International Classification of Diseases, (ICD-10-CM/PCS) Transition – Frequently Asked Questions

What do I need to know?

  • The transition to ICD-10-CM/PCS will take place on October 1, 2014
  • All users will transition on the same date
  • If your program is covered by the Health Insurance Portability and Accountability Act (HIPAA) then transitioning to ICD-10 code sets is mandatory (How do I know if I am covered by HIPAA?)
  • ICD-10 was implemented for mortality reporting in the U.S. in 1999


How do I know if my program will be affected by the transition?

Assess your program against the following questions to see if your program will be impacted by the transition to ICD-10-CM/PCS code sets.

  • Is your program covered by HIPAA? (e.g., is your program a health care provider that conducts electronic transactions with protected patient information? –OR– Is your government-funded program a health plan? If you are still not sure if your program is a covered entity please click here.)
  • Does your program receive or collect ICD-9-CM coded data from HIPAA-covered entities? (e.g., hospitals and health care providers)
  • Does your program receive or abstract verbatim diagnosis or procedure information that you assign ICD-9-CM codes to?
  • Do you define any health conditions, injuries or case reports based on diagnosis and/or procedure codes?
  • Does your program analyze public-use data files that are derived from or that include ICD-9-CM codes? (e.g., WISQARS, Hospital and Ambulatory Health Care Surveys, and MarketScan data)
  • Do you support systems that consume ICD-9-CM coded data?

If you answered yes to any of the above questions then you are likely affected by the transition to ICD-10 code sets. See Tips to help you start planning.


Why are we changing to ICD-10-CM/PCS code sets?

The U.S. has been using ICD-9-CM since 1979 and this coding scheme is not sufficiently robust to serve the health care needs of today and the future. The content is no longer clinically accurate, the number of available codes is limited and has been maxed out for some categories, and the coding structure is too restrictive. Further, mortality coding (death certificates) in the U.S. moved to ICD-10 in 1999 so the U.S. cannot directly compare morbidity diagnosis data to state and national mortality data. Similarly, most other developed countries have already transitioned to ICD-10 (for morbidity applications) so the U.S. cannot directly compare morbidity diagnosis data at the international level.


How different are ICD-10 code sets from ICD-9-CM and why is this transition any different from the annual code changes?

ICD-10 codes are very different from ICD-9 codes and have a completely different structure. Currently, ICD-9-CM codes are mostly numeric and have 3 to 5 digits. ICD-10 code sets are alphanumeric and contain 3 to 7 characters. ICD-10 code sets are more robust and descriptive with “one-to-many” matches in numerous instances. There are nearly 5 times as many diagnosis codes in ICD-10-CM than in ICD-9-CM, and nearly 19 times as many procedure codes in ICD-10-PCS than in ICD-9-CM volume 3.

Like ICD-9-CM codes, ICD-10-CM/PCS codes will be updated every year via the ICD-10-CM/PCS Coordination and Maintenance Committee. However, please note that a partial freeze has been implemented for ICD-10-CM/PCS and revisions will only be for new diseases/new technology procedures and any minor changes to correct reported errors. Regular updates will resume in 2015 (please go to the ICD-9-CM Coordination and Maintenance Committee page for more information).


What are the benefits of ICD-10 code sets?

ICD-10-CM/PCS has an improved structure, capacity, and flexibility for capturing advances in technology and medical knowledge. It incorporates greater clinical detail and level of specificity to provide better quality of data for many purposes. That greater clinical detail and specificity will also allow for more efficient tracking of health care and public health trends, quality of care issues, and evaluating health outcomes.

The greater number of codes will not necessarily make it more complex to use. In fact, the increase in codes should make it easier for health care providers to find the right code. The Alphabetic Index and available electronic coding tools will facilitate proper code selection for providers.


Will ICD-10 replace Current Procedural Terminology (CPT) procedure coding?

No. The switch to ICD-10 does not affect CPT coding for outpatient procedures. Like ICD-9-CM procedure codes, ICD-10-PCS codes are for hospital inpatient procedures only.


What happens if I do not switch to ICD-10?

