Diagnosis (ICD-9 and ICD-10)

Update: MLN (Medicare Learning Network) published this pdf on ICD-10 on June 22, 2010


The diagnosis is the identification of a patient’s disease or medical condition and is currently (2010) described by a six place numeric identifier (5 digits and one decimal) called the International Classification of Diseases, Ninth Revision or the ICD-9 code.  On October 1, 2013, the United States will move to ICD-10.  The International version of ICD should not be confused with national Clinical Modifications of ICD that include frequently much more detail, and sometimes have separate sections for procedures, so the new US ICD-10 CM has more than 150,000 codes.

The differences are:

ICD-9 codes consist of 3-5 digits:
Ӣ Chapters 1-7 are numeric
”¢ Supplemental chapters: the first digit is alpha (E or V) and the rest are numeric

ICD-10-CM codes consist of 3-7 alphanumeric characters:
Ӣ Digit 1 is alpha
Ӣ Digit 2 is numeric
Ӣ Digits 3-7 are alpha or numeric

2009 totals, according to the U.S. Department of Health and Human Services:
ICD-9-CM: 17,000
Diagnosis: 13,000
Procedure: 4,000

ICD-10: 140,694
Diagnosis (ICD-10-CM): 68,105
Procedure (ICD-10-PCS): 72,589

Healthcare Information Management, Inc. states:

The ICD-10-CM is divided into an index. The first is the alphabetical list of terms and their corresponding code. The second is the Tabular List, a chronological list of codes divided into chapters that represent different conditions or body systems. There are also two parts to the Index ”“ the Index to External Causes of Injury and the Index for Diseases and Injury. The Index and Tabular portions of the ICD-10-CM include the conventions and structural notes.

The Tabular List contains alphanumeric categories, subcategories, and codes. When a three character category has no more subdivisions, it is considered a code. Each level of subdivision after the category is a subcategory. The ”˜code’ is considered complete once there are no more subcategories. A code indicated to have a 7th character is considered incomplete without the missing character.

In order to be reportable, only a complete ”˜code’ can be used. Subcategories or diagnoses that are not complete cannot be used for reporting. When there is an unknown subcategory, the place holder X is allowable in either the 5th or 6th position. This placeholder allows for the future addition of characters, thereby accommodating expansion when needed. The notes in the Tabular List will indicate categories where a 7th character is required.

ICD-9 codes are arranged thusly:

And, the ICD-10 is arranged like this:

Chapter Blocks Title
I A00-B99 Certain infectious and parasitic diseases
II C00-D48 Neoplasms
III D50-D89 Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
IV E00-E90 Endocrine, nutritional and metabolic diseases
V F00-F99 Mental and behavioural disorders
VI G00-G99 Diseases of the nervous system
VII H00-H59 Diseases of the eye and adnexa
VIII H60-H95 Diseases of the ear and mastoid process
IX I00-I99 Diseases of the circulatory system
X J00-J99 Diseases of the respiratory system
XI K00-K93 Diseases of the digestive system
XII L00-L99 Diseases of the skin and subcutaneous tissue
XIII M00-M99 Diseases of the musculoskeletal system and connective tissue
XIV N00-N99 Diseases of the genitourinary system
XV O00-O99 Pregnancy, childbirth and the puerperium
XVI P00-P96 Certain conditions originating in the perinatal period
XVII Q00-Q99 Congenital malformations, deformations and chromosomal abnormalities
XVIII R00-R99 Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
XIX S00-T98 Injury, poisoning and certain other consequences of external causes
XX V01-Y98 External causes of morbidity and mortality
XXI Z00-Z99 Factors influencing health status and contact with health services
XXII U00-U99 Codes for special purposes

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