Navigating the Evolution: A Comparative Analysis of ICD-10 and ICD-11 Diagnosis Codes

The International Classification of Diseases (ICD) is a globally used diagnostic tool for epidemiology, health management, and clinical purposes. It is also the international standard for reporting diseases and health conditions. The World Health Organization (WHO) oversees the ICD and periodically revises it to account for advances in medicine and medical terminology.

The most recent versions are ICD-10, which WHO endorsed in 1990, and ICD-11, endorsed in May 2019. According to those at, both provide codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or disease. The upcoming implementation of ICD-11 diagnosis codes will affect healthcare systems worldwide. In the following paragraphs, we will examine the key differences between ICD-10 and ICD-11 and what the transition will entail.

Key Differences Between ICD-10 and ICD-11

While ICD-10 contains around 14,400 different codes, the new ICD-11 nearly doubles that number to around 55,000 codes. This reflects the tremendous growth in medical knowledge over the past few decades. ICD-11 better captures data on injuries, emerging diseases, sexual health, deaths during pregnancy/childbirth, traditional medicine, and causes of mortality.

Some categories have been expanded significantly. For instance, the neoplasms section contains over triple the number of codes in ICD-11 compared to ICD-10. This allows for greater specificity in cancer diagnoses.

ICD-11 marks a shift towards encoding diagnostic information rather than merely the disease name. For example, ICD-10 has a single code for hypothyroidism, while ICD-11 distinguishes congenital, acquired, and drug-induced hypothyroidism. This extra detail improves statistical reporting and health management.

The codes themselves have been restructured and expanded to seven characters instead of letters and numbers. Having uniform seven character codes facilitates digital usage and integration. ICD-11 is more intuitive to users with its alphanumerical codes and makes it easier to retrieve related codes algorithmically.

The codes are organized differently as well. ICD-11 groups related conditions more logically, partly based on severity. For example, uncomplicated diabetes mellitus is separate from diabetes mellitus with complications. The neoplasms section puts hematopoietic tumors before other types based on disease burden.

ICD-11 better reflects modern medicine with new chapters on traditional medicine, sexual health, sleep disorders, medicolegal issues, and even health interventions. Traditional medicine conditions can now be recorded. New sexual health codes describe issues like gender incongruence. Coding now exists for assessment scales like the Glasgow Coma Scale.

Implementing ICD-11 Diagnosis Codes

WHO released ICD-11 in 2018, but countries can still use ICD-10 for several years during the transition. ICD-10 had a phased implementation too, adopted in 1990 but not required for reporting in the U.S. until 2015. The transition to ICD-11 will affect nearly every part of the healthcare system.

Clinical documentation must use the new codes properly, so electronic health systems and software must be extensively updated. Publishers need to incorporate the new codes into training materials, manuals, and guidelines. Reporting standards will change. Data warehouse structures may need reorganizing to accommodate the extra character and different organization.

Planning is critical when shifting to ICD-11 diagnosis codes. Providers should verify with payers and public health agencies when the new codes will be required or recommended. Software vendors and IT departments may need several years to develop compliant systems and workflows. Clinical documentation specialists ought to be trained well in advance.


The implementation of ICD-11 diagnosis codes promises to improve the accuracy and specificity of medical coding and statistics. It reflects current medical knowledge and leverages the power of digital health systems. But migrating from ICD-10 is still an arduous process requiring advanced planning and phased execution.


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