Overview

Learn about medical coding systems and how we apply them.

Medical coding systems are common vocabularies that allow specific identification of different clinical concepts. There are a number of common and widely used medical coding systems, such as ICD-10-CM, SNOMED, and others. However, different healthcare IT systems use all kinds of coding systems - some standardized, some proprietary. Metriport enriches data with code system lookup, normalization, and cross-walks, so that the result is cohesive and more robust than it is at the source.

Common Medical Coding Systems

You can use the URLs of these systems from the table below to filter for relevant codes in your patient’s Consolidated Bundle.

Below is an overview of the most prevalent coding systems supported by Metriport and often found in the source documents:

Coding System	Identifiers	Purpose	FHIR Resources	Example	Maintained by
ICD-10-CM (International Classification of Diseases, 10th Revision, Clinical Modification)	OID: 2.16.840.1.113883.6.90 URL: http://hl7.org/fhir/sid/icd-10-cm	Encodes medical diagnoses and conditions	Condition	E11.9 → Type 2 diabetes mellitus without complications	U.S. National Center for Health Statistics (NCHS)
CPT (Current Procedural Terminology)	OID: 2.16.840.1.113883.6.12 URL: http://www.ama-assn.org/go/cpt	Encodes outpatient medical procedures and services	Procedure	0331T → Myocardial sympathetic innervation imaging, planar qualitative and quantitative assessment	American Medical Association (AMA)
CVX (Vaccine Codes)	OID: 2.16.840.1.113883.12.292 URL: http://hl7.org/fhir/sid/cvx	Identifies vaccines and vaccine groups	Immunization	125 → Novel Influenza-H1N1-09, live virus for nasal administration	U.S. Centers for Disease Control and Prevention (CDC)
SNOMED CT (Systematized Nomenclature of Medicine – Clinical Terms)	OID: 2.16.840.1.113883.6.96 URL: http://snomed.info/sct	Encodes comprehensive clinical terminology for conditions, findings, and procedures	Condition, Procedure, and others	44054006 → Diabetes mellitus type 2 (disorder)	SNOMED International
LOINC (Logical Observation Identifiers Names and Codes)	OID: 2.16.840.1.113883.6.1 URL: http://loinc.org	Encodes laboratory and clinical observations	Observation, Encounter, and others	718-7 → Hemoglobin [Mass/volume] in Blood	Regenstrief Institute
NDC (National Drug Code)	OID: 2.16.840.1.113883.6.69 URL: http://hl7.org/fhir/sid/ndc	Identifies drug products marketed in the U.S.	Medication	0002-8215-01 → insulin human (Humulin R) 100 [iU]/mL Parenteral Injection, Solution, 1 VIAL, MULTI-DOSE in 1 CARTON (0002-8215-01) / 10 mL in 1 VIAL, MULTI-DOSE	U.S. Food and Drug Administration (FDA)
RxNorm	OID: 2.16.840.1.113883.6.88 URL: http://www.nlm.nih.gov/research/umls/rxnorm	Normalizes drug names and clinical drugs	Medication	311036 → HumuLIN R 100 UNT/ML Injectable Solution	U.S. National Library of Medicine (NLM)

Other Clinical Classification Systems

These systems are typically not provided in the source documents, but are added by Metriport:

Coding System	Purpose	FHIR Resources	Example	Maintained by
CCSR (Clinical Classifications Software Refined)	Groups ICD-10-CM diagnosis codes into clinically meaningful categories across body systems	Condition	END002 → Diabetes mellitus without complication	U.S. Agency for Healthcare Research and Quality (AHRQ)
HCC (Hierarchical Condition Categories)	Groups ICD-10-CM diagnosis codes into hierarchical categories used for risk adjustment and reimbursement	Condition	18 → Diabetes with chronic complications	U.S. Centers for Medicare & Medicaid Services (CMS)
CCIR (Chronic Condition Indicator Refined)	Classifies ICD-10-CM diagnosis codes as chronic or nonchronic across 18 clinical condition categories	Condition	C → Chronic	U.S. Agency for Healthcare Research and Quality (AHRQ)

Representation in FHIR

Each of these coding systems appears in FHIR as elements of coding, category, or extension arrays.

Here’s a subset of attributes you can expect to find in a Condition resource, displaying how Metriport uses different coding systems to hydrate the clinical data:

{
  "resourceType": "Condition",
  "code": {
    "text": "Unspecified atrial fibrillation",
    "coding": [
      {
        "code": "I48.91",
        "display": "Unspecified atrial fibrillation",
        "system": "http://hl7.org/fhir/sid/icd-10-cm"
      },
      {
        "code": "49436004",
        "system": "http://snomed.info/sct",
        "display": "Atrial fibrillation (disorder)"
      },
      {
        "code": "427.31",
        "display": "Atrial fibrillation, unspecified type (HCC)",
        "system": "http://terminology.hl7.org/CodeSystem/ICD-9CM-diagnosiscodes"
      }
    ]
  },
  "category": [
    {
      "coding": [
        {
          "system": "http://terminology.hl7.org/CodeSystem/condition-category",
          "code": "encounter-diagnosis",
          "display": "Encounter Diagnosis"
        }
      ],
      "text": "Encounter Diagnosis"
    },
    {
      "coding": [
        {
          "system": "https://hcup-us.ahrq.gov/toolssoftware/ccsr/ccs_refined.jsp",
          "code": "CIR",
          "display": "Diseases of the circulatory system"
        }
      ],
      "text": "Diseases of the circulatory system"
    }
  ],
  "extension": [
    {
      "url": "http://hl7.org/fhir/StructureDefinition/condition-related",
      "valueCoding": {
        "code": "C",
        "display": "Chronic",
        "system": "https://public.metriport.com/fhir/StructureDefinition/condition-chronicity.json"
      }
    },
    {
      "url": "https://public.metriport.com/fhir/StructureDefinition/condition-hcc.json",
      "valueCodeableConcept": {
        "coding": [
          {
            "system": "http://terminology.hl7.org/CodeSystem/cmshcc",
            "display": "Unspecified atrial fibrillation",
            "version": "v24",
            "code": "96"
          }
        ]
      }
    }
  ]
}