Health Services Research

The Common Data Model

The PCORnet Common Data Model (CDM) is a method of organizing data into a standard structure to enhance its usability for research. The CDM, along with REACHnet’s Global Patient Identification (GPID) system, enable the creation of a single health record for each patient composed of records from any partner health systems where the patient received care.

REACHnet’s partner health systems map patient data from their electronic health records to CDM specifications and transfer the data to REACHnet’s datacenter. Previously, a research query to find patients meeting certain clinical criteria would have to be re-written at each institution to reflect the design of their electronic medical record system. Not only is this time consuming, but it also increases the chance for errors. Using the CDM, however, a query can be run at all sites, and all results will be in the same format. This design facilitates interoperability, expedites the research process, and reduces duplication of effort.

The CDM is a limited dataset, which means that the only Protected Health Information (PHI) elements are dates, such as birth dates, encounter dates, procedure dates, among others. The composition of the CDM as a limited dataset eliminates many of the risks associated with PHI, as names, social security numbers, addresses, and other elements that are inherently identifiable are absent. However, the lack of identifiers makes it difficult to match patient records across health systems to create deduplicated, longitudinal records. To solve that challenge, REACHnet implemented a Global Patient Identification (GPID) hashing and matching algorithm that links patient records without sharing identifiable information.