Experts , however , have commented that there may be under-utilization of OAT due to patient factors , physician factors , or regional practice variations and that sub-optimal patient management may also occur .
These models are not suitable for all patients and require the identification and education of suitable c and i date s. Potential advantages of POC devices include improved convenience to patients , better treatment compliance and satisfaction , more frequent monitoring and fewer thromboembolic and hemorrhagic complications .
Potential disadvantages of the device include the tendency to underestimate high INR values and overestimate low INR values , low thromboplastin sensitivity , inability to calculate a mean normal PT , and errors in INR determination in patients with antiphospholipid antibodies with certain instruments .
Although treatment satisfaction and quality of life ( QoL ) may improve with POC INR monitoring , some patients may experience increased anxiety or preoccupation with their disease with these strategies .
The majority of studies reported favourable impacts of POC INR monitoring on QoL and found better treatment satisfaction with POC monitoring .
UNLABELLED SUBJECT OF THE EVIDENCE -BASED ANALYSIS : The purpose of this evidence based analysis report is to examine the safety and effectiveness of point-of-care ( POC ) international normalized ratio ( INR ) monitoring devices for patients on long-term oral anticoagulation therapy ( OAT ) .
CLINICAL NEED TARGET POPULATION AND CONDITION Long-term OAT is typically required by patients with mechanical heart valves , chronic atrial fibrillation , venous thromboembolism , myocardial infa rct ion , stroke , and /or peripheral arterial occlusion .
It is estimated that approximately 1 % of the population receives anticoagulation treatment and , by applying this value to Ontario , there are an estimated 132,000 patients on OAT in the province , a figure that is expected to increase with the aging population .
Patients on OAT  are regularly monitored and their medications adjusted to ensure that their INR scores remain in the therapeutic range .
This can be challenging due to the narrow therapeutic window of warfarin and variation in individual responses .
Optimal INR scores depend on the underlying indication for treatment and patient level characteristics , but for most patients the therapeutic range is an INR score of between 2.0 and 3.0 .
There is currently no population -based Ontario data to permit the assessment of patient care , but recent systematic review s have estimated that less that 50 % of patients receive OAT on a routine basis and that patients are in the therapeutic range only 64 % of the time .
OVERVIEW OF POC INR DEVICES POC INR devices offer an alternative to laboratory-based testing and venipuncture , enabling INR determination from a fingerstick sample of whole blood .
Independent evaluations have shown POC devices to have an acceptable level of precision .
They permit INR results to be determined immediately , allowing for more rapid medication adjustments .
POC devices can be used in a variety of setting s including physician offices , ACCs , long-term care facilities , pharmacies , or by the patients themselves through self-testing ( PST ) or self-management ( PSM ) techniques .
With PST , patients measure their INR values and then contact their physician for instructions on dose adjustment , whereas with PSM , patients adjust the medication themselves based on pre-set algorithms .
EffectivenessDoes POC INR monitoring improve clinical outcomes in various setting s compared to st and ard laboratory-based testing?Does POC INR monitoring impact patient satisfaction , QoL , compliance , acceptability , convenience compared to st and ard laboratory-based INR determination ?
Cost-effectivenessWhat is the cost-effectiveness of POC INR monitoring devices in various setting s compared to st and ard laboratory-based INR determination ?
ANTICOAGULATION CONTROL Anticoagulation control is measured by the percentage of time INR is within the therapeutic range or by the percentage of INR values in the therapeutic range .
An analysis of the lowest effective intensity of prophylactic anticoagulation for patients with nonrheumatic atrial fibrillation.
