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)

• 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)

• 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)

• Date and time stamp – required• Serial # - required• Device type / model - supplemental• Manufacturer - supplemental• User Identifier – supplemental

Following may be included in Status of Measurement• INR value out of therapeutic range – required*• INR value at dangerous clinical level – required*• INR value out of clinical range – required*

Data Objects(defines the objects needed to satisfy the data requirements

grouped and ordered logically)Clinical Data• Prothrombin Time (PT) - supplemental• Quick Value – supplemental• INR – required• Batch/code number – required• International Sensitivity Index (ISI) – supplemental• Status of measurement – required*

Monitoring• Target therapeutic range – required

Management• Medication – supplemental• Review period - supplemental• Recommended new level of medication – supplemental• Additional information – supplemental

Device• Device alarm conditions – required

Data Objects

Name Prothrombin Time (PT) Status May be provided Type Numeric Unit Seconds Additional attributes

Status of measurement

Description 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).

Name Quick value Status May be provided Type Numeric Unit Percentage Additional attributes

Status of measurement

Description 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 International Normalised Ratio (INR) Status Shall be provided in all INR monitors and mandatory in standard INR Type Numeric Unit INR (although this value has no units, it is a ratio, it is usual to express

INR results with INR as the unit) Additional attributes

Status of measurement

Description 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 Batch/code number Status Type Numeric Unit No units Additional attributes

Description This may record information from a strip regards batch number or similar information.

Name International Sensitivity Index (ISI) Status May be provided Type Numeric Unit No units Additional attributes

Status of measurement

Description 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 of measurement Status Mandatory in standard device Type Enumeration Unit Additional attributes

Description 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 Target therapeutic range Status Mandatory in standard device Type Numeric Unit No units Additional attributes

Description 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 Current Medication Schedule Status Optional Type Schedule Unit Drug:dose e.g. warfarin:mg Additional attributes

Description 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).

Name Current Average Medication Level Status Optional Type Numeric Unit Drug:dose e.g. warfarin:mg Additional attributes

Description 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 Recommended new medication schedule Status Must be provided if device provides advice on new level of medication Type Schedule Unit Drug:dose e.g. warfarin:mg Additional attributes

Description 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).

Name Recommended new level of medication Status Must be provided if device provides advice on new level of medication Type Numeric Unit Drug:dose e.g. warfarin:mg Additional attributes

Description 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 Review Period Status Optional Type Time Unit Additional attributes

Description 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.

Name Additional Information Status Optional Type ? Unit Additional attributes

Description 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 Device alarm conditions Status Mandatory Type Alarm – enumeration Unit Additional attributes

Status of measurement

Description 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 Persistent metric store Status Type Unit Additional attributes

INR Status of measurement Batch/code number Current medication Target level Recommended new medication

Description 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

References1.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

Object PHD-I NR object instances

1

1..1

MDS I NR

0..1

0..1

0..1

0..1 Schedule Current m edication schedule

1..1

1..1

1..1

1..1

0..1

0..1

0..1

0..1

0..1

Numeric Current m edication level

Schedule New m edication schedule

Numeric New m edication level

Numeric Review period

? Additional inform ation

Numeric Prothrom bin tim e

Numeric I NR

Numeric Batch code

Numeric I SI

Enumeration Measurem ent status

Enumeration Device alarm

Numeric Target therapeutic range

Numeric Quick value