Clinical Predictors for Venous Thromboembolism in Patients With a History of Thrombosis (PREDICTORS)

Completed

Conditions: Deep Vein Thrombosis
Thromboembolic Disease Recurrent
Recurrent Thromboembolic Disease
Pulmonary Embolism
Venous Thromboembolism

Registration Number: NCT02297373

Lead Sponsor: Ottawa Hospital Research Institute

Brief Summary: Patients with a history of blood clots are at risk of developing additional clots in the future. Doctors use a tool called a clinical decision rule to tell them how likely it is that a patient has a blood clot and if they should have further testing to look for the clot. This tool may cause doctors to over-diagnosis a recurrent clot because the symptoms may be left over from the previous clot. Correctly diagnosing a recurrent blood clot is very important since there are risks associated with both over-diagnosis and under-diagnosis. If a recurrent blood clot is missed (under-diagnosis) the patient is at risk of death from a clot in the lungs. If blood thinners are prescribed when they are not needed (over-diagnosis), the patient may have to take blood thinners for their lifetime and risk having serious bleeding.

Detailed Description: Several tools have been developed to standardize the diagnostic management of a suspected first blood clot. One of these tools is the use of a clinical decision rule. Clinical decision rules have been designed to help clinicians make diagnostic and therapeutic decisions at the bedside. A score is computed on the presence of some criteria from the patient's medical history, clinical signs and symptoms. The score provides the probability of a blood clot. The rules can be used in combinations with a simple blood test - called D-dimer - to identify patients at low risk who don't require diagnostic imaging testing. Benefits include reduced costs, length in hospital and radiation exposure.

Patients with prior blood clots have been shown to be less likely to benefit from the non-invasive testing. Therefore, they often need to undergo imaging tests, which are frequently difficult to interpret in patients with prior blood clots since residual clots are often present and are difficult to distinguish from a recurrent clot.

The objective of this study is to try to prospectively assess the role of existing clinical decision rules in patients with prior blood clots, and to attempt to improve them in order to increase the yield of non-invasive testing and to reduce the risk of over-diagnosis with imaging tests.

With respect to this study, clots within the deep veins of the legs are called deep vein thrombosis (DVT), while clots in the lungs are called pulmonary embolism (PE).

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 744

Inclusion Criteria

Outpatients with clinically suspected acute recurrent DVT or PE regardless of whether the previous event was a DVT or PE
Age ≥18 years old
Willing and able to give informed consent

Exclusion Criteria

Life expectancy less than 3 months
Suspicion of upper extremity thrombosis or thrombosis at an unusual site (e.g. cerebral or abdominal venous thrombosis)
Previous VTE was distal DVT or subsegmental PE
Suspected recurrent VTE is asymptomatic
Previously enrolled in this study

Study & Design

Study Type: OBSERVATIONAL

Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Validation of the Wells DVT Clinical Decision Rule	Day 0 (at time of suspected recurrent DVT)	The Wells DVT Clinical Decision Rule (CDR) assigns a score from -2 to +9 based on clinical variables (e.g., active cancer, limb swelling, localized tenderness, prior history of DVT, alternative diagnosis as likely or more likely than DVT). In this study, the 3-level Wells DVT CDR was applied prospectively at presentation (Day 0) to participants with suspected recurrent DVT, using data collected from patient history and physical examination. Scores classify patients into low (≤0), moderate (1-2), or high (≥3) probability of DVT. Higher scores indicate greater probability of recurrent DVT. The outcome measure was the rate of confirmed recurrent DVT events within each Wells category, confirmed by objective imaging and adjudicated by an independent committee.
Validation of the Wells PE Clinical Decision Rule	Day 0 (at time of suspected recurrent PE)	The 3-level Wells PE score (range 0-12.5) was calculated from history and exam at the index visit. Scores ≤4 = PE unlikely, \>4 = PE likely. Higher scores indicate greater likelihood of PE. The outcome is the proportion with confirmed recurrent PE at the index diagnostic work-up, adjudicated by blinded review of imaging.
Validation of the Geneva PE Clinical Decision Rule	Day 0 (at time of suspected recurrent PE)	The revised Geneva score (range 0-22) was calculated from history and exam at the index visit. Scores 0-3 = low, 4-10 = intermediate, ≥11 = high probability. Higher scores indicate greater likelihood of PE. The outcome is the proportion with confirmed recurrent PE at the index diagnostic work-up, adjudicated by blinded review of imaging.

Secondary Outcome Measures

Name	Time	Method
All-Cause Mortality Within 90 Days of Index Visit	From enrollment (Day 0) through Day 90 follow-up for those not diagnosed with a confirmed recurrent VTE at enrollment	Number of participants who died from any cause from enrollment (Day 0) through Day 90 follow-up for those without confirmed recurrent VTE at enrollment.
Accuracy of Current D-dimer Testing Methods	Day 0 (at time of suspected recurrent VTE)	D-dimer testing at the index visit was performed using the institutional cut-off for positivity in place during the study period (2014-2019). Results were classified as positive or negative. The outcome is the proportion with confirmed recurrent VTE in each test category at the index diagnostic work-up, adjudicated by blinded review of imaging.
Rate of Confirmed Events Using Current Wells DVT/Wells PE/Geneva PE in Participants on Anticoagulant Therapy	Day 0 (at time of suspected recurrent VTE)	The Wells DVT, Wells PE, and Geneva PE scores were calculated at the index visit in participants on anticoagulation. Score ranges and cut-offs as per respective rules. The outcome is the proportion with confirmed recurrent VTE in each risk category at the index diagnostic work-up, adjudicated by blinded review of imaging.

Trial Locations

Locations (9): Nova Scotia Health Authority
🇨🇦
Halifax, Nova Scotia, Canada
Hamilton Health Sciences Centre
🇨🇦
Hamilton, Ontario, Canada
Lawson Health Research Institute
🇨🇦
London, Ontario, Canada
The Ottawa Hospital
🇨🇦
Ottawa, Ontario, Canada
Hopital Montfort
🇨🇦
Ottawa, Ontario, Canada
Humber River Hospital
🇨🇦
Toronto, Ontario, Canada
Sir Mortimer B. Davis Jewish General Hospital
🇨🇦
Montreal, Quebec, Canada
Leiden University Medical Centre
🇳🇱
Leiden, Netherlands
Geneva University Hospital
🇨🇭
Geneva, Switzerland
Nova Scotia Health Authority
🇨🇦Halifax, Nova Scotia, Canada