.

Oral anticoagulant treatment in a medical care district--a descriptive study

OBJECTIVE

To describe how oral anticoagulant therapy is performed in a defined catchment area in order to improve the quality of care.

DESIGN

Two study periods of 8 weeks were compared with reference to monitoring sites, i.e. hospital departments and primary health care centres.

SETTING

The health care district of Umeå in northern Sweden, with 125,300 inhabitants.

PARTICIPANTS

Patients on oral anticoagulant therapy at the department of Internal Medicine, Umeå University Hospital, in 1987 (n = 243) were compared with all patients treated in 1990 at health centres (n = 175) and at the department of Internal Medicine (n = 290) in the Umeå district.

MAIN OUTCOME MEASURES

The prevalence of treatment failures and complications was calculated per patient year, as well as the relative frequencies of patients within treatment recommendations.

RESULTS

80-83% of the patients were within treatment recommendations. Treatment failures were 3.6% of hospital patients, and 2.6% of primary care patients. Corresponding figures for bleeding complications were 8.9% and 5.1%, respectively. The differences are partly explained by differences in the studied groups, e.g. age, indications for treatment, and concomitant diseases.

Comparison of "accelerated" tissue plasminogen activator with streptokinase for treatment of suspected myocardial infarction

PURPOSE

A computerized decision analysis, based on the results of published clinical trials, assessed the risks, benefits, and costs of different thrombolytic regimens for suspected myocardial infarction (MI) throughout the likely range of clinical circumstances.

DATA SOURCE

Medline search and articles' bibliographies.

STUDY SELECTION

All studies reporting efficacy and side effects of thrombolysis.

DATA ANALYSIS

Life-expectancy outcomes of thrombolytic therapies for possible MI modeled by decision analysis.

RESULTS

The analysis allows a clinician to estimate the benefits, risks, and relative costs of thrombolytic therapies throughout the likely range of individual clinical circumstances. When applied, for example, to the average patient in ISIS-2, estimated gains are 150 quality-adjusted days of life (QALDs) from treatment with streptokinase (SK) and 255 QALDs with "accelerated" tPA (tPA). tPA costs $1,686 more than SK, taking into account the cost of lifelong care of the extra strokes incurred. Nevertheless, the chances of stroke above which thrombolysis is not preferred are 5.0% for SK and 8.0% for tPA, with tPA remaining the preferred treatment for six hours after symptom onset; thereafter, SK is marginally preferred, but at much lower cost. Both regimens are beneficial in older patients provided the chances of MI and death are "average" or greater.

CONCLUSION

When the chances of MI and death are known, decision analysis can be a useful bedside tool to guide thrombolytic therapy and subsequently, if needed, to review and defend the treatment decisions made.

Efficacy of long-term anticoagulant treatment in subgroups of patients after myocardial infarction

OBJECTIVE

To investigate the efficacy of long term oral anticoagulant treatment in subgroups of patients after myocardial infarction.

DESIGN

Analysis of the effect of anticoagulant treatment in subgroups of hospital survivors of myocardial infarction based upon age, gender, history of hypertension, previous myocardial infarction, smoking habits, diabetes mellitus, Killip class, anterior location of infarction, thrombolytic therapy, and use of beta blockers.

SUBJECTS

Participants of a multicentre, randomised, double blind, placebo controlled trial that assessed the effect of oral anticoagulant treatment on mortality as well as cerebrovascular and cardiovascular morbidity in 3404 hospital survivors of acute myocardial infarction.

MAIN OUTCOME MEASURES

The effect of anticoagulant treatment on recurrent myocardial infarction, cerebrovascular events, and vascular events (the composite endpoint of reinfarction, cerebrovascular event, and vascular death).

RESULTS

Long term anticoagulant treatment was associated with a reduction in mortality of 10% (95% confidence interval -11% to 27%), recurrent myocardial infarction of 53% (41% to 62%), cerebrovascular events of 40% (10% to 60%) and vascular events of 35% (24% to 45%). Treatment effect with respect to recurrent myocardial infarction was comparable among all subgroups of patients. Although treatment effect appeared to be somewhat smaller in females than in males (-11% v -45%), and in patients with diabetes compared to those without (-14% v -42%) with respect to vascular events, none of these differences reached statistical significance. In multivariate analysis, more advanced age, previous myocardial infarction, diabetes mellitus, and heart failure during admission were independently associated with increased incidence of cardiovascular complications.

