Warfarin maintenance dosing patterns in clinical practice: implications for safer anticoagulation in the elderly population.

Background: The use of anticoagulant therapy is expanding among the elderly population, in part because of the increasing prevalence of atrial fibrillation. Published data describing the warfarin maintenance dose requirements for this age group are limited. Because warfarin therapy is often initiated in the outpatient setting where significant barriers to daily monitoring exist for this patient population, a better understanding of the factors that predict lower dose requirements may reduce the risk of unanticipated over-anticoagulation and hemorrhage.

Are brand-name and generic warfarin interchangeable? Multiple n-of-1 randomized, crossover trials.

Background: Warfarin is a commonly used anticoagulant in North America. Several generic formulations have been approved, raising concern over the safety and efficacy of these products compared with brand-name Coumadin.

Objective: To ensure that generic warfarin products can be safely interchanged with Coumadin.

Systematic overview of warfarin and its drug and food interactions.

Background: Warfarin is a highly efficacious oral anticoagulant, but its use is limited by a well-founded fear of bleeding. Drug and food interactions are frequently cited as causes of adverse events with warfarin. We provide an updated systematic overview of the quality, clinical effect, and importance of these reported interactions.

Does the type of hormone replacement therapy influence the risk of deep vein thrombosis? A prospective case-control study.

Background: Although hormone replacement therapy (HRT) is associated with an increased risk of deep vein thrombosis (DVT), it is not clear if the risk differs in users of combined estrogen-progestin HRT and estrogen-only HRT.

Methods: We prospectively studied postmenopausal women with suspected DVT in whom HRT use status was ascertained and who subsequently had objective diagnostic testing to confirm or exclude DVT. Cases were patients with idiopathic DVT, in whom there were no DVT risk factors, and controls were patients without DVT, in whom there were also no DVT risk factors.

Antiphospholipid antibody syndrome: recent findings on managing this challenging condition.

Patients with antiphospholipid syndrome can suffer recurrent thrombosis that is very difficult to manage. Recent research has demonstrated that high-intensity anticoagulation is not superior to standard therapy. Basic questions about the nature and treatment of this syndrome remain unanswered.

Perioperative anticoagulation for patients with mechanical heart valves: a survey of current practice.

Background: Patients with mechanical heart valves (MHV) require temporary interruption of warfarin when undergoing invasive procedures. Current guidelines addressing this subject are discordant because there is no high quality evidence to support any single management strategy. We tested the hypothesis that there is significant practice variation amongst clinicians caring for patients with MHV who require temporary cessation of their warfarin therapy.

A randomized trial of diagnostic strategies after normal proximal vein ultrasonography for suspected deep venous thrombosis: D-dimer testing compared with repeated ultrasonography.

Background: With suspected deep venous thrombosis and normal results on proximal vein ultrasonography, a negative d-dimer result may exclude thrombosis and a positive D-dimer result may be an indication for venography.

Objective: To evaluate and compare the safety of 2 diagnostic strategies for deep venous thrombosis.

Design: Randomized, multicenter trial.

Perioperative anticoagulation in patients with mechanical heart valves undergoing elective surgery: results of a survey conducted among Korean physicians.

The optimal perioperative anticoagulation management in patients on warfarin therapy is poorly defined due to the lack of randomized trials. Because guidelines are heterogeneous, it was hypothesized that "treatment strategies are not uniform in clinical practice". Between February 2003 and May 2003, a questionnaire with 4 different clinical scenarios was distributed to physicians by e-mail, or direct contact was made by a survey monitor.

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

Background: The post-thrombotic syndrome is a chronic, poorly understood complication of deep venous thrombosis (DVT).

Objectives: To evaluate predictors of the post-thrombotic syndrome, including intensity of long-term anticoagulation, and to assess the impact of the post-thrombotic syndrome on quality of life.

Patients And Methods: The setting was 13 Canadian hospitals and one US hospital.

Video laparoscopic surgery: is out-of-hospital thromboprophylaxis necessary?

Despite widespread use of laparoscopic procedures, no adequate data are available to support specific recommendations for venous thromboprophylaxis in patients undergoing laparoscopic surgery. This prospective, randomized trial is the first to be designed to evaluate a regimen of out-of-hospital thromboprophylaxis after laparoscopic surgery. Consecutive patients admitted for laparoscopic surgery were considered for the study.

Propagation of stress fracture of the patella.

Anterior knee pain in athletes is common and usually self limited. There should be a high index of suspicion and low threshold for special imaging in cases with acute onset and specific tenderness. The risk of propagation of stress fracture of the patella in athletes is highlighted.

