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curl -X GET "https://api.omophub.com/v1/domains?include_concept_counts=true&include_statistics=true&include_examples=true" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json"

{
  "success": true,
  "data": {
    "domains": [
    {
      "domain_id": "Condition",
      "domain_name": "Condition",
      "domain_concept_id": 19,
      "description": "Medical conditions, diseases, disorders, and clinical findings that represent states of health or illness",
      "category": "clinical",
      "concept_count": 845672,
      "standard_concept_count": 423891,
      "primary_vocabularies": ["SNOMED", "ICD10CM", "ICD10", "ICD9CM"],
      "color_hex": "#e74c3c",
      "icon_name": "medical-cross",
      "statistics": {
        "total_concepts": 845672,
        "vocabulary_distribution": {
          "SNOMED": 387421,
          "ICD10CM": 98234,
          "ICD10": 87456,
          "ICD9CM": 76543,
          "Read": 45231,
          "Others": 150787
        },
        "concept_class_distribution": {
          "Clinical Finding": 425891,
          "Disorder": 234567,
          "3-char billing code": 98234,
          "4-char billing code": 87456
        },
        "growth_trend": {
          "concepts_added_last_year": 12847,
          "concepts_deprecated_last_year": 3421,
          "average_monthly_growth": 0.12
        },
        "usage_frequency": 0.89,
        "relationship_density": 4.2
      },
      "examples": [
        {
          "concept_id": 201826,
          "concept_name": "Type 2 diabetes mellitus",
          "concept_code": "44054006",
          "vocabulary_id": "SNOMED",
          "concept_class_id": "Clinical Finding"
        },
        {
          "concept_id": 320128,
          "concept_name": "Essential hypertension",
          "concept_code": "59621000",
          "vocabulary_id": "SNOMED", 
          "concept_class_id": "Clinical Finding"
        },
        {
          "concept_id": 4329847,
          "concept_name": "Myocardial infarction",
          "concept_code": "22298006",
          "vocabulary_id": "SNOMED",
          "concept_class_id": "Clinical Finding"
        }
      ],
      "valid_start_date": "1970-01-01T00:00:00Z",
      "valid_end_date": "2099-12-31T00:00:00Z"
    },
    {
      "domain_id": "Drug",
      "domain_name": "Drug",
      "domain_concept_id": 13,
      "description": "Medications, pharmaceutical products, drug ingredients, and therapeutic substances",
      "category": "clinical",
      "concept_count": 652341,
      "standard_concept_count": 198765,
      "primary_vocabularies": ["RxNorm", "RxNorm Extension", "NDC", "SNOMED"],
      "color_hex": "#3498db",
      "icon_name": "pill",
      "statistics": {
        "total_concepts": 652341,
        "vocabulary_distribution": {
          "RxNorm": 234567,
          "RxNorm Extension": 198432,
          "NDC": 145678,
          "SNOMED": 45231,
          "Others": 28433
        },
        "concept_class_distribution": {
          "Clinical Drug": 98765,
          "Branded Drug": 87654,
          "Generic Drug": 76543,
          "Ingredient": 45678
        },
        "growth_trend": {
          "concepts_added_last_year": 23456,
          "concepts_deprecated_last_year": 8765,
          "average_monthly_growth": 0.28
        },
        "usage_frequency": 0.76,
        "relationship_density": 6.8
      },
      "examples": [
        {
          "concept_id": 1503297,
          "concept_name": "Metformin",
          "concept_code": "6809",
          "vocabulary_id": "RxNorm",
          "concept_class_id": "Ingredient"
        },
        {
          "concept_id": 1308216,
          "concept_name": "Lisinopril 10 MG Oral Tablet",
          "concept_code": "314077",
          "vocabulary_id": "RxNorm",
          "concept_class_id": "Clinical Drug"
        }
      ],
      "valid_start_date": "1970-01-01T00:00:00Z",
      "valid_end_date": "2099-12-31T00:00:00Z"
    },
    {
      "domain_id": "Procedure",
      "domain_name": "Procedure",
      "domain_concept_id": 10,
      "description": "Medical procedures, surgical interventions, diagnostic tests, and therapeutic interventions",
      "category": "clinical",
      "concept_count": 456789,
      "standard_concept_count": 234561,
      "primary_vocabularies": ["SNOMED", "ICD10PCS", "HCPCS"],
      "color_hex": "#2ecc71",
      "icon_name": "stethoscope",
      "statistics": {
        "total_concepts": 456789,
        "vocabulary_distribution": {
          "SNOMED": 198765,
          "ICD10PCS": 76543,
          "HCPCS": 45678,
          "Others": 48149
        },
        "usage_frequency": 0.64,
        "relationship_density": 3.9
      },
      "examples": [
        {
          "concept_id": 4273391,
          "concept_name": "Coronary artery bypass graft",
          "concept_code": "232717009",
          "vocabulary_id": "SNOMED",
          "concept_class_id": "Procedure"
        }
      ],
      "valid_start_date": "1970-01-01T00:00:00Z",
      "valid_end_date": "2099-12-31T00:00:00Z"
    }
    ],
    "domain_summary": {
    "total_domains": 23,
    "total_concepts_across_domains": 3456789,
    "most_common_vocabularies": ["SNOMED", "RxNorm", "ICD10CM", "LOINC"],
    "domain_categories": {
      "clinical": 15,
      "administrative": 4,
      "derived": 3,
      "metadata": 1
      }
    }
  },
  "meta": {
    "request_id": "req_domains_789",
    "timestamp": "2024-12-22T10:30:00Z",
    "vocab_release": "2025.2"
  }
}
This endpoint provides information about all domains available in the OMOP vocabulary system. Domains represent high-level categorizations that group medical concepts by their semantic meaning, such as Condition, Drug, Procedure, and others.