CONCLUSIONS

The relative benefit of long term anticoagulant therapy in survivors of myocardial infarction is not modified by known prognostic factors for cardiovascular disease.

Acute gastrointestinal haemorrhage in anticoagulated patients: diagnoses and response to endoscopic treatment

The underlying diagnosis and clinical course of 52 patients who presented with severe acute gastrointestinal haemorrhage while taking the anticoagulant warfarin is reviewed. A bleeding site was identified in 83% of cases, only slightly fewer than the 92% found in a control of group of 710 patients not taking warfarin who presented in the same four year period. The degree or duration of anticoagulation was unrelated to the frequency of establishing a diagnosis. The commonest diagnosis was peptic ulcer (25 cases) and endoscopic treatment by injection or heater probe was attempted in 23 of these. The outcome in this subgroup was compared with that in 50 closely matched control subjects who had similar risk factors for rebleeding from peptic ulcer. Permanent haemostasis was achieved in (91%) of the anticoagulated and in 92% of the control patients. There were no complications related to endoscopy. Patients who present with acute gastrointestinal haemorrhage while taking warfarin usually bleed from mucosal disease. They should be endoscoped after resuscitation and those with major bleeding from a peptic ulcer should be offered endoscopic treatment.

Anticoagulant therapy in deep venous thrombosis. A randomized controlled study

Ninety patients with venographically proven deep venous thrombosis(DVT) but without clinical signs of pulmonary embolism(PE) were randomized into two different treatment regimens to compare the safety and efficacy of continuous intravenous heparin and oral anticoagulant(AC) treatment versus non-AC treatment. All patients in the two treatment groups were actively mobilized from the day of admission and wore graduated compressing stockings. In the non-AC-group the patients were treated with phenylbutazone for ten days. Treatment with heparin was maintained for 6 days and oral AC treatment was given from the third day and continued for 3 months. Venography was repeated after 30 days. A perfusion-ventilation lung scan was performed on day 1-2, 10 and 60. In fifty-nine patients a revenography was performed, twenty nine in the AC-group and thirty in the non-AC group. For distal veins regression was found in nine and eight respectively (4.4% in favour of AC, 95% confidence limit 27.5% to -18.7%) and in proximal veins regression was found in five and eight, respectively (10.9% in favour of AC, 95% confidence limit 32.0% to -10.1%). No difference in lung scans was found after 10 days (0.8% in favour of AC, 95% confidence limit 21.5% to -19.9%) or after 60 days (3.3% in favour of non-AC treatment, 95% confidence limit 21.8% to -28.5%). In the AC group the incidence of bleeding complications was 8.3%. No side-effects of phenylbutazone was found. The present controlled clinical study demonstrated no effect of AC-treatment on DVT progression in actively mobilized patients wearing graduated compressing stockings when compared to a non-AC treated group receiving analgetic therapy with phenylbutazone. However, the patient population of the study is relatively small with wide confidence intervals for differences between groups. Before more general recommendations can be made, a large scale placebo-controlled study is needed to evaluate the possible effect of AC-treatment in DVT patients, who can be mobilized from the first day.

Venous thromboembolism in neurosurgery and neurology patients: a review

Thromboembolism is a common problem in neurosurgery and neurology patients. Within this diverse population are subpopulations of patients with varying degrees of thromboembolic risk: low, moderate, and high. Patients at substantial risk for deep vein thrombosis and pulmonary embolism include those with spinal cord injury, brain tumor, subarachnoid hemorrhage, head trauma, stroke, and patients undergoing a neurosurgical operation. There are prophylactic strategies that can be applied to these various risk groups that will dramatically reduce the incidence of thromboembolism. The risk of pulmonary embolism or fatal pulmonary embolism typically exceeds the risk of severe or fatal bleeding from adequate prophylaxis, and these techniques should be applied on a routine basis. To adequately care for patients with deep venous thrombosis and pulmonary embolism, the physician requires a thorough understanding of the methods of diagnosis, the pharmacokinetics of heparin and warfarin, and a knowledge of their role in the treatment strategies that have proven efficacy and safety. In addition, an awareness of the low molecular weight heparins and heparinoids is becoming essential. These new agents have a potentially promising role in both the prophylaxis and treatment of patients with neurological disease. The principles concerning the prophylaxis, diagnosis, and clinical management of venous thromboembolic disease in neurosurgery and neurology patients are dealt with in this review.