Oral vitamin K produces a normal INR within 24 hours of its administration in most patients discontinuing warfarin.

A randomized, blinded study in 30 patients was undertaken. This study found that low dose oral vitamin K was more effective than placebo when used to correct the INR in patients who are discontinuing warfarin. Larger studies will be required to determine if the use of oral vitamin K, for example in patients who are temporarily discontinuing warfarin to undergo interventional procedures, is safe and effective.

Managing oral anticoagulant therapy in patients with mechanical heart valves undergoing elective surgery: results of a survey conducted among Italian physicians.

The optimal perioperative anticoagulation management in patients on warfarin therapy is poorly defined because of the lack of randomized trials. Because guidelines are heterogeneous, we hypothesized that treatment strategies are not uniform in clinical practice. During the Annual Meeting of the Italian Federation of Anticoagulation Clinics, a questionnaire with four different clinical scenarios was distributed.

Neither baseline tests of molecular hypercoagulability nor D-dimer levels predict deep venous thrombosis in critically ill medical-surgical patients.

Objective: Predicting patients who are harboring asymptomatic deep venous thrombosis (DVT), or who are at particular risk of developing DVT, is a desirable clinical goal since prevention or early treatment of DVT might reduce the risk of fatal pulmonary embolism. Thus validation of simple laboratory tests that reliably predict venous thromboembolism (VTE) would be clinically very important. Tests that might be useful for these applications include markers of hypercoagulability (predicting patients at risk of DVT) and D-dimer (predicting which patients may have acute DVT).

Safety and efficacy of low molecular weight heparins for hemodialysis in patients with end-stage renal failure: a meta-analysis of randomized trials.

Low molecular weight heparins (LWMH) are the preferred initial treatment for many thromboembolic disorders but are renally excreted and relatively contraindicated in patients with renal failure because of concerns of increased bleeding risks. The purpose of this study was to evaluate the safety and efficacy of LMWH compared with unfractionated heparin (UFH) for preventing thrombosis of the extracorporeal dialysis circuit. Studies were identified with the use of MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and FirstSearch; reference lists were reviewed; and pharmaceutical companies were contacted.

Evidence based treatment of the antiphospholipid syndrome II. Optimal anticoagulant therapy for thrombosis.

Introduction: Current consensus recommendations suggest that patients with antiphospholipid antibodies (APLA) are at high risk of recurrent arterial or venous thromboembolism (VTE) despite warfarin administered to achieve an international normalized ratio (INR) of 2.0 to 3.0.

Anticoagulant therapy for the thrombotic complications of the antiphospholipid antibody syndrome.

Patients with antiphospholipid antibodies (APLA) are at risk of arterial thromboembolism (ATE) or venous thromboembolism (VTE). The true strength of the association between APLA and first TE is unknown as there are no prospective studies of a large, well-characterized inception cohort of matched patients with and without APLA. Thus, evidence-based treatment recommendations for primary prophylaxis of TE in such patients cannot be made.

Methodology for guideline development for the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy.

This article describes the methodology for the Seventh American College of Chest Physicians (ACCP) Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Guideline authors began by specifying the population, the intervention and alternative, and the outcomes for each clinical question, and defined the criteria for eligible articles, including methodological criteria, for each recommendation. Librarians, in collaboration with guideline authors and methodologists, conducted systematic searches for evidence.

Patient preferences for capillary vs. venous INR determination in an anticoagulation clinic: a randomized controlled trial.

Background: Patients who are receiving warfarin therapy require frequent blood testing to monitor the intensity of anticoagulation. Although previous studies suggest that capillary blood monitoring of the international normalize ratio (INR) is rapid and reliable, patient preferences for the method of blood drawing have not been investigated.

Methods: We performed a randomized controlled trial of patients attending an anticoagulation clinic in which patients were randomly allocated to undergo capillary or venous INR monitoring.

Patients with severe sepsis vary markedly in their ability to generate activated protein C.

Activated protein C (APC) supplementation significantly reduces mortality in patients with severe sepsis, presumably by down-regulating coagulation, inflammation, and apoptosis. In vivo, endogenous APC is generated from protein C (PC) "on demand" in response to elevated thrombin levels. Thrombomodulin and endothelial cell protein C receptor are endothelial receptors required to generate APC endogenously.

Oral anticoagulant initiation: rationale for the use of warfarin dosing nomograms.

Oral anticoagulants prevent thrombosis however they are associated with bleeding. The risk of both bleeding and thrombosis is increased when the International Normalized Ratio (INR) is outside the desired therapeutic range. Hence, oral anticoagulants should be administered with the intention of maximizing the "time within the therapeutic range.