Data Dictionary

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A Data Dictionary is a collection of all data elements present within the various systems within an organization and their associated metadata.[1] This metadata includes the various attributes that describe the element, its purpose, and any corresponding relationships to other elements.

Rationale for a Data Dictionary

Within most modern healthcare organizations exists a large collection of systems collecting and presenting data. Often, these systems do so using similar terms, but different meanings. This creates repositories of data that are disparate until the context of each element is understood. A data dictionary aims to create a central location to store and track all of these elements from each system within an organization. This allows for more meaningful understanding of relationships and a uniform set of definitions governing all systems within the organization.

Example A common example is shown by describing an organization utilizing different EHRs between clinical departments. In our example, an organization’s Emergency Department may utilize an EHR that utilized the World Health Organization’s definition of an adolescent as any person between the ages of 10 and 19.[2] If this same adolescent is subsequently admitted to the hospital under the care of the Pediatrics Department they may utilize a separate EHR that arbitrarily defines an adolescent as any person between nine and 17. In this scenario the term adolescent is not always representative of the same population. This may have implications in the organization’s data operations including government reporting, monitoring, and research.

Types of Data Dictionaries

Most data dictionaries fall within two broad categories. The first, a database management system (DBMS), is a tool used to document the actual database layer within a target system.3 This is often utilized by the information technology department in managing their database infrastructure. The second type of data dictionary is the organization-wide data dictionary.3 This dictionary aims to describe the common terms that might be utilized within all systems throughout an organization. Its main focus is to bring data integrity to an organization’s entire data set through documentation of standard definitions, formats, and use cases.

It is likely that most organizations would require creation of both available types to form a complete picture of their data and to further the organization’s data governance strategy.

Example Metadata

The metadata included within a data dictionary will depend on which type of data dictionary is being created and the use-case for the dictionary. A brief healthcare focused example might be to describe a single set of metadata used to capture a medication’s name. Database Management System Database | dbPharmacyData Table | dbo.MedicationNames Element Name | Medication Name Element ID | 132 Type | String Size | 32-bits Format | [a-z] Allow Null? | False Foreign Key(s) | dbo.MedicationDoses.NamesID Context | Used with dbo.MedicationNames.isGeneric to indicate if a particular name is Brand or Generic. Comment | Stores each medication’s name as a lowercase string.

Orgnaization-wide Data Dictionary Element Name | Generic Medication Name Type | String Minimum Size | 3 characters Maximum Size | 50 characters Format | lowercase letters (a-z) Example | omeprazole Usage | The generic medication name element is utilized to uniquely identify each medication’s official name as assigned by the United States Adopted Names Council (USAN). Associated Elements | Medication Brand Name, Medication Doses, Medication Routes, Medication Schedules Utilizing Systems | PharmacyApp, Adverse Event Reporting System

References

  1. S&I Framework Clinical Element Data Dictionary. http://wiki.siframework.org/S%26I+Framework+CEDD+Overview?system=mdr&title=SI+Clinical+Element+Data+Dictionary+WG&url=http%3A%2F%2Fwiki.siframework.org%2FS%2526I%2BFramework%2BCEDD%2BOverview
  2. Adolescent development. http://www.who.int/maternal_child_adolescent/topics/adolescence/dev/en/


Submitted by Nicholas Perkins