PrescribeIT® Specification and Guide Version 5.0

A measured or counted amount of a medication expressed as a value and human-readable string with optional coded units expressed in a local coding system

Usage Note: Quantity is used throughout the messages. It may be a drug form (e.g. TAB) an administrable drug (e.g. PUFF) form or a unit of measure (e.g. mg).

unique id for the element within a resource (for internal references).

May be used to represent additional information that is not part of the basic definition of the element. In order to make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

The value of the measured amount. The value includes an implicit precision in the presentation of the value.

Precision is handled implicitly in almost all cases of measurement.

The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).

Not allowed to be used in this context

Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.

This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.

A human-readable form of the unit.

There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.

The identification of the system that provides the coded form of the unit.

Need to know the system that defines the coded form of the unit.

A computer processable form of the unit in some unit representation system.

Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.

Conformance Rule: A Code must be supplied if one is available from the PrescriptionDoseQuantityUnit subset. If the user picks a prescribed quantity unit that does not have a code in the PrescriptionDoseQuantityUnit subset, only then can unit be supplied without a code. If a receiving system receives a code that it doesn't recognize, the system must just display the unit.