Clinical trial NCT00788736: Predicting Bleeding Risk on Anticoagulant Therapy for Venous Thromboembolism
Official title: Development and Validation of Clinical Prediction Rules for Bleeding for Patients on Anticoagulant Therapy for Venous Thromboembolism
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Venous Thromboembolism
Keywords: venous thromboembolism
long-term oral anticoagulant therapy
warfarin
bleeding risk
clinical prediction rule
predictors
deep vein thrombosis
pulmonary embolism
vitamin k antagonist
side effect
Lead sponsor: Ottawa Hospital Research Institute
Sponsor class: OTHER
Collaborators: name: Heart and Stroke Foundation of Ontario
name: Canadian Institutes of Health Research (CIHR)
First posted: 2008-11-11
Enrollment: 2537
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Outpatients being treated for venous thromboembolism

Brief summary: The main objective of the study is to develop or validate a clinical prediction rule for major bleeding in patients on oral anticoagulant therapy who have been safely anticoagulated without bleeding or venous thromboembolism (VTE) recurrence for at least 3 months since diagnosis and are being considered for long-term oral anticoagulant therapy.

Detailed description: Oral anticoagulant therapy for patients who are at risk of developing blood clotting problems is used by between 400,000-600,000 Canadians annually. The use of this drug represents the most common cause of patient adverse medical outcomes due to medical errors. Furthermore, many patients have adverse outcomes using these drugs because physicians are not able to predict which patients are likely to have bleeding outcomes. Much effort has gone into developing ways to predict which patients are at risk of clotting but almost no work has gone into ways of predicting which patients would be at high risk of bleeding. This information is required to balance off the risk-benefits and to enable physicians and patients to understand the risks and benefits of taking these medications. Our study will develop a tool that can be used to predict bleeding risk in patients taking oral anticoagulant therapy. It will enable more informed decision making by both physicians and patients and will result in better control of the use of these drugs. In addition, patients who are at risk for being difficult to accurately dose on oral anticoagulants will be identified through our study.

Eligibility criteria: Inclusion Criteria:

* \>=18 years old
* provoked or unprovoked venous thromboembolism
* objectively confirmed venous thromboembolism
* treated with an oral anticoagulant(vitamin K antagonist or new oral anticoagulant) for at least 3 months with plans to continue long-term
* if taking a vitamin K antagonist; INR target is between 2.0-3.0
* if taking a vitamin K antagonist; must have taken it for the last 3 consecutive weeks (minimum)

Exclusion Criteria:

* major bleeding while taking oral anticoagulants
* active bleeding at study enrollment
* active cancer - current or at the time of VTE diagnosis
* unable to provide written informed consent
* refusal to provide written informed consent

Primary outcomes:
measure: Major bleeding (International Society on Thrombosis and Haemostasis(ISTH) criteria)
timeFrame: ongoing for 3-7 years with follow-up phone calls at 6-month intervals
Secondary outcomes:
measure: Clinically relevant non-major bleeding (International Society on Thrombosis and Haemostasis(ISTH) criteria)
timeFrame: ongoing for 3-7 years with follow-up phone calls at 6-month intervals
measure: recurrent venous thromboembolism
timeFrame: ongoing for 3-7 years with follow-up phone calls at 6-month intervals
measure: death (all causes)
timeFrame: ongoing for 3-7 years with follow-up phone calls at 6-month intervals
Other outcomes:
Locations:
city: Burlington
country: United States
facility: Lahey Clinic
state: Massachusetts
city: Detroit
country: United States
facility: Henry Ford Health System
state: Michigan
city: Halifax
country: Canada
facility: Queen Elizabeth II Health Sciences Centre
state: Nova Scotia
city: Hamilton
country: Canada
facility: Hamilton General Hospital
state: Ontario
city: Hamilton
country: Canada
facility: Hamilton Health Sciences
state: Ontario
city: London
country: Canada
facility: London Health Sciences Centre
state: Ontario
city: Ottawa
country: Canada
facility: Ottawa Hospital Research Institute
state: Ontario
city: Montreal
country: Canada
facility: Montreal General Hospital
state: Quebec
city: Montreal
country: Canada
facility: Sir Mortimer B Davis Jewish General Hospital
state: Quebec
city: Montreal
country: Canada
facility: St. Mary's Hospital Centre
state: Quebec
city: Montreal
country: Canada
facility: Hopital du Sacre Coeur de Montreal
state: Quebec
city: Oxford
country: United Kingdom
facility: Oxford Haemophilia and Thrombosis Centre, Churchill Hospital
Study officials:
affiliation: Ottawa Hospital Research Institute
name: Phil S Wells, MD, MSc
role: PRINCIPAL_INVESTIGATOR
References: