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Trial record 21 of 590 for:    WARFARIN

Prolongation of the Interval Between Monitoring of Warfarin in Stable Patients

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ClinicalTrials.gov Identifier: NCT00356759
Recruitment Status : Completed
First Posted : July 26, 2006
Results First Posted : August 22, 2018
Last Update Posted : August 22, 2018
Sponsor:
Collaborator:
The Physicians' Services Incorporated Foundation
Information provided by (Responsible Party):
Sam Schulman, McMaster University

Study Type Interventional
Study Design Allocation: Randomized;   Intervention Model: Parallel Assignment;   Masking: Triple (Participant, Care Provider, Investigator);   Primary Purpose: Treatment
Conditions Atrial Fibrillation
Heart Valve Diseases
Venous Thrombosis
Intervention Drug: Dosing warfarin every 12 weeks, sham INRs 2 out of 3 times
Enrollment 250
Recruitment Details  
Pre-assignment Details  
Arm/Group Title Dose Assessment 4-weekly Dose Assessment 12-weekly
Hide Arm/Group Description INRs and dose assessments every 4 weeks true values, no sham INRs INRs and dose assessment 4-weekly, but 2 of 3 INRs are sham results, so dose assessment on true result is only 12-weekly
Period Title: Overall Study
Started 126 124
Completed 112 114
Not Completed 14 10
Reason Not Completed
Death             5             2
Withdrawal by Subject             2             2
Adverse Event             1             3
Lost to Follow-up             1             1
Intercurrent disease or persistent extre             5             2
Arm/Group Title Dose Assessment 4-weekly Dose Assessment 12-weekly Total
Hide Arm/Group Description INRs and dose assessments every 4 weeks true values, no sham INRs INRs and dose assessment 4-weekly, but 2 of 3 INRs are sham results, so dose assessment on true result is only 12-weekly Total of all reporting groups
Overall Number of Baseline Participants 126 124 250
Hide Baseline Analysis Population Description
All patients randomized
Age, Continuous  
Median (Full Range)
Unit of measure:  Years
Age Number Analyzed 126 participants 124 participants 250 participants
72
(29 to 93)
70
(23 to 92)
71
(23 to 93)
Sex: Female, Male  
Measure Type: Count of Participants
Unit of measure:  Participants
Number Analyzed 126 participants 124 participants 250 participants
Female
39
  31.0%
37
  29.8%
76
  30.4%
Male
87
  69.0%
87
  70.2%
174
  69.6%
Therapeutic INR range   [1] 
Measure Type: Number
Unit of measure:  Participants
Number Analyzed 126 participants 124 participants 250 participants
INR range 2.0-3.0 111 109 220
INR range 2.5-3.5 15 15 30
[1]
Measure Description: International normalized ratio (INR) is a standardized expression of the prothrombin time. Normal is 0.9-1.2. Therapeutic range is 2.0-3-0 for most patients, 2.5-3.5 for those with mechanical mitral valve or with mechanical aortic valve plus atrial fibrillation
1.Primary Outcome
Title Primary Outcome Measure: Time in Therapeutic Range
Hide Description Percent time in therapeutic range calculated by linear interpolation.
Time Frame 12 months
Hide Outcome Measure Data
Hide Analysis Population Description
Intention to treat population
Arm/Group Title Dose Assessment 4-weekly Dose Assessment 12-weekly
Hide Arm/Group Description:
INRs and dose assessments every 4 weeks true values, no sham INRs
INRs and dose assessment 4-weekly, but 2 of 3 INRs are sham results, so dose assessment on true result is only 12-weekly
Overall Number of Participants Analyzed 126 124
Mean (Standard Deviation)
Unit of Measure: percentage of time
74.1  (18.8) 71.6  (20.0)
2.Secondary Outcome
Title Secondary Efficacy Outcomes: Thromboembolic Events
Hide Description Number of patients with any objectively verified, independently adjudicated thromboembolic event during the 12-month study period
Time Frame 12 months
Hide Outcome Measure Data
Hide Analysis Population Description
Intention to treat
Arm/Group Title Dose Assessment 4-weekly Dose Assessment 12-weekly
Hide Arm/Group Description:
INRs and dose assessments every 4 weeks true values, no sham INRs
INRs and dose assessment 4-weekly, but 2 of 3 INRs are sham results, so dose assessment on true result is only 12-weekly
Overall Number of Participants Analyzed 126 124
Measure Type: Number
Unit of Measure: participants
1 0
3.Secondary Outcome
Title Secondary Safety Outcome: Major Bleeding
Hide Description Number of patients with any objectively verified, independently adjudicated major bleeding event during the 12-month study period. Major bleeding was defined according to the International Society on Thrombosis and Haemostasis (ISTH) criteria
Time Frame 12 months
Hide Outcome Measure Data
Hide Analysis Population Description
Intention to treat
Arm/Group Title Dose Assessment 4-weekly Dose Assessment 12-weekly
Hide Arm/Group Description:
INRs and dose assessments every 4 weeks true values, no sham INRs
INRs and dose assessment 4-weekly, but 2 of 3 INRs are sham results, so dose assessment on true result is only 12-weekly
Overall Number of Participants Analyzed 126 124
Measure Type: Number
Unit of Measure: participants
1 2
4.Secondary Outcome
Title Secondary Safety Outcome: Number of Patients With Extreme INR Results
Hide Description Secondary safety outcome is number of patients with at least one INR below 1.5 or above 4.4
Time Frame 12 months
Hide Outcome Measure Data
Hide Analysis Population Description
Intention to treat
Arm/Group Title Dose Assessment 4-weekly Dose Assessment 12-weekly
Hide Arm/Group Description:
INRs and dose assessments every 4 weeks true values, no sham INRs
INRs and dose assessment 4-weekly, but 2 of 3 INRs are sham results, so dose assessment on true result is only 12-weekly
Overall Number of Participants Analyzed 126 124
Measure Type: Number
Unit of Measure: participants
27 19
5.Secondary Outcome
Title Number of Extreme INR Results
Hide Description Number of INRs outside the range 1.5-4.4
Time Frame 12 months
Hide Outcome Measure Data
Hide Analysis Population Description
Intention to treat
Arm/Group Title Dose Assessment 4-weekly Dose Assessment 12-weekly
Hide Arm/Group Description:
INRs and dose assessments every 4 weeks true values, no sham INRs
INRs and dose assessment 4-weekly, but 2 of 3 INRs are sham results, so dose assessment on true result is only 12-weekly
Overall Number of Participants Analyzed 126 124
Measure Type: Number
Unit of Measure: Number of tests
27 17
6.Secondary Outcome
Title Patients With Dose Changes
Hide Description Number of patients with at least one change of maintenance dose during the 12-month study period
Time Frame 12 months
Hide Outcome Measure Data
Hide Analysis Population Description
Intention to treat
Arm/Group Title Dose Assessment 4-weekly Dose Assessment 12-weekly
Hide Arm/Group Description:
INRs and dose assessments every 4 weeks true values, no sham INRs
INRs and dose assessment 4-weekly, but 2 of 3 INRs are sham results, so dose assessment on true result is only 12-weekly
Overall Number of Participants Analyzed 126 124
Measure Type: Number
Unit of Measure: participants
70 46
Time Frame 12 months
Adverse Event Reporting Description Fatal events are reported as serious adverse events. Non-fatal major bleeding or thromboembolism are reported as serious adverse events. Minor bleeding events are reported as non-serious (other) adverse events.
 
