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October 2013

Two Systems, One Direction
By Selena Chavis
For The Record
Vol. 25 No. 14 P. 10

Serving different functions, ICD-10 and SNOMED CT nevertheless can work in tandem as a powerful duo.

As many federal initiatives begin to converge across the health care landscape, the role of industry standards to support the movement toward higher quality care delivery has heightened. The transition to the ICD-10-CM classification system represents one critical standard that the industry currently is navigating. Another is the deployment and adoption of the former Systematized Nomenclature of Medicine, now referred to as SNOMED Clinical Terms (SNOMED CT), to comply with meaningful use.

Industry professionals point out that while there is no direct relationship between these two systems, the potential for the pair to work together to impact care delivery is high. That’s why many experts suggest that health care organizations leverage the ICD-10-CM transition process as an opportunity to introduce SNOMED CT within their EHRs to lay the most effective foundation for future care delivery.

“It’s like killing two birds with one stone,” says Kin Wah Fung, MD, MS, MA, a staff scientist with the Lister Hill National Center for Biomedical Communications of the National Library of Medicine (NLM), adding that implementing the extensive clinical terminology foundation of SNOMED CT alongside the enhanced detail of the ICD-10 classification system provides a high-quality approach to addressing fast-approaching compliance deadlines. “By October of next year, people will need to move on to ICD-10. Most hospitals need a major overhaul of how information is captured in the EHR.”

Pointing to the significant difference in detail between ICD-9 and ICD-10, Fung says a simple forward mapping likely will not be sufficient for most health care providers to make a successful transition. It will require more complex mapping strategies that are best served by a common medical vocabulary such as SNOMED CT that can provide the level of clinical detail needed to support mapping as well as allow HIT systems to translate disparate terms.

“For health care systems to be interoperable and able to safely exchange data, uniform formats are required and medical terms must be used that are universally understood,” says Rita Scichilone, MHSA, RHIA, CCS, CCS-P, senior advisor of global standards for AHIMA. “Standardized clinical terminologies supply this part of the process, and SNOMED CT is the best candidate for general use. It’s a terminology, and it goes way beyond a disease process, such as what is covered by the International Classification of Diseases.”

Owned and maintained by the Denmark-based International Health Terminology Standards Development Organisation (IHTSDO), the SNOMED CT code set has a lineage dating back more than 40 years and a long track record of acceptance across the globe. Put in simple terms, the code set enables computers to understand medical language and act on it by drawing on the concepts and definitions found in many standard terminologies throughout the health care industry.

“A standard code set like SNOMED is a vital component for safe and accurate communication,” Fung explains. “It is much more suitable than what most organizations are using in their EHRs.”

The need for a common clinical language cannot be overstated when it comes to the industry’s move toward greater interoperability and exchange of information. The ability to capture information accurately and with the detail needed to effectively support clinical decision-support technology and point-of-care strategies requires that IT infrastructures understand the clinical and medical terminology being communicated. “SNOMED CT is designed for a large number of different applications,” Scichilone says. “It is very useful for clinical decision support, research, clinical trials, and other initiatives. There’s an array of interests for SNOMED CT for clinical use.”

Comprehensive may be the best way to describe the reach of the SNOMED CT code set. Encompassing more than 300,000 concepts, 779,000 descriptions, 19 hierarchies, and 1.5 million relationships, the system uses a string of numbers to represent a biomedical concept, which then is displayed in a format users can read. The concepts essentially are the computer-readable code, which the hierarchies organize into levels of granularity. The descriptions represent the accompanying words or phrases that become the human readable representations, while the relationships are used to link the concepts.

Subsets also are provided to help narrow and further define codes for a particular use. For example, the CORE Problem List Subset developed by the NLM identifies the codes most useful for documentation and encoding at a summary level, which can help with building problem lists, discharge diagnosis, and reasons for encounter. Other NLM subsets include a nursing problem list subset for use in care planning and the convergent medical terminology subsets donated by Kaiser Permanente that feature 75,000 clinician- and patient-friendly medical concepts linked to US and international interoperability standards.

Because it is a requirement for meeting stage 2 of meaningful use, SNOMED CT adoption has gained considerable traction. The federal regulations specify its use for documenting patient problems, encounter diagnosis, procedures, family health history, and smoking status.

Scichilone says the premise for adopting SNOMED CT as part of meaningful use is directly related to the need for more granularity in documenting patient problems. “The terminology is complementary to coding systems already in place, including ICD-10-CM and ICD-10-PCS,” she says. “The reason for the use of SNOMED CT in meaningful use is to enable clinical data capture, storage, and reuse, which will be understood and shareable for health information exchange and a variety of clinical data management and retrieval tasks.”

In the case of problem lists, the goal is to provide an accurate snapshot of issues and diagnoses as patients move from provider to provider through the health care continuum. EHRs historically and in their present form do not provide an efficient way to capture this information primarily because of interoperability issues and the lack of a standardized terminology.

To overcome this roadblock, many providers have relied on the ICD-9-CM coding system as a standard for developing problem lists. Because ICD-9-CM is a classification system, it is not designed to address the detail needed to accurately represent patient problems.

According to Fung, the same limitations still will exist within ICD-10-CM, even with the expanded detail that will be introduced. For example, the ICD-10-CM code G54.0 identifies brachial plexus disorders. In this case, one code is used to represent a group of conditions despite the fact there are many types of brachial plexus disorders depending on the underlying cause and the nerves involved. In SNOMED CT, there are 33 subtypes of brachial plexus disorders. “Clinically, there are many reasons why this disorder happens,” Fung says. “You really need additional detail because management may be very different depending on the specific condition.”

