What is the ICD?

ICD stands for the International Classification of Disease. The ICD provides a method of classifying diseases, injuries, and causes of death. The World Health Organization (WHO) publishes the ICDs to standardize the methods of recording and tracking instances of diagnosed disease all over the world, making it possible to conduct research on diseases, their causes, and their treatments.

The first International Classification of Diseases, Adapted for Indexing of Hospital records and Operation Classification (ICDA) was published in 1962 by the U.S Public Health Services. ICD-7 was released to meet the growing needs of hospitals. This was followed by ICDA-8, which was published for coding morbidity and mortality statistics. The last release, which was ICD-9 (ICD-9-CM for the US) was published greater than 30 years ago.

ICD-10 was first published by the World Health Organization in 1992. This version, which is what ICD-10-CM is based on, was adopted by the United States in 1999 for cause of death (death certificates) only. In October 2015, the National Center for Health Statistics (NCHS), the Federal agency responsible for the use of the International Classification of Diseases and Related Health Problems, released the clinical modification (CM) of the classification for morbidity purposes. The United States is the only country using ICD-10-CM. In addition, ICD-10-PCS was released, which is for procedures (replacement for ICD-9-CM, volume 3, Procedures).

ICD-10-CM was developed following a thorough evaluation by a Technical Advisory Panel and extensive additional consultation with physician groups, clinical coders, and other to assure clinical accuracy and utility. Notable improvements in the content and format include:

  • Greater specificity in code assignment
  • Incorporation of common 4th and 5th digit sub classifications
  • Addition of a sixth character
  • Creation of combination diagnosis/symptom codes to reduce number of codes needed to fully describe a condition
  • Codes indicating laterality in paired organs
  • Additional information relevant to ambulatory and managed care encounters
  • Expanded injury codes
  • Ability to allow further expansion which was not possible with ICD-9-CM

The move for the rest of the medical community from ICD-9-CM to ICD-10-CM increases both the numbers of categories and subcategories available for coding as well as the construction of the codes, themselves. For the neoplasm chapter, ICD-9-CM had 11 categories and 66 subcategories, while ICD-10-CM has 17 categories and 113 subcategories, allowing for more information to be included in a code.

Updated: December 3, 2018