Purpose
As we move further from the 2015 transition to ICD-10, we see fewer ICD-9-CM codes being sent in the data, but still enough to warrant inclusion in syndrome definitions, Posit Workbench and SAS Studio analyses, and data processing. Accommodating ICD-9 codes can be difficult in practice. Use this guide to identify and address these issues.
The need to phase out ICD-9 codes
In early May 2023, the Community of Practice Subcommittee met to discuss topics including ICD-9-CM discharge diagnosis values in syndromic surveillance data. According to the PHIN Messaging Guide Release 1.9, ICD-9-CM values are acceptable in certain fields for syndromic surveillance messaging. As we move further from the 2015 transition to ICD-10, we see fewer ICD-9-CM codes being sent in the data, but still enough to warrant inclusion in syndrome definitions, Posit Workbench and SAS Studio analyses, and data processing.
Accommodating ICD-9 codes can be difficult in practice. For example, "V" and "E" codes look similar in both ICD-9-CM and ICD-10-CM, which can cause some syndrome queries to give inaccurate results. Not only does ICD-9-CM overlap with ICD-10-CM, but non-decimal forms of numerical ICD-9-CM can pull the first portions of SNOMED-CT codes if not queried to the final character.
Using queries to closely approximate and search for the three major code sets (ICD-9-CM, ICD-10-CM, and SNOMED-CT), we can see the following breakdown for the first quarter of 2023 across all NSSP data:
- Approximately 231,000 (0.5%) emergency department (ED) visits matched the ICD-9-CM pattern query, indicating these ED visits received at least one ICD-9-CM code in the discharge diagnosis field.
- Approximately 41,000 (0.08%) ED visits matched the ICD-9-CM query and also did not match the ICD-10-CM nor SNOMED-CT query, indicating these ED visits likely had only ICD-9-CM codes in the discharge diagnosis field.
We see the frequency of ICD-9-CM vary widely by HHS region, by emergency and non-emergency facilities, and by the age of the data. We have also noticed a trend we suspect is from facilities using ICD-9-CM and then filling in with other code sets later.
Help from NSSP
If you would like to tackle your site's facilities sending ICD-9-CM, follow our recommended approach.
Identify issues
Identify facilities that are sending ICD-9-CM. This could be specific facilities, certain types of visits, a health information exchange (HIE), or specific electronic health record (EHR) products or vendors.
You can explore these queries in ESSENCE by visiting the myESSENCE dashboard library titled "What diagnosis codes do I have?" To go directly to these queries, please see the links below.
Note: The queries listed below search for approximations of codes. Review line-level data to ensure the facility is sending ICD-9-CM.
Reach out
Reach out to the identified facilities, EHR vendors, or HIE. It may be helpful to provide examples so the sender can connect what we receive with the fields sent. Ask your facility/EHR vendor/HIE contacts about correction steps, alternative fields, or code set translations that may be available.