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Measure Specification


The National Library of Medicine (NLM) produces RxNorm. As described by the NLM, RxNorm is a normalized naming system for generic and branded drugs and is a tool for supporting semantic interoperation between drug terminologies and pharmacy knowledgebase systems. The United States Core Data for Interoperability (USCDI) recommends RxNorm for use with medications and substances (medications) associated with allergies and intolerances. USCDI v1 is a standard in the ONC Cure Act Final Rule.

Purpose of RxNorm

Hospitals, pharmacies, and other organizations use computer systems to record and process drug information. Because these systems use many different sets of drug names, it can be difficult for one system to communicate with another. To address this challenge, RxNorm provides normalized names and unique identifiers for medicines and drugs. The goal of RxNorm is to allow computer systems to communicate drug-related information efficiently and unambiguously.

Scope of RxNorm

RxNorm contains the names of prescription and many over-the-counter drugs available in the United States. RxNorm includes generic and branded drugs such as

  • Clinical drugs, which are pharmaceutical products given to (or taken by) a patient with therapeutic or diagnostic intent.
  • Drug packs, which are packs that contain multiple drugs, or drugs designed for administration in a specified sequence.

As noted on the RxNorm Overview page, radiopharmaceuticals, bulk powders, contrast media, food, dietary supplements, and medical devices such as bandages and crutches are generally out of scope for RxNorm.

RxNorm Term Types

RxNorm characterizes each concept in the code system as having a specific term type (TTY). TTYs are semantic tags that describe the type of information the concept conveys. An appendix of the RxNorm Technical Documentation provides a list of all RxNorm TTYs. Subsequent sections of this page provide recommendations for specific TTYs when building value sets for specific uses.

RxNorm Use in Quality Measures

RxNorm is the recommended national standard for medication vocabulary for clinical drugs and drug delivery devices. The intent is for RxNorm to cover all prescription medications approved for human use in the U.S. Measure developers should use RxNorm to reference a medication for administration, order, and dispensing. Measure developers should also use RxNorm to represent the object (i.e., the causative agent) of an allergy, adverse reaction, or intolerance due to a drug.

Because every drug information system commercially available today follows somewhat different naming conventions, there is a need for a standardized nomenclature for the smooth exchange of information. The goal of RxNorm is to allow various systems using different drug nomenclatures to share data efficiently at the appropriate level of abstraction. Each RxNorm clinical drug name reflects the active ingredients, strengths, and dose form comprising that drug. When any of these elements vary, creation of a new RxNorm drug name occurs as a separate concept.

The Blueprint content is the broadest interpretation of the RxNorm TTYs with which a measure developer could align, but some electronic clinical quality measure (eCQM) releases include value sets that focus on the minimum RxNorm identifiers needed for all general representations of the necessary drugs. While the Blueprint content includes branded TTYs in the guidance, authoring guidance has encouraged measure developers not to include branded term types because changes in branded identifiers for any single general drug (such as a Semantic Clinical Drug [SCD]) occur throughout the year and, even with the inclusion of value set addendum releases, there can be value sets that are out of sync with some implementer system content. Also, it provides for impartiality reducing the perception of branded drug favoritism. Given that RxNorm application content (and all drug information vendor products) can be used to map from the more stable general identifier to a branded identifier, and from other code systems such as National Drug Code (NDC) or proprietary code systems, the branded RxNorm TTYs were often not included under the assumption that if an implementer had a different identifier, the implementer could map to the included SCD RXCUI or generic pack (GPCK) RXCUI or any other TTY and ID according to the intention.

Find more information at the RxNorm website.

RxNorm and Allergy Value Sets

Allergy/intolerance value sets, when drawn from RxNorm, should include only the IN (ingredient) or PIN (precise ingredient) TTY. Measure developers should also review the guidance provided in the SNOMED CT section and on the Electronic Clinical Quality Improvement (eCQI) Resource Center.

Measure Developer Guidance

  • Always consider including a measure expression that appropriately removes a patient from a numerator or denominator population when there is an expectation that the patient should have received a substance, but the patient has an allergy/intolerance to the expected substance.
  • If there is an allergy/intolerance value set and a patient has an allergy/intolerance to any one of the substances, that will likely remove the patient from consideration for any substance in that value set.
  • When needing an allergy/intolerance value set to discriminate between the individual active ingredients in compound medications, it may be reasonable to identify the individual active ingredients for those medications included in the value sets used for expected therapies and then create the allergy/intolerance value set using that list of ingredients.
  • The allergy/intolerance value sets only indicate the substance/agent considered as the cause of the reaction. Do not use RxNorm or CVX to indicate the reaction.
  • The naming convention for value sets used for allergy/intolerance is to end the value set name with the word allergen, (e.g., Antithrombotic Therapy Allergen and Beta Blocker Therapy Allergen).
RxNorm and Medication Value Sets

Medication value sets, when used to represent administered, ordered, or recommended substances, must draw from RxNorm and include RxNorm concepts having TTYs

  • GPCK
  • SCD

CMS prefers that value sets used to represent acceptable medications will only include the RxNorm TTYs. This preference is because measure developers can map any other drug representation to one of these using the RxNorm content and applications, which means that value sets should have any formulation that is appropriate for use. The expectation is for implementers to map content found in some electronic health records to the most appropriate concept in the value set, preferably the concept with either a SCD or GPCK TTY.

However, when a measure requires identification of a single ingredient pharmacy-mixed admixture product with a strength not available as a RxNorm SCD, the measure developer may use the Semantic Clinical Dose Form Group (SCDG) term type for the ingredient as a direct reference code.

Measure developers may have some confusion between the use of dose formulation (strength) vs dose administration. For example, an antithrombotic value set did not contain all applicable RxNorm codes because some RxNorm codes represented nontherapeutic strengths for antithrombotic therapy if given as a single dose administration.

Therefore, when RxNorm codes exist to represent a strength potentially used to indicate a therapeutic dose, the measure developer should include all RxNorm codes representing those strengths in the value set. The value set purpose statement should include language to indicate intent using inclusion and exclusion criteria.

Example Inclusion criteria: “Includes concepts that represent medications to reach a therapeutic dose for anti-coagulation.”

See the eCQI Resource Center for more information on value sets.

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