get_icd_codes: Get ICD Codes

In medicalcoder: A Unified and Longitudinally Aware Framework for ICD-Based Comorbidity Assessment

Get ICD Codes

Description

Retrieve a copy of the internal lookup table for all known ICD codes.

Usage

get_icd_codes(with.descriptions = FALSE, with.hierarchy = FALSE)

Arguments

with.descriptions	Logical scalar, if TRUE include the description of the codes.
with.hierarchy	Logical scalar, if TRUE include the ICD hierarchy.

Details

Sources

There are three sources of ICD codes.

• cms: Codes from the ICD-9-CM, ICD-9-PCS, ICD-10-CM, and ICD-10-PCS standards.

• who: Codes from World Health Organization.

• cdc: Codes from CDC Mortality coding standard.

Fiscal and Calendar Years

When reporting years there is a mix of fiscal and calendar years.

Fiscal years are the United States Federal Government fiscal years, running from October 1 to September 30. For example, fiscal year 2013 started October 1 2012 and ended on September 30 2013.

Calendar years run January 1 to December 31.

Within the ICD data there are columns known_start, known_end, assignable_start, assignable_end, desc_start and desc_end. For ICD codes with src == "cms", these are fiscal years. For codes with src == "cdc" or src == "who" these are calendar years.

known_start is the first fiscal or calendar year (depending on source) that the medicalcoder package as definitive source data for. ICD-9-CM started in the United States in fiscal year 1980. The CDC extracts included in medicalcoder span fiscal years 1997–2012; the CMS ICD-9-CM/PCS extracts start in fiscal year 2006 and run through fiscal year 2015. As such 1997 is the earliest "known start" for ICD-9 within medicalcoder.

known_end is the last fiscal or calendar year (depending on source) for which we have definitive source data for. For ICD-9-CM and ICD-9-PCS, CMS provides data through fiscal year 2015, while the CDC extracts stop at fiscal year 2012. For ICD-10-CM and ICD-10-PCS, which are active, it is just the last year of known data. ICD-10 from the WHO ends in 2019.

Header and Assignable Codes

"Assignable" indicates that the code is the most granular for the source. Ideally codes are reported with the greatest level of detail but that is not always the case. Also, the greatest level of detail can differ between sources. Example: C86 is a header code for cms and who because codes C86.0, C86.1, C86.2, C86.3, C86.4, C86.5, and C86.6 all exist in both standards. No code with a fifth digit exists in the who so all these four digit codes are 'assignable.' In the cms standard, C86.0 was assignable through fiscal year 2024. In fiscal year 2025 codes C86.00 and C86.01 were added making C86.0 a header code and C86.00 and C86.01 assignable codes.

Value

a data.frame

The default return has the following columns:

• icdv: Integer vector indicating if the code is from ICD-9 or ICD-10

• dx: Integer vector. 1 if the code is a diagnostic, (ICD-9-CM, ICD-10-CM, WHO, CDC Mortality), or 0 if the code is procedural (ICD-9-PCS, ICD-10-PCS)

• full_code: Character vector with the ICD code and any relevant decimal point

• code: Character vector with the compact ICD code omitting any relevant decimal point

• src: Character vector reporting the source of the information. See Details.

• known_start: Integer vector reporting the first known year of use. See Details.

• known_end: Integer vector reporting the last known year of use. See Details.

• assignable_start: Integer vector reporting the first known year the code was assignable. See Details.

• assignable_end: Integer vector reporting the last known year the code was assignable. See Details.

When with.descriptions = TRUE there are the following additional columns:

• desc: Character vector of descriptions. For cms codes descriptions from CMS are used preferentially over CDC.

• desc_start: Integer vector of the first year the description was used.

• desc_end: Integer vector of the last year the description was used.

When with.hierarchy = TRUE there are the following additional columns:

• chapter

• subchapter

• category

• subcategory

• subclassification

• subsubclassification

• extension

See Also

is_icd(), lookup_icd_codes(), vignette(topic = "icd", package = "medicalcoder")

Examples

icd_codes <- get_icd_codes()
str(icd_codes)

# Explore the change in the assignable year for C86 code between CMS and
# WHO
subset(get_icd_codes(), grepl("^C86$", full_code))
subset(get_icd_codes(), grepl("^C86\\.\\d$", full_code))
subset(get_icd_codes(), grepl("^C86\\.0(\\d|$)", full_code))

is_icd("C86", headerok = FALSE) # FALSE
is_icd("C86", headerok = TRUE)  # TRUE
is_icd("C86", headerok = TRUE, src = "cdc") # Not a CDC mortality code

lookup_icd_codes("^C86\\.0\\d*", regex = TRUE)

medicalcoder documentation built on Feb. 22, 2026, 5:08 p.m.