Prophylactic oral anticoagulation in nephrotic patients with idiopathic membranous nephropathy

Whether the high incidence of thromboembolic events in nephrotic patients with membranous nephropathy justifies prophylactic administration of oral anticoagulants remains controversial. We used a Markov-based decision analysis model, explicitly considering the consequences of recurrent embolic and bleeding events to quantify the risk-benefit trade-offs of: (1) prophylactic therapy, in which oral anticoagulation was started at the time of diagnosis of nephrotic syndrome (before any thromboembolic event); and (2) anticoagulant therapy, in which treatment was started after the first clinical thromboembolic event. We assumed that anticoagulant therapy was discontinued if there was remission of the nephrotic syndrome. The overall number of fatal emboli prevented by prophylactic anticoagulants exceeded the one of fatal bleeding events for all clinically meaningful ranges of the following parameters: nephrotic syndrome duration, incidence of thromboembolic events, likelihood of embolization, and mortality rates of embolic and bleeding events. For a hypothetical 50-year-old patient who remained nephrotic for 2 years, prophylactic anticoagulation yielded a gain representing 2.5 months of quality-adjusted life expectancy. We conclude that for nephrotic patients with membranous nephropathy, the benefits of prophylactic administration or oral anticoagulants outweigh the risks.

Extracranial-intracranial saphenous vein bypass for carotid or vertebral artery dissections: a report of six cases

The management of carotid or vertebral artery dissections has generally been either conservative (with anticoagulation) or surgical (by proximal ligation or trapping procedures). However, identification and management of those patients with a high risk of stroke recurrence have been difficult. Six patients with carotid or vertebral artery dissections underwent a total of seven surgical procedures involving intracranial interpositional saphenous vein bypass grafts anastomosed distally beyond the point of dissection with trapping of the intermediate diseased section of the artery. It is suggested that this procedure be used in patients who have bilateral carotid or vertebral artery disease, persistent angiographic abnormalities (particularly aneurysms), or recurring ischemic events while undergoing anticoagulation therapy, or in whom anticoagulation is undesirable. This procedure has benefits over current surgical options because of the maintenance of high flow, the avoidance of abnormal watershed areas of flow, and the elimination of the risk of emboli. The procedure is compared to previous techniques of extracranial-intracranial bypass.

The use of expected value as an aid to decisions regarding anticoagulation in patients with atrial fibrillation

BACKGROUND

The method described provides a rational means for determining whether to institute chronic anticoagulation to prevent stroke in patients with chronic atrial fibrillation under a variety of clinical circumstances.

SUMMARY OF COMMENT

The concept of expected value is used in conjunction with data from clinical studies to define the net value of anticoagulation to the patient. A full year of anticoagulation is warranted in patients with recent stroke or transient ischemic attack thought to be due to cardiogenic embolism who feel that stroke is a very serious event with nearly as much disvalue as death. If stroke has a lesser degree of negative value to the patient, or it is uncertain whether the stroke was in a large-vessel distribution, or it is uncertain whether a large-vessel distribution stroke was due to cardiogenic embolism, 6 months or less of anticoagulation may be warranted. Indefinite anticoagulation is justifiable in most patients with chronic atrial fibrillation without a history of stroke or transient ischemic attack but may be contraindicated in certain patients at extremely low risk for embolism and in patients who place a low value on stroke relative to death and who have a modest increase in risk for fatal hemorrhage.

CONCLUSIONS

The method described provides a means readily usable by clinicians to make anticoagulation decisions in patients with chronic atrial fibrillation that will address risk-benefit tradeoffs with somewhat greater precision than current approaches.

Anticoagulant-related bleeding: clinical epidemiology, prediction, and prevention

OBJECTIVE

To review (1) the clinical epidemiology of bleeding during anticoagulant therapy with heparin or warfarin, (2) data useful in estimating the risk for bleeding in individual patients, and (3) the efficacy of methods for its prevention.

