Tuesday, March 18, 2025

Chat GPT Answers a Question about U.S. ICD-10-CM

 I can't guarantee the precision of this AI answer but I believe it's directionally correct.

QUESTION

ICD-10 is the "international" classification of disease.   But it is also maintained by CDC and CMS, and edited and updated by them regularly.  Do what extent is our ICD-10 CM in the US "international" and to what extent "local" due to these CDC CMS updates?

### Chat GPT 4o:

ICD-10-CM (Clinical Modification) in the U.S. is both international and local due to how it is derived from and modified from the global ICD-10 standard.

International Aspects

  1. Core Structure from WHO – The ICD-10 system itself is maintained by the World Health Organization (WHO) as an international standard for disease classification.
  2. Fundamental Coding Categories – The broad chapters, category structures, and many codes remain consistent with WHO’s ICD-10 to ensure international comparability.
  3. Crosswalks with Global Systems – Because it is derived from ICD-10, ICD-10-CM maintains alignment for global epidemiological and statistical tracking.

Local (U.S.-Specific) Aspects

  1. Expanded Clinical Modification (CM) – The U.S. CDC and CMS developed ICD-10-CM to significantly expand ICD-10, adding thousands of additional diagnosis codes tailored to U.S. clinical and billing needs.
  2. Annual Updates by U.S. Agencies – Unlike the WHO version of ICD-10, which is updated less frequently, ICD-10-CM is updated annually by CDC and CMS based on U.S. healthcare policy, reimbursement needs, and clinical practice changes.
  3. U.S.-Specific Codes – Many codes are unique to ICD-10-CM and do not exist in the WHO’s ICD-10, such as codes for:
    • Specific social determinants of health (e.g., Z codes for housing or food insecurity)
    • U.S.-centric diseases and conditions (e.g., opioid epidemic-related codes)
    • Greater specificity for certain conditions to align with U.S. billing and compliance needs.
  4. CMS Influence on Coding Rules – The Medicare & Medicaid Services (CMS) define how ICD-10-CM codes are used for reimbursement, which adds an additional layer of U.S.-specific coding guidance that differs from how ICD-10 is used globally.

Conclusion

While ICD-10-CM is rooted in the WHO’s ICD-10, it has evolved into a heavily modified version tailored to U.S. healthcare, reimbursement, and public health tracking. This means international comparisons remain possible at the broader category level, but at the specific code level, ICD-10-CM is highly localized.