BACKGROUND To avert major hemorrhage , physicians need to know the lowest intensity of anticoagulation that is effective in preventing stroke in patients with atrial fibrillation . Since the low rate of stroke has made it difficult to perform prospect i ve studies to resolve this issue , we conducted a case-control study . METHODS We studied 74 consecutive patients with atrial fibrillation who were admitted to our hospital from 1989 through 1994 after having an ischemic stroke while taking warfarin .  For each patient with stroke , three controls with nonrheumatic atrial fibrillation who were treated as out patients were r and omly selected from the 1994 registry of the anticoagulant-therapy unit ( 222 controls ) . We used the  international normalized ratio ( INR )  to measure the intensity of anticoagulation .  For the patients with stroke , we used INR at admission ; for the controls , we selected the INR that was measured closest to the month and day of the matched case patient 's hospital admission . RESULTS The risk of stroke rose steeply at INRs below 2.0 . At an INR of 1.7 , the adjusted odds ratio for stroke , as compared with the risk at an INR of 2.0 , was 2.0 ( 95 percent confidence interval , 1.6 to 2.4 ) ; at an INR of 1.5 , it was 3.3 ( 95 percent confidence interval , 2.4 to 4.6 ) ; and at an INR of 1.3 , it was 6.0 ( 95 percent confidence interval , 3.6 to 9.8 ) . Other independent risk factors were previous stroke ( odds ratio , 10.4 ; 95 percent confidence interval , 4.4 to 24.5 ) , diabetes mellitus ( odds ratio , 2.95 ; 95 percent confidence interval , 1.3 to 6.5 ) , hypertension ( odds ratio , 2.5 ; 95 percent confidence interval , 1.1 to 5.7 ) , and current smoking ( odds ratio , 5.7 ; 95 percent confidence interval , 1.4 to 24.0 ) . CONCLUSIONS Among patients with atrial fibrillation , anticoagulant prophylaxis is effective at INRs of 2.0 or greater . Since previous studies have indicated that the risk of hemorrhage rises rapidly at INRs greater than 4.0 to 5.0 , tight control of anticoagulant therapy to maintain the INR between 2.0 and 3.0 is a better strategy than targeting lower , less effective levels of anticoagulation
Experts , however , have commented that there may be under-utilization of OAT due to patient factors , physician factors , or regional practice variations and that sub-optimal patient management may also occur .
These models are not suitable for all patients and require the identification and education of suitable c and i date s. Potential advantages of POC devices include improved convenience to patients , better treatment compliance and satisfaction , more frequent monitoring and fewer thromboembolic and hemorrhagic complications .
Potential disadvantages of the device include the tendency to underestimate high INR values and overestimate low INR values , low thromboplastin sensitivity , inability to calculate a mean normal PT , and errors in INR determination in patients with antiphospholipid antibodies with certain instruments .
Although treatment satisfaction and quality of life ( QoL ) may improve with POC INR monitoring , some patients may experience increased anxiety or preoccupation with their disease with these strategies .
The majority of studies reported favourable impacts of POC INR monitoring on QoL and found better treatment satisfaction with POC monitoring .
UNLABELLED SUBJECT OF THE EVIDENCE -BASED ANALYSIS : The purpose of this evidence based analysis report is to examine the safety and effectiveness of point-of-care ( POC ) international normalized ratio ( INR ) monitoring devices for patients on long-term oral anticoagulation therapy ( OAT ) .
CLINICAL NEED TARGET POPULATION AND CONDITION Long-term OAT is typically required by patients with mechanical heart valves , chronic atrial fibrillation , venous thromboembolism , myocardial infa rct ion , stroke , and /or peripheral arterial occlusion .
It is estimated that approximately 1 % of the population receives anticoagulation treatment and , by applying this value to Ontario , there are an estimated 132,000 patients on OAT in the province , a figure that is expected to increase with the aging population .
Patients on OAT  are regularly monitored and their medications adjusted to ensure that their INR scores remain in the therapeutic range .
This can be challenging due to the narrow therapeutic window of warfarin and variation in individual responses .
Optimal INR scores depend on the underlying indication for treatment and patient level characteristics , but for most patients the therapeutic range is an INR score of between 2.0 and 3.0 .
There is currently no population -based Ontario data to permit the assessment of patient care , but recent systematic review s have estimated that less that 50 % of patients receive OAT on a routine basis and that patients are in the therapeutic range only 64 % of the time .
OVERVIEW OF POC INR DEVICES POC INR devices offer an alternative to laboratory-based testing and venipuncture , enabling INR determination from a fingerstick sample of whole blood .
Independent evaluations have shown POC devices to have an acceptable level of precision .
They permit INR results to be determined immediately , allowing for more rapid medication adjustments .
POC devices can be used in a variety of setting s including physician offices , ACCs , long-term care facilities , pharmacies , or by the patients themselves through self-testing ( PST ) or self-management ( PSM ) techniques .
With PST , patients measure their INR values and then contact their physician for instructions on dose adjustment , whereas with PSM , patients adjust the medication themselves based on pre-set algorithms .
EffectivenessDoes POC INR monitoring improve clinical outcomes in various setting s compared to st and ard laboratory-based testing?Does POC INR monitoring impact patient satisfaction , QoL , compliance , acceptability , convenience compared to st and ard laboratory-based INR determination ?
Cost-effectivenessWhat is the cost-effectiveness of POC INR monitoring devices in various setting s compared to st and ard laboratory-based INR determination ?
ANTICOAGULATION CONTROL Anticoagulation control is measured by the percentage of time INR is within the therapeutic range or by the percentage of INR values in the therapeutic range .