METHODS

Relevant literature was identified by a computerized search of the Medline database and by review of the bibliographies of original and review articles. Studies were classified according to their design. Estimates of the risk for bleeding during anticoagulant therapy, compared with the risk without therapy, were obtained from randomized trials. Estimates of the frequency of bleeding during the course of anticoagulant therapy and information about risk factors for bleeding were obtained primarily from longitudinal studies of inception cohorts of patients followed from the start of therapy.

MAIN RESULTS

The average daily frequencies of fatal, major, and major or minor bleeding during heparin therapy were 0.05%, 0.8%, and 2.0%, respectively; these frequencies are approximately twice those expected without heparin therapy. The average annual frequencies of fatal, major, and major or minor bleeding during warfarin therapy were 0.6%, 3.0%, and 9.6%, respectively; these frequencies are approximately five times those expected without warfarin therapy. The risk for anticoagulant-related bleeding is highest at the start of therapy: during warfarin therapy, the risk for major bleeding during the first month of therapy is approximately 10 times the risk after the first year of therapy. An individual patient's risk for major anticoagulant-related bleeding can be estimated on the basis of specific risk factors such as the intensity of the anticoagulant effect achieved and the presence of serious comorbid diseases, especially cerebrovascular, kidney, heart, and liver disease; older age and concurrent medicines may also be independent risk factors. Major bleeding most often affects the gastrointestinal tract, soft tissues, and urinary tract. Diagnostic evaluation of gastrointestinal bleeding and gross hematuria leads to identification of previously unknown lesions in approximately one-third of cases, even when the prothrombin time is elevated. Intracranial bleeding is rare, but it is frequently fatal. The frequency of bleeding during warfarin therapy is reduced by less intense therapy achieving a prothrombin time with an International Normalized Ratio of 2.0 to 3.0, which is efficacious for most indications.

CONCLUSION

Anticoagulant-related bleeding is common and often serious. The risk for bleeding can be estimated in an individual patient, giving the primary physician a quantitative basis for weighing the risks and benefits of therapy and for optimizing patient management. The frequency of anticoagulant-related bleeding is reduced by less intense warfarin therapy. Future studies should evaluate new approaches to management that may further reduce complications while maintaining efficacy.

Management and prevention of thromboembolic events in patients with cancer-related hypercoagulable states: a risky business

OBJECTIVE

To determine the optimal strategy for managing and preventing thromboembolic events in malignancy-associated hypercoagulable states.

DESIGN

A Markov-based decision and cost-effectiveness analysis was performed. The authors explicitly considered consequences of embolic and bleeding events, filter complications, and cancer-related excess mortality. Data were drawn from the current literature. The main outcome measure for each strategy was the quality-adjusted life expectancy and the total average variable costs.

SUBJECTS

Patients with advanced malignancies prone to develop thromboembolic events, patients with acute proximal deep venous thrombosis (DVT), and patients who have survived a first episode of pulmonary embolism (PE).

INTERVENTIONS

The authors considered three different interventions: 1) OBSERVATION, in which neither anticoagulant therapy nor filter placement is pursued, 2) ANTICOAGULATION, in which long-term anticoagulant therapy is started immediately, and 3) VENA CAVAL FILTER.

MAIN RESULTS

Vena caval filter was the preferred strategy for every malignancy studied, yielding an 11% gain in quality-adjusted life expectancy, compared with observation, for patients with acute DVT, and an 18% gain for patients having survived a PE. Anticoagulant therapy yielded gains of 9% and 16%, respectively. Compared with anticoagulant therapy, filter was less costly due to the avoidance of additional expenses incurred by bleeding events. Prophylactic therapy was the least effective of the three strategies examined.

CONCLUSIONS

Vena caval filter placement and long-term anticoagulation therapy yield similar outcomes in the setting of cancer-related hypercoagulable states. However, filter insertion is less expensive than anticoagulation. Given the short life expectancy and morbidity of patients with end-stage malignancy, patient preferences for health states must be considered in the decision-making process. If active treatment is pursued, vena caval filter should be used as a primary therapy. Prophylactic therapy is not warranted in any circumstance.