Separate but Complementary Functions
ICD-10, a classification system, and SNOMED CT, a clinical terminology system, each were designed to serve different purposes, according to Sue Bowman, MJ, RHIA, CCS, FAHIMA, senior director of coding policy and compliance for AHIMA who says neither should be viewed as superior to the other. “They are really intended for very different purposes,” she notes, pointing out that as a clinical terminology, SNOMED may be more useful for clinical applications, information retrieval, and research. “ICD does very well as a classification.”

At the same time, Fung points out that both systems tackle similar territory. “There is a big overlap in the domains they are covering,” he says. “In the new version of ICD [ICD-11], there will be a much closer link between the two systems.”

One way to differentiate the functions of SNOMED CT and ICD-10 is by looking at them from an input and output frame of reference, Bowman says. SNOMED CT can be utilized at the point of care as input, while the ICD classification is viewed as output for specific data uses, including reimbursement and statistical indexing.

“The major difference is that ICD is a classification which is limited to disease,” Bowman explains. “SNOMED CT provides a common language for systems to adopt for indexing, storing, retrieving, and aggregating clinical data across every specialty and health-care–related setting. The classification is useful for categorizing diseases and recording diagnostic and procedural information.”

Use of these systems will vary and most often depend on “the level of detail needed,” Bowman says. “If a researcher wants to know how many patients died with a diagnosis of heart attack last year, ICD-10 is enough. If they want more detail, such as what muscle of the heart was involved, they will need SNOMED CT.”

A More Advantageous Transition
SNOMED CT does not directly aid in the transition to the ICD-10 code set, but it does lay a foundation for improving the quality of the clinical information captured in an EHR. Fung says many clinicians will likely prefer working with SNOMED CT because ICD-10 is not clinician friendly. “For capture of clinical information, providers will prefer SNOMED because the terms are those that they are already familiar with,” he notes. “Another advantage is that providers will be able to find more specific terms.”

The detail of SNOMED CT also provides a better foundation for more advanced functions, such as clinical decision support at the point of care. Fung points out that the logical modeling of SNOMED CT lends itself to the more high-end functionality that will be required as meaningful use and other national initiatives continue to progress.

As clinicians use SNOMED CT, mapping capabilities can be leveraged within EHRs to provide a crosswalk between the clinical terminology system and ICD-10. Currently, maps providing links from SNOMED CT to ICD-10-CM can be accessed through the NLM. A separate map from SNOMED CT to ICD-10 (the international version) is being created through a collaboration between the World Health Organization and the IHTSDO.

According to Fung, a former cochair of the mapping special interest group with IHTSDO and the lead for the NLM’s SNOMED CT to ICD-10-CM mapping project, full mapping capabilities between the two systems will not be complete for some time because of the project’s extensive nature. “There are over 100,000 concepts in SNOMED that cover the same area as ICD-10,” he says. “We’ve made significant progress. In June of this year, we released a new version of the ICD-10-CM map that covers 35,000 concepts.” These concepts cover the most commonly used terms in problem lists and EHRs.

The recently updated Interactive Map-Assisted Generation of ICD Codes (I-MAGIC) demo tool, which showcases how the SNOMED CT to ICD-10-CM map can be used in an interactive, real-time manner through the NLM, can be accessed at http://imagic.nlm.nih.gov/imagic/code/map.

Yes, It Goes to 11
There’s bad news for health care organizations that moaned and groaned about ICD-10: Its next version is not too far off in the distance. According to Chris Chute, MD, DrPH, vice chair of data governance for the Mayo Clinic and chair of the ICD-11 development process at the World Health Organization, the latest incarnation currently is slated for a 2015 introduction. “The product ICD-11 will differ in many ways from previous ICDs,” he says, pointing to a closer link between the classification system and SNOMED CT. “It’s a very cordial and collaborative partnership.”

According to Fung, the partnership will ensure that ICD entries can be derived from SNOMED. “It will be much easier to define the relationship,” he says. “The concepts in ICD-11 will be logically defined using SNOMED concepts.”

From this network of multiple, cross-linked terms, Chute says the systems will have linearization—for example, morbidity linearization and mortality linearization—all linked back to a foundational component. While there still will be constraints with ICD, both ICD and SNOMED will have a common ontology element.

Chute says the systems’ close relationship will better enable linkage to clinical knowledge and clinical decision support. “ICD-11 will have the ability to add additional concepts to further define a term,” he explains, pointing out that ICD-11 will still not do as good a job as SNOMED. “We don’t want to compete with SNOMED; we just want to add more detail.”

— Selena Chavis is a Florida-based freelance journalist whose writing appears regularly in various trade and consumer publications covering everything from corporate and managerial topics to health care and travel.


The current SNOMED CT has evolved from its origin as the Systemized Nomenclature of Pathology in 1965 to a 21st-century terminology resource. Nevertheless, many health care professionals have only recently been introduced to the clinical terminology and its use, according to Rita Scichilone, MHSA, RHIA, CCS, CCS-P, senior advisor of global standards for AHIMA. “It’s a sophisticated machine language used in electronic systems around the world,” she notes.

To address the knowledge gap that currently exists in the industry, AHIMA is featuring a SNOMED CT Basics preconvention workshop on October 26 in conjunction with the association’s 85th Annual Convention and Exhibit in Atlanta.

For more information, visit www.ahima.org/convention/geninfo.aspx or www.ahima.org/convention/education.aspx.

— SC