Claims for all services and hospital inpatient procedures performed on or after the transition date (October 1, 2014) must use ICD-10 diagnosis and inpatient procedure codes (Note: this does not apply to CPT coding for outpatient procedures.) Therefore, claims that do not use ICD-10 diagnosis and inpatient procedure codes will not be processed and reimbursed.

If you currently receive already-coded ICD-9-CM data from health care providers or health plans, etc. you will have no choice about receiving data coded in ICD-10-CM/PCS beginning on the transition date because the entities that send you data will be coding those data in ICD-10 code sets.


What should public health programs that use ICD-9-CM codes do to prepare for the transition?

Start planning now if you haven’t already! Consider how this transition will impact your people, processes and systems that utilize ICD-coded data. See Tips to help point you to areas that might be impacted and for useful tools and training.


Where can I find the ICD-10 code sets?


What are General Equivalence Mappings (GEMs) and where can I find them?

General Equivalence Mappings are a tool that can assist with converting data from ICD-9-CM to ICD-10-CM and ICD-10-PCS. GEMs are a reference map, a practical reference dictionary to help a user navigate the complex meaning between the code sets. For example, one ICD-9-CM code can be represented by multiple ICD-10-CM codes and the GEMs show all of the possible alternative translations. Another example is that some concepts exist in ICD-10-CM that did not exist in ICD-9-CM, such as the Glasgow Coma Scale to assess level of consciousness. GEMs contain forwards and backwards mappings between ICD-9-CM and ICD-10-CM, and forward and backward mappings between ICD-9-CM and ICD-10-PCS. There are many GEMs files within each of the mapping categories. The GEMs were developed by the Centers for Medicare and Medicaid Services and CDC’s National Center for Health Statistics. Please note that GEMs between ICD-10 (World Health Organization version) and ICD-10-CM/PCS will be forthcoming.

The GEMs are useful in a number of ways. They are a tool to help you convert ICD-9 based systems or applications to ICD-10 based systems. They can help to create one-to-one backwards mappings (also known as “crosswalks”) from incoming ICD-10 based data to ICD-9 based legacy systems. They can also help convert ICD-9 historical data to an ICD-10 based representation for comparable longitudinal analysis.

To obtain GEMs for ICD-10-CM, scroll until you come to the latest release of ICD-10-CM and select “General Equivalence Mapping Files”.

To obtain GEMs for ICD-10-PCS, and select the latest “General Equivalence Mappings – Procedure Codes and Guide” from the Downloads section.

Please note that the GEMs are updated annually.


How do I know if I need to learn how to use the GEMs?

You might need to use GEMs if:

  • You are translating lists of codes, code tables, or other coded data
  • You are converting a system or application containing ICD-9-CM codes
  • You are creating a “one-to-one” applied mapping (aka crosswalk) between code sets that will be used in an ongoing way to translate records or other coded data
  • You want to study the differences in meaning between the ICD-9-CM classification systems and the ICD-10-CM/PCS classification systems by looking at the GEMs entries for a given code or area of classification

If you only need a general understanding of what the GEMs are for and will not be involved in mapping between code sets, then you may not need to learn how to use the GEMs.


Will there be General Equivalence Mappings between ICD-10 and ICD-10-CM?

Yes, NCHS plans to make available GEMs between ICD-10 (World Health Organization version) and ICD-10-CM (U.S. diagnoses). We will provide the link to these files when they become available.


What type of training will public health staff need for the ICD-10-CM/PCS transition?

It depends on how you and your staff use the codes. If you will need to assign ICD-10-CM or ICD-10-PCS codes to verbatim diagnosis/procedure information, you will need thorough training in either ICD-10-CM or ICD-10-PCS, or both code sets.

If you utilize already-coded ICD data, you will need to learn the new codes that apply to your data and conditions of interest. See the Training for available public health-oriented training options.


Who needs education on ICD-10-CM/PCS?

The following types of individuals within your organization may need some amount of education on the structure, benefits and/or changes seen in ICD-10-CM/PCS:

  • Epidemiologists
  • Statisticians
  • Public health scientists
  • Data analysts
  • Executive leadership
  • Program evaluation personnel
  • Medical officers
  • Researchers
  • Information technology and information systems personnel
  • Data security personnel
  • Project managers
  • Users of public-use data files

See Training for training options.