Consolidated CDA R2.1 DSTU Update

The purpose of this project is to quickly develop an update to the existing Consolidated CDA DSTU 2.0 specification to support compatibility with C-CDA 1.1. The requirements are that an existing EHR certified under 2014 or 2015 ONC Standards and Certification criteria be able to correctly interpret the content of a C-CDA 2.1 without requiring change to the product presuming that it has followed good development practices in interpretation of the CDA Standards and C-CDA 1.1 specifications.

The project builds on the work of the Dual-CDA Compatible Task Force to address the issues it found between C-CDA Release 1.1 and C-CDA Release 2.0.

Google Drive with work products Google Sheet for IGs dependent on C-CDA R2.1

Approved Compatibility Principles

HL7 will apply these compatibility principles against templates present in C-CDA R1.1 and C-CDA R2.0. The baseline for C-CDA R2.1 is C-CDA R2.0:

1. When a SHALL constraint present in C-CDA Release 1.1 is relaxed to SHOULD or MAY in C-CDA Release 2.0, the C-CDA Release 2.1 specification will increase the strength of that constraint to SHALL when compatibility is asserted.
2. When a SHALL constraint present is C-CDA Release 1.1. is removed in C-CDA Release 2.0, the C-CDA 2.1 specification will add that constraint when supporting compatibility.
3. When a SHOULD or MAY constraint present in C-CDA Release 1.1 is relaxed or removed in C-CDA Release 2.0, the C-CDA Release 2.1 specification will remain silent. As these constraints are not strictly required in a C-CDA 1.1 instance, they are not necessary for backwards compatibility. Implementers who wish to continue to convey data elements found in C-CDA 1.1. with a SHOULD or MAY constraint can still report this information as it was done in C-CDA 1.1 so long as these are also conformant with this specification [Are there any cases where we need to worry about this? Will see if anyone comes up with others by Thursday.]
4. A SHALL, SHOULD or MAY constraint added in C-CDA R2.0 that is not explicitly prohibited in C-CDA R1.1 will be added to C-CDA R2.1.
5. When a vocabulary or value set binding has changed for an element to a new coding system in C-CDA Release 2.0, C-CDA Release 2.1 will, when supporting backwards compatibility; require the use of the old value set or vocabulary in element/code, and the new value set or vocabulary in element/translation, and otherwise require the use of the new value set or vocabulary in code as it was constrained (with the same strength appearing) in C-CDA 2.0.

C-CDA R2.1 Compatibility Modes

1. C-CDA R2.1 only supports compatibility mode
2. C-CDA R2.1 supports compatibility mode and ability to send requirements as specified in C-CDA R2.0

With either option, C-CDA R2.1 will include all of the new templates from C-CDA R2.0

Implementation guidelines

1. If you assert compatibility at the document level then compatibility templates, where available, will be used throughout the entire document instance.
2. New templates in C-CDA R2.0 that were not in C-CDA R1.1 are allowed in a C-CDA R2.1 instances.
3. New templates in C-CDA R2.0 that were not in C-CDA R1.1 are not being evaluated for compatibility.