The eCQM Data Element Repository (DERep) is an online, searchable repository which provides all the data elements associated with eCQMs in CMS programs, as well as the definitions for each data element.

# Glossary

**Data Element Repository**

**Data element validity**

Data element validity is the extent to which the information represented by the data element or code used in the measure reflects the actual concept or event intended. See also measure validity. For example

- A medication code is used as a proxy for a diagnosis code
- Data element response categories include all values necessary to provide an accurate response

**Denominator**

The denominator is the lower part of a fraction used to calculate a rate, proportion, or ratio. It can be the same as the initial population or a subset of the initial population to further constrain the population for the purpose of the measure. Continuous variable measures do not have a denominator, but instead define a measure population.

**Denominator Exception**

A denominator exception is any condition that should remove a patient, procedure, or unit of measurement from the denominator of the performance rate only if the numerator criteria are not met. A denominator exception allows for adjustment of the calculated score for those providers with higher risk populations. A denominator exception also provides for the exercise of clinical judgment and should be specifically defined where capturing the information in a structured manner fits the clinical workflow. A denominator exception is used only in proportion measures. Denominator exception cases are removed from the denominator. However, the number of patients with valid exceptions may still be reported. Allowable reasons fall into three general categories - medical reasons, patient reasons, or system reasons.

**Denominator Exclusion**

A denominator exclusion is a case that should be removed from the measure population and denominator before determining if numerator criteria are met. Denominator exclusions are used in proportion and ratio measures to help narrow the denominator. For example, patients with bilateral lower extremity amputations would be listed as a denominator exclusion for a measure requiring foot exams.

**Direct Reference Code**

A direct reference code (DRC) is a specific code that is referenced directly in the eCQM logic to describe a data element or one of its attributes. Direct reference code metadata include the description of the code, the code system from which the code is derived, and the version of that code system.