Low incidence of stroke in ambulatory patients with heart failure: a prospective study

The current study was undertaken to determine prospectively the risk of cerebral thromboembolism and the prognostic significance of left ventricular thrombus in ambulatory patients with chronic congestive heart failure. A total of 264 ambulatory patients (mean age 62 years, mean left ventricular ejection fraction 27%) were followed prospectively for 24 +/- 9 months to determine the incidence of nonhemorrhagic stroke, transient ischemic attack, and mortality. Two-dimensional echocardiographic studies, performed for clinical indications other than previous systemic thromboembolism in 109 patients, were analyzed to relate the presence of left ventricular thrombus to subsequent outcome. Nine cerebral thromboembolic events occurred in 264 patients during the two-year mean follow-up period, yielding a rate of 1.7 thromboembolic events per 100 patient-years of follow-up. Known risk factors for stroke (hypertension, diabetes mellitus, and/or atrial fibrillation) were present in all nine patients with cerebral thromboembolic events. The 109 patients with echocardiographic studies had more severe heart failure than patients without echocardiographic studies (functional class 2.6 vs 2.1, p < 0.01), greater risk of a thromboembolic event (2.4 vs 1.4 events/100 patient-years of follow-up, p < 0.01), and higher mortality (21.3 vs 5.5 deaths/100 patient-years, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Newer concepts in the medical management of patients with congestive heart failure

Congestive heart failure (CHF) remains a major cause of morbidity and mortality in the United States, especially among the elderly. Although an underlying disturbance in cardiac function can be identified in most patients, manifestations of the disease are greatly influenced by other factors, particularly neurohumoral and peripheral adaptive responses which occur secondary to impaired cardiac function. The renin-angiotensin system (RAS) is integrally involved in the pathophysiology of CHF. Originally considered a humoral system, the RAS is now known to exist and operate within cardiac and vascular tissues. The importance of tissue-specific renin-angiotensin systems in CHF is presently under investigation. Most patients with symptomatic CHF benefit from the administration of an ACE inhibitor. Certain asymptomatic patients, such as those with severe left ventricular (LV) dysfunction and those who are at high risk for LV remodeling after anterior wall myocardial infarction, may also benefit from ACE inhibitor therapy. Diuretics and nitrates improve symptoms and often cardiac output in many patients with CHF. Although many new inotropic agents have been tested in CHF patients, none appear clinically superior to digitalis glycosides. The efficacy of digitalis glycosides in CHF may in part result from sympathoinhibitory properties such as the activation of baroreceptor mechanisms. Despite the fact that many CHF patients die from arrhythmias, treatment of asymptomatic ventricular arrhythmias in these patients is not recommended. Patients with symptomatic or sustained ventricular arrhythmias are best treated by a physician experienced in cardiac electrophysiology. Therapy with beta-blocking drugs for CHF patients is controversial. Anticoagulants are recommended for selected patients with CHF. Finally, exercise therapy may improve functional capacity in some patients with CHF through its effects on peripheral blood vessels and skeletal muscle tissues.

Whither the rationale for thrombolytic agent administration? A retrospective review of traditional intuitive decision-making using a decision analysis model

Of 50 consecutive patients admitted to Nenagh Hospital coronary care unit 50 per cent did not develop a myocardial infarction. Only 10 patients had definite evidence of infarction on admission. Of the 40 remaining patients, only 15 subsequently developed electrocardiographic and enzymatic confirmation of infarction. Streptokinase was administered to 5 patients who did not infarct, and was not given to 10 patients who did. These decisions to use or withhold thrombolytic therapy were retrospectively reviewed using a computer programme incorporating a decision analysis of the benefits and risks of thrombolysis. The programme examined four scenarios that used different estimates of the chance of death from infarction (pdiMI), and different safety profiles of thrombolytics. The scenario that assumed the worst safety profile and estimated pdiMI from patient age would have recommended thrombolytic treatment to the most with, and to the least without, acute infarction (i.e. 60 per cent of patients with an infarct and 8 per cent without an infarct would have been treated). Depending on the scenario assumed, the traditional intuitive method of decision-making gained from 0.08 and 0.25 quality adjusted life years (QALY's) for the average patient. Had decision analysis been used to guide these decisions these gains would have been enhanced by from 0.21 to 0.28 QALY's per patient, regardless of scenario used.