Arm/Group Title 12-weekly INR 4-weekly INR
Hide Arm/Group Description Patients had INR every 4 weeks but only every thisrd INR was true; the other two were sham INRs dampened to be within or close to therapeutic range. Thus, true dose assessment was in practice performed every 12 weeks Patients had INR every 4 weeks and all results were true. Thus, true dose assessments were performed every 4 weeks.
All-Cause Mortality
12-weekly INR 4-weekly INR
Affected / at Risk (%) Affected / at Risk (%)
Total   2/124 (1.61%)      5/126 (3.97%)    
Show Serious Adverse Events Hide Serious Adverse Events
12-weekly INR 4-weekly INR
Affected / at Risk (%) # Events Affected / at Risk (%) # Events
Total   4/124 (3.23%)      7/126 (5.56%)    
Cardiac disorders     
Cardiac death   1/124 (0.81%)  1 3/126 (2.38%)  3
Gastrointestinal disorders     
Gastrointestinal bleeding  [1]  2/124 (1.61%)  2 1/126 (0.79%)  1
Infections and infestations     
Septic shock  [2]  0/124 (0.00%)  0 1/126 (0.79%)  1
Renal and urinary disorders     
Renal infarct  [3]  0/124 (0.00%)  0 1/126 (0.79%)  1
Respiratory, thoracic and mediastinal disorders     
Respiratory failure  [4]  1/124 (0.81%)  1 1/126 (0.79%)  1
Indicates events were collected by systematic assessment
[1]
Melena
[2]
Pancreatitis with fatal septic shock
[3]
Arterial embolism
[4]
Fatal respiratory failure
Show Other (Not Including Serious) Adverse Events Hide Other (Not Including Serious) Adverse Events
Frequency Threshold for Reporting Other Adverse Events 0%
12-weekly INR 4-weekly INR
Affected / at Risk (%) # Events Affected / at Risk (%) # Events
Total   7/124 (5.65%)      4/126 (3.17%)    
Eye disorders     
Subconjunctival bleeding  [1]  0/124 (0.00%)  0 1/126 (0.79%)  1
Gastrointestinal disorders     
Rectal bleeding  [2]  1/124 (0.81%)  1 1/126 (0.79%)  1
Renal and urinary disorders     
Hematuria  [3]  2/124 (1.61%)  2 1/126 (0.79%)  1
Respiratory, thoracic and mediastinal disorders     
Epistaxis  [4]  4/124 (3.23%)  4 1/126 (0.79%)  1
Indicates events were collected by systematic assessment
[1]
Subconjunctival eye bleeding that did not meet criteria for major bleeding
[2]
Bleeding from rectum bleeding that did not meet criteria for major bleeding
[3]
Urinary tract bleeding that did not meet criteria for major bleeding
[4]
Bleeding from the nose that did not fulfill criteria for major bleeding
Not a truly INR monitoring and dosing every 12 weeks, because patients were tested and contacted every 4 weeks for sham results and to remind of important factors for INR instability. Extreme INR results in the 12-week group were reported unblinded.
Certain Agreements
All Principal Investigators ARE employed by the organization sponsoring the study.
Results Point of Contact
Layout table for Results Point of Contact information
Name/Title: Dr. Sam Schulman
Organization: McMaster University
Phone: 19055270271 ext 44810
EMail: schulms@mcmaster.ca
Layout table for additonal information
Responsible Party: Sam Schulman, McMaster University
ClinicalTrials.gov Identifier: NCT00356759     History of Changes
Other Study ID Numbers: PSI-06-21
First Submitted: July 24, 2006
First Posted: July 26, 2006
Results First Submitted: March 18, 2014
Results First Posted: August 22, 2018
Last Update Posted: August 22, 2018