Utilizing General Equivalence Mappings in the Wake of ICD-10-CM Transition

Resources are available to assist in the coding translations brought on by ICD-10. This article gives an overview of utilizing GEMs as a crosswalk.

Even prior to the official Oct. 1, 2015, conversion date for ICD-10-CM, it was well known that healthcare providers would require assistance in translating codes from ICD-9. Among the resources created by the Centers for Medicare & Medicaid Services (CMS) are the General Equivalence Mappings (GEMs), which (as a whole) have been designed as a general-purpose translation tool (ie, crosswalk) to be used by those looking to convert coded data when trying to determine code-to-code links that will identify the most likely choice or compromise between codes. This is also referred to as one-to-one mapping. The second kind of mapping is one-code-to-many-codes mapping, which provides a comparison of all possible codes that may contain multiple meanings of the original code.

Mappings are useful to focus on code sets that are most important to the facility or to the physician’s practice. Prior to ICD-10 implementation, it was suggested by this author (among others) that wound care providers obtain the top 100 diagnoses in their facility types (eg, hospital-based outpatient departments [HOPDs]) in order to identify the most frequent diagnoses given so that the highest-volume diagnoses could be coded and translated prior to the implementation of ICD-10. In addition, GEMs can be used for verification of code assignments on updated forms, reports, and the physician’s office super bill or other billing documents. Many coders will use GEMs as a quick reference to validate coding accuracy. Below is an example of a one-to-one mapping of type 1 diabetes mellitus with ketoacidosis without coma:

ICD-9: 250.11 - Diabetes with ketoacidosis type 1, not stated as uncontrolled.

ICD-10: E10.10 - Type 1 diabetes mellitus with ketoacidosis without coma.

NOTE: In ICD-10 the clinical concept of controlled and uncontrolled was eliminated. Mapping is approximate. There are also many examples that illustrate the translation from one code to many. The best example of one to many would be the specific fracture codes.  Orthopedic fracture codes were once either open fractures or closed fractures. These codes have been widely expanded, especially by particular sites and complications involving fractures. This is just one example among numerous throughout the coding system.

The complete meaning of a code (defined as “all correctly coded conditions that would be classified to a code based on the code title, all associated tabular instructional notes, and all index references that refer to a code”) as a single unit goes in to what the most appropriate translation(s) of the code would actually mean. One ICD-9 or ICD-10 code can contain more than one diagnosis. For purposes of mapping, these are known as “combination codes.” A combination code consists of more than one diagnosis.

A few examples: 1) A combination code can consist of a chronic condition with a current acute manifestation, as in ICD-9 code 250.21 - Diabetes with hyperosmolarity, type 1, not stated as uncontrolled. 2) A combination code can consist of two acute conditions found together, as in ICD-10 code R65.21 - Severe sepsis with septic shock. This ICD-10 code would take two codes in ICD-9. 3) A combination code can consist of an acute condition and its external cause, as in a burn secondary to corrosive agent thrown at a patient — ICD-10 code category T20-T32.9. Also, use codes to describe the specific circumstances surrounding the burn (eg, an assault).

Caution on Utilizing GEMs

Remember that these mappings are the closest possible translations. However, it is imperative to look at GEMs as a guide and be sure the code or codes being selected make the best sense for the case attempting to be coded. To understand the exact code the payer may cover, verify the codes selected against any insurance policies or local coverage determinations (LCDs) that provide covered diagnosis codes. These covered codes might be different than those diagnosis codes identified in the GEMs. When using GEMs, if there are multiple codes that meet the diagnosis attempting to be coded, be sure to select the code or codes that best describe the scenario being coded. Also, refer to all coding and sequencing conventions in ICD-10. Payers may sometimes require a different sequence of codes than what the standard coding conventions might be. (Remember the ICD-9 coding of diabetic ulcer: payers wanted to see the ulcer first, then the diabetes code that was opposite of what the coding rules stated.)

Lastly, GEMs are not something to use to dump out all of one’s ICD-9 codes and have one-for-one matches for each and every code. With the addition of specific body sites, laterality, and expanded descriptions, it will be quite likely the code map will be one code mapping to multiple codes as possibilities. It is the coder’s role to determine the closest match to fit the case.

Practical Points

The following are some guidelines to remember regarding the assignment of ICD-10 for HOPDs and physician’s offices:

• Register and bill the patient for each encounter. (It is not advisable to do monthly billings, as this can result in diagnoses not matching the procedures or services performed since there are usually multiple modalities used over a monthly period.) It is extremely important to only list the diagnosis codes that pertain to the particular encounter being coded. Examples of this might include physicians performing two different procedures during the same encounter or the LCD requires a different primary diagnosis to be present for each procedure performed. Some billing systems will allow for a different primary diagnosis for each procedure while others may not. If the claim does not allow for different diagnosis, one might have to submit a claim for the two different procedures.

• Each visit requires a diagnosis code specific to the visit. Remember: The patient’s diagnosis often changes during the course of care due to a new problem, new wound site, complication of care, etc. Be sure to check any electronic health records to prevent unwanted diagnoses from appearing on the current record. Be sure to avoid using nonspecific codes, as they often lead toward denied claims, and specify the exact reason for the encounter as well as any other conditions that are relevant to the current encounter.

Donna J. Cartwright is senior director, reimbursement services, national policy and payer access at Integra LifeSciences Corp., Plainsboro, NJ, and an approved ICD-10 trainer by the American Health Information Management Association. She may be reached for questions at 609-936-2265 or at donna.cartwright@integralife.com.