Transcript N0256_INR-presentation_WG7_meeting_2009-01

11073-10418 INR
Purpose
• Monitor the coagulation of blood for those on anti-coagulation therapy
• Monitor for therapeutic levels of medication
• Monitor for safe levels of therapy
• Advise on adjustment to therapy
• Titrate to therapeutic level
Approach
• Coagulability measured from sample of arterial or venous blood using
thromboplastin to determine prothrombin time (PT)
• Different thromboplastins available and will give different results
INR - International Normalized Ratio
• Determines coagulation time compared to normalized reference
• Allows values from different thromboplastins to be compared
• Given as a simple number
Use Cases
Health care professional testing and therapy management
• Regular measurement to maintain therapeutic level by a health care
professional
• Management by the health care professional
Self testing
• Regular measurement to maintain therapeutic level by the patient
• Measurements sent to health care professional for advice
• Warnings if out of therapeutic range or if severely out of range
Self management
• Regular measurement to maintain therapeutic level by the patient
• Patient advised how to self manage
• Device may have target level, information on drug and dose and
intelligence to advise on medication change
Use Cases
Patient Care Pathway
• Patient is under medical care of primary “physician” (will vary by country
and system) who has responsibility for regime
• Measurements reviewed and advice may be given to alter medication
• Warnings if out of therapeutic range and medical intervention required
• Warnings if severely out of range
Data Requirements
(this defines the data that the INR must provide in some way)
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INR - required
Date and time stamp - required
Target therapeutic range – required
INR value out of therapeutic range – required
INR value at dangerous clinical level – required
INR value out of clinical range – required
Status of measurement – required
Batch/code number – required
Device alarm conditions - required
Serial # - required
Prothrombin Time (PT) - supplemental
Quick Value – supplemental
International Sensitivity Index (ISI) – supplemental
Medication – supplemental
Review period - supplemental
Recommended new level of medication – supplemental
Device type / model - supplemental
Manufacturer - supplemental
User Identifier – supplemental
Additional information - supplemental
Data Objects
(defines the objects needed to satisfy the data requirements)
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INR – required
Target therapeutic range – required
INR value out of therapeutic range – required
INR value at dangerous clinical level – required
INR value out of clinical range – required
Batch/code number – required
Status of measurement - required
Device alarm conditions – required
Prothrombin Time (PT) - supplemental
Quick Value – supplemental
International Sensitivity Index (ISI) – supplemental
Medication – supplemental
Review period - supplemental
Recommended new level of medication – supplemental
Additional information - supplemental
Data Attributes
(specifies data that already is defined as an attribute or otherwise)
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Date and time stamp – required
Serial # - required
Device type / model - supplemental
Manufacturer - supplemental
User Identifier – supplemental
Following may be included in Status of Measurement
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INR value out of therapeutic range – required*
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INR value at dangerous clinical level – required*
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INR value out of clinical range – required*
Data Objects
(defines the objects needed to satisfy the data requirements
grouped and ordered logically)
Clinical Data
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Prothrombin Time (PT) - supplemental
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Quick Value – supplemental
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INR – required
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Batch/code number – required
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International Sensitivity Index (ISI) – supplemental
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Status of measurement – required*
Monitoring
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Target therapeutic range – required
Management
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Medication – supplemental
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Review period - supplemental
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Recommended new level of medication – supplemental
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Additional information – supplemental
Device
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Device alarm conditions – required
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Prothrombin Time (PT)
May be provided
Numeric
Seconds
Status of measurement
Name
Status
Type
Unit
Additional
attributes
Description
Quick value
May be provided
Numeric
Percentage
Status of measurement
Either venous or capillary blood can be used to monitor
anticoagulation therapy. To produce a reading, thromboplastin is
added to the blood to activate coagulation. This causes a blood clot to
form. The time it takes for this clot to form is measured in seconds and
is known as the prothrombin time (PT).
In some European countries, blood coagulability was typically
expressed in a unit known as the Quick value. In this case the
measured prothrombin time is expressed in relation to the coagulation
time of a healthy person. The value obtained is the "percentage of the
standard value". In a person not receiving oral anticoagulation the
"normal" Quick value is between 80 and 120%. A Quick value of only
30%, for instance, indicates that the blood coagulation time is longer
than normal. The longer the patient's coagulation time, the lower the
Quick value.
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
International Normalised Ratio (INR)
Shall be provided in all INR monitors and mandatory in standard INR
Numeric
INR (although this value has no units, it is a ratio, it is usual to express
INR results with INR as the unit)
Status of measurement
As the Quick/PT value is very country- and laboratory- dependent,
nowadays the value mostly measured is the INR value. It is the
globally recommended unit for measuring thromboplastin time. INR
makes coagulation measurements extensively comparable despite the
numbers of different thromboplastins used.
INR = (Patient's PT / Normal mean PT) ISI
For example: The PT of a patient receiving oral anticoagulant is 64
seconds (= 18% Quick). The prothrombin time of a normal plasma is
22 seconds (= 100% Quick). The ISI of the thromboplastin used is
0.93. Substituting this value in the formula above gives the following
INR:
(64) / (22) 0.93 = 2.7 INR
This signifies a coagulation time that is 2.7 times longer than the
standard. The longer the patient's coagulation time, the higher the INR.
Initially, the tests are frequently needed, as - depending on the patient the adjustment requires some time. Travelling to the healthcare
professional or laboratory means time off for active people, less
independence and a disruption of daily routine. Later, when the patient
is properly adjusted and stabilized, PT/INR monitoring is commonly
done at intervals of three to four weeks.
