Understanding USCDI, and How It Works With FHIR

USCDI elements are the basic data points that all modern health IT systems are expected to support.

What even is electronic health information? That’s not us talking - that’s the ONC, the federal head honchos of interoperability. ONC’s answer was the USCDI standard (formally called the United States Core Data for Interoperability, if you’re feeling fancy). 

USCDI is a standardized set of data elements, like patient names and medication lists, that are routinely shared without much effort. It’s the baseline standard for what different health tech tools and data formats generally have to support.

Currently, the USCDI helps regulators determine whether a healthcare provider is engaged in information blocking. In the US, all certified electronic health record (EHR) systems must share data that maps to the USCDI v1 elements.

Key USCDI Terms

The USCDI is a government-standardized set of data elements to facilitate healthcare information exchange. In USCDI:

  • Data elements are the most granular level at which a piece of data is exchanged.
  • Data classes are a grouping of related data elements.
  • Versions are updates to the USCDI standard.
    • as of writing, USCDI v2 is the most recent standard, and v3 is under review.
  • Levels denote the importance of certain data elements.
    • the current USCDI levels are Comment (least important), 1, and 2 (most important).

What Is USCDI?

Essentially, the USCDI elements are the basic healthcare data points that all modern healthcare systems and APIs are expected to support. 

The guiding USCDI principles, as set out by ONC, are to:

  1. Comprise a core set of structured and unstructured data needed to support patient care and facilitate patient access using health IT.
  2. Establish a consistent baseline of harmonized data elements that can be broadly reused across use cases, including those outside of patient care and patient access.
  3. Expand over time via predictable, transparent, and collaborative processes, weighing both anticipated benefits and industry-wide impacts.

USCDI are the data points which anti-info blocking requirements instruct IT vendors to share, starting from the effective date of April 5, 2021. In the future, USCDI elements may also inform the design of healthcare measurements and technology. Notably, ONC states that the USCDI “is intended to grow over time as standards mature and users’ needs evolve.”

USCDI elements - the full list of which are available at the ONC’s website - comprise many types of healthcare information about patients. Standard biographical data like “First Name” is a USCDI element, and so is vital medical information like “Pulse Oximetry”.

For example, an Immunization Record as standardized by USCDI does need to be exportable by an EHR. But more heterogeneous data like ophthalmologic pressure is not currently a USCDI element, and so does not yet need to be passed in a machine-readable format.

USCDI stems from the Cures Act, which set broad healthcare mandates. In the interoperability space, the wide-ranging Cures Act is known for its Anti-Information Blocking Rule, which facilitates and requires the sharing of healthcare data.

ONC was required to develop USCDI as a result of a Cures Act mandate to settle on an API that would be used to exchange electronic health information. While the FHIR format was ONC’s choice for an API, the Cures Act did not define what electronic health information was. ONC concluded that it could not fulfill its mandate without developing USCDI, which allowed healthcare developers to phase in the API-based exchange of healthcare data by initially limiting its exchange to USCDI elements.

The USCDI standard is intended to replace the Common Clinical Data Set (CCDS), a similar set of standards used during the 2010s.

How Particle Works With USCDI

Particle’s API finds and makes available patient records to our users. Particle provides USCDI elements in JSON payloads under FHIR when those elements are available (as we rely on the medical facilities in our network to comply with USCDI). Our API is compatible with all the USCDI elements that are in the records that we receive.

Parsing out USCDI elements is particularly helpful when working with FHIR, which supports atomic data sharing. Fully-integrated Particle customers using FHIR can query their patients’ records, continuously and automatically, for the USCDI elements that they choose. Users that query for C-CDA data instead will be able to find USCDI elements when they pull and parse individual files on their own.

Engineers can get a more complete look at how our API works with healthcare data by signing up for a free developer portal account.

What’s the Difference Between USCDI and HL7?

USCDI generally aligns with the FHIR and C-CDA formats - both of which are HL7 standards - when possible. The USCDI data classes are intentionally similar to those of FHIR and C-CDA. For instance, the draft USCDI standard dropped a data class to better match the HL7 formats.

ONC also judges potential additions to USCDI based on their current use and difficulty of implementation, explicitly advantaging elements that are already included in FHIR and C-CDA. HL7 formats, which were developed in consultation with ONC, have the advantage of being widely tested and well defined.

How You Can Shape USCDI

ONC will finalize USCDI v3 in July 2022. For this round of changes, ONC is prioritizing the addition of health equity measures. The v3 draft introduces elements like Patient Goals.

ONC also announced a related initiative, USCDI+, in October 2021. It’s a project where ONC reaches out to federal agencies, like CMS and the CDC, to make sure that their priorities have standardized reporting measures (although it’s not yet clear if these will be part of the main USCDI standard).

Many nonprofits, trade associations, and experts have weighed in on USCDI. You can too! ONC accepts elements and comments throughout the year.

The v3 submission process ended in September 2021, but USCDI is sticking to an annual feedback cycle. The comment process for USCDI v3 continues until April 30, 2022.