ICD-Mappings

This python tool enables a variety of mappings of ICD codes (International Classification of Diseases) to different medical concepts with a single line of code.

Latest data refresh: ICD-10 chapter and block mappings were fetched from the latest available code ranges on 2026-04-27.

Supported Mappings

From ICD-9 CM diagnostic codes to:

• ICD-10 CM: International Classification of Diseases version 10 Clinical Modification.
• ICD-9 Chapters: 19 Chapters of ICD-9-CM.
• CCS: Clinical Classification Software. All 14k ICD-9-CM diagnostic codes can be mapped into just 283 clinical categories.
• CCI: Chronic Condition Indicator. True or False whether the diagnostic is chronic; parent-code inference is enabled by default for target='cci' and can be disabled with allow_parent_inference=False.
• CCC Category: Pediatric Complex Chronic Conditions Classification System v3 - Category (15 categories).
• CCC Subcategory: Pediatric Complex Chronic Conditions Classification System v3 - Subcategory (64 subcategories).

From ICD-10 CM diagnostic codes to:

• ICD-9 CM: International Classification of Diseases version 9 Clinical Modification
• ICD-10 CM Chapters: 22 Chapters of ICD-10 CM. Extraction date 2026-04-27
• ICD-10 CM Blocks: 226 Blocks of ICD-10 CM. Extraction date 2026-04-27
• CCS(R): Clinical Classification Software (Refined). All the 70k ICD-10-CM diagnostic codes can be mapped into just 530 clinical categories.
• CCI(R): Chronic Condition Indicator (Refined). True or False whether the diagnostic is chronic; parent-code inference is enabled by default for target='ccir' and can be disabled with allow_parent_inference=False.
• CCC Category: Pediatric Complex Chronic Conditions Classification System v3 - Category (15 categories).
• CCC Subcategory: Pediatric Complex Chronic Conditions Classification System v3 - Subcategory (64 subcategories).

Installation

pip install icd-mappings

Usage

Below are some examples on how to use this tool for both the Mapper and Validator classes

Mapper

This class allows you to map between ontologies.

from icdmappings import Mapper

mapper = Mapper()

icd9code = '29410' 
mapper.map(icd9code, source='icd9', target='ccs')
>>> '653'

# you can pass any Iterable of codes (list, numpy array, pandas Series, you name it)
icd9codes = ['29410', '5362', 'NOT_A_CODE', '3669']
mapper.map(icd9codes, source='icd9', target='ccs')
>>> ['653', '141', None, '86']

# which of these diagnostics are chronic?
mapper.map(icd9codes, source='icd9', target='cci')
>>> [True, False, None, True]

# For CCI, allow_parent_inference is True by default and maps truncated parent codes only when all mapped children agree.
mapper.map('567', source='icd9', target='cci')
>>> False

# You can explicitly disable parent-code inference.
mapper.map('567', source='icd9', target='cci', allow_parent_inference=False)
>>> None

# icd9 to icd10
mapper.map(icd9codes, source='icd9', target='icd10')
>>> ['F0280', 'R111000', None, 'H269']

# icd10 to chapters and blocks
icd10codes = ['F0280', 'R111000', 'NOT_A_CODE', 'H269', 'H27.8']
mapper.map(icd10codes, source='icd10', target='chapter')
>>> ['5', '18', None, '7', '7']

mapper.map(icd10codes, source='icd10', target='block')
>>> ['F00-F09', 'R10-R19', None, 'H25-H28', 'H25-H28']

# allow_parent_inference is True by default for CCIR and maps truncated parent codes only when all mapped children agree.
mapper.map('H81.0', source='icd10', target='ccir')
>>> True

# You can explicitly disable parent-code inference.
mapper.map('H81.0', source='icd10', target='ccir', allow_parent_inference=False)
>>> None


# Pediatric Complex Chronic Conditions (CCC)
icd9codes = ['135', '179', '243']
mapper.map(icd9codes, source='icd9', target='ccc_category')
>>> ['hemato_immu', 'malignancy', 'metabolic']

mapper.map(icd9codes, source='icd9', target='ccc_subcategory')
>>> ['Sarcoidosis', 'Neoplasms', 'Endocrine disorders']

# And many more... You can check all available mappers this way
mapper.show_mappers()
>>> From icd9 to:
>>>         - cci
>>>         - ccs
>>>         - chapter
>>>         - icd10
>>>         - ccc_category
>>>         - ccc_subcategory
>>> From icd10 to:
>>>         - icd9
>>>         - block
>>>         - chapter
>>>         - ccsr
>>>         - ccir
>>>         - ccc_category
>>>         - ccc_subcategory

Validator

This class helps you validate codes for a given ontology. Currently supports ICD9 and ICD10 codes.

from icdmappings import Validator

validator = Validator()

icd9code = '3591'

validator.validate(icd9code, expects='icd9_diagnostic')
>>> True

icd9codes = ['3591','NOT_A_CODE', '00321']
validator.validate(icd9codes, expects='icd9_diagnostic')
>>> [True, False, True]

# can also check procedure codes
icd9codes = ['3582', '5731', 'NOT_A_CODE']
validator.validate(icd9codes, expects='icd9_procedure')
>>> [True, True, False]

# likewise for ICD10

icd10code = 'B530'
validator.validate(icd10code, expects='icd10_diagnostic')
>>> True

Feature requests

Feel free to request a new functionality or report a bug by creating a new issue.

Acknowledgments

Miguel Cardoso for building the initial version of the icd9->ccs pipeline

Supporting the Project

If this tool adds value to your use case, give it a star in its github page. Also, feedback is welcome in the issues page.