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Batch/code number
Name
Status
Type
Unit
Additional
attributes
Description
International Sensitivity Index (ISI)
May be provided
Numeric
No units
Status of measurement
Numeric
No units
This may record information from a strip regards batch number or
similar information.
Quick values measured with different thromboplastins cannot be
directly compared with one another. To render coagulation times as
comparable as possible, in 1983 the World Health Organization
(WHO) approved a standard thromboplastin. Every manufacturer of
thromboplastin must calibrate it against the WHO standard (2
references exist: one for human recombinant based thromboplastins,
one for rabbit brain based ones). The value obtained is known as the
International Sensitivity Index (ISI). This enables the various
sensitivities of the thromboplastins to be ascertained.
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Status of measurement
Mandatory in standard device
Enumeration
This provides extra information on a measurement, specifically if the
measurement is invalid due to a problem in the measurement test strip
or reagent. Factors include:
Out of date
Excess temperature
Excess humidity
Excess light
Excess problem (cause indeterminate)
Other damage
Insufficient blood
Test strip/reagent not valid for device
Test incomplete
Out of clinical range, too high
Out of clinical range, too low
Dangerous too high
Dangerous too low
Therapeutic too high
Therapeutic too low
*Calibration measurement (could be included in status of numeric)
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Target therapeutic range
Mandatory in standard device
Numeric
No units
This provides the target therapeutic range for the patient. It is user
defined. This value is used to determine alarm conditions and in
algorithms to determine recommended new level of medication.
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Current Medication Schedule
Optional
Schedule
Drug:dose e.g. warfarin:mg
Name
Status
Type
Unit
Additional
attributes
Description
Current Average Medication Level
Optional
Numeric
Drug:dose e.g. warfarin:mg
This allows the patient to record into the device the current level of
their anti coagulation medication so that a physician may assess the
success of the therapeutic level. This object may specify the
medication as a schedule, allowing for variation of daily dose (e.g.
over a week).
This shows the current level of anti coagulation medication as an
average value determined from the schedule so that a physician may
assess the success of the therapeutic level. This is the value typically
used by software systems to determine a new level of medication.
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Recommended new medication schedule
Must be provided if device provides advice on new level of medication
Schedule
Drug:dose e.g. warfarin:mg
Name
Status
Type
Unit
Additional
attributes
Description
Recommended new level of medication
Must be provided if device provides advice on new level of medication
Numeric
Drug:dose e.g. warfarin:mg
Devices capable of applying an algorithm to advise a patient on a new
medication schedule can record the recommended new medication
schedule. The new schedule will be based on associated INR
measurement and current level of medication and these must be
recorded in the same PM-Segment. Information on the algorithm may
be provided. This might be a text reference. This object may specify
the medication as a schedule, allowing for variation of daily dose (e.g.
over a week).
Devices capable of applying an algorithm to advise a patient on a new
level of medication can record the recommended new average level of
medication. The new level will be based on associated INR
measurement and current level of medication and these must be
recorded in the same PM-Segment. Information on the algorithm may
be provided. This might be a text reference.
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Review Period
Optional
Time
Name
Status
Type
Unit
Additional
attributes
Description
Additional Information
Optional
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This provides information on the time when medication should next be
reviewed. It can act as a reminder for the patient to take their next
measurement.
This provides information that is supplied by the patient to record
significant events, such as nose bleeds, change of other medication,
change of dietary habit, going on vacation
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Device alarm conditions
Mandatory
Alarm – enumeration
Status of measurement
This provides information on any device specific alarm conditions.
These include:
Battery low
Excess temperature
Excess humidity
Test strip/reagent not valid for device
Data Objects
Name
Status
Type
Unit
Additional
attributes
Description
Persistent metric store
INR
Status of measurement
Batch/code number
Current medication
Target level
Recommended new medication
Will store indefinitely last n measurements and associated information.
Number of measurements n is not defined but would normally be
sufficient to store all measurements between visits to physician.
This is typically 6 weeks and should allow 2 measurements per day.
100 is minimum recommended.
For each INR the above data is stored.
References
References
1.Lutze G. Useful facts about coagulation. Mannheim: Roche Diagnostics GmbH, 2000. (data on file)
2.Wagner C, Dati F. Thromboplastinzeit (german article). In: Thomas L, ed. Labor und Diagnose:
TH-Books Verlagsgesellschaft, 2000; 613-616.
1.Kovaks MJ et al. Thromb Haemost 1994; 71: 727-730.
Domain Information Model
O b je c t P H D - I N R o b je c t in s t a n c e s
MDS
IN R
1
P r o th r o m b in tim e
Q u ic k v a lu e
IN R
B a tc h c o d e
IS I
N u m e ric
N u m e ric
N u m e ric
N u m e ric
N u m e ric
0 ..1
0 ..1
S c h e d u le
C u r r e n t m e d ic a tio n s c h e d u le
0 ..1
N u m e ric
C u r r e n t m e d ic a tio n le v e l
0 ..1
S c h e d u le
N e w m e d ic a tio n s c h e d u le
0 ..1
1 ..1
1 ..1
0 ..1
N u m e ric
N e w m e d ic a tio n le v e l
0 ..1
0 ..1
R e v ie w p e r io d
E n u m e ra tio n
M e a s u r e m e n t s ta t u s
N u m e ric
1 ..1
0 ..1
A d d itio n a l in f o r m a tio n
E n u m e ra tio n
D e v ic e a la r m
N u m e ric
T a r g e t th e r a p e u t ic r a n g e
1 ..1
1 ..1
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