​
Query Parameters

​
vocabulary_ids
string
Filter domains to those used by specific vocabularies
Example: SNOMED,ICD10CM,RxNorm
​
include_concept_counts
boolean
default:"false"
Include counts of concepts within each domain
Note: Required when using sort_by=concept_count
​
include_statistics
boolean
default:"false"
Include detailed statistics and usage information for each domain
Note: Required when using sort_by=usage_frequency
​
include_examples
boolean
default:"false"
Include example concepts for each domain
​
standard_only
boolean
default:"true"
Only include domains containing standard concepts
​
active_only
boolean
default:"true"
Only return domains with active concepts
​
sort_by
string
default:"domain_name"
Sort domains by specified criteria
Options:
  • domain_name (or name as alias) - Sort by domain name alphabetically
  • concept_count - Sort by number of concepts (requires include_concept_counts=true)
  • usage_frequency - Sort by usage statistics (requires include_statistics=true)
​
sort_order
string
default:"asc"
Sort order for results
Options: asc, desc

​
Response

​
domains
array
Array of domain objects with their properties
​
domain_summary
object
Summary information about all domains
​
meta
object
Response metadata and additional information
curl -X GET "https://api.omophub.com/v1/domains?include_concept_counts=true&include_statistics=true&include_examples=true" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json"

{
  "success": true,
  "data": {
    "domains": [
    {
      "domain_id": "Condition",
      "domain_name": "Condition",
      "domain_concept_id": 19,
      "description": "Medical conditions, diseases, disorders, and clinical findings that represent states of health or illness",
      "category": "clinical",
      "concept_count": 845672,
      "standard_concept_count": 423891,
      "primary_vocabularies": ["SNOMED", "ICD10CM", "ICD10", "ICD9CM"],
      "color_hex": "#e74c3c",
      "icon_name": "medical-cross",
      "statistics": {
        "total_concepts": 845672,
        "vocabulary_distribution": {
          "SNOMED": 387421,
          "ICD10CM": 98234,
          "ICD10": 87456,
          "ICD9CM": 76543,
          "Read": 45231,
          "Others": 150787
        },
        "concept_class_distribution": {
          "Clinical Finding": 425891,
          "Disorder": 234567,
          "3-char billing code": 98234,
          "4-char billing code": 87456
        },
        "growth_trend": {
          "concepts_added_last_year": 12847,
          "concepts_deprecated_last_year": 3421,
          "average_monthly_growth": 0.12
        },
        "usage_frequency": 0.89,
        "relationship_density": 4.2
      },
      "examples": [
        {
          "concept_id": 201826,
          "concept_name": "Type 2 diabetes mellitus",
          "concept_code": "44054006",
          "vocabulary_id": "SNOMED",
          "concept_class_id": "Clinical Finding"
        },
        {
          "concept_id": 320128,
          "concept_name": "Essential hypertension",
          "concept_code": "59621000",
          "vocabulary_id": "SNOMED", 
          "concept_class_id": "Clinical Finding"
        },
        {
          "concept_id": 4329847,
          "concept_name": "Myocardial infarction",
          "concept_code": "22298006",
          "vocabulary_id": "SNOMED",
          "concept_class_id": "Clinical Finding"
        }
      ],
      "valid_start_date": "1970-01-01T00:00:00Z",
      "valid_end_date": "2099-12-31T00:00:00Z"
    },
    {
      "domain_id": "Drug",
      "domain_name": "Drug",
      "domain_concept_id": 13,
      "description": "Medications, pharmaceutical products, drug ingredients, and therapeutic substances",
      "category": "clinical",
      "concept_count": 652341,
      "standard_concept_count": 198765,
      "primary_vocabularies": ["RxNorm", "RxNorm Extension", "NDC", "SNOMED"],
      "color_hex": "#3498db",
      "icon_name": "pill",
      "statistics": {
        "total_concepts": 652341,
        "vocabulary_distribution": {
          "RxNorm": 234567,
          "RxNorm Extension": 198432,
          "NDC": 145678,
          "SNOMED": 45231,
          "Others": 28433
        },
        "concept_class_distribution": {
          "Clinical Drug": 98765,
          "Branded Drug": 87654,
          "Generic Drug": 76543,
          "Ingredient": 45678
        },
        "growth_trend": {
          "concepts_added_last_year": 23456,
          "concepts_deprecated_last_year": 8765,
          "average_monthly_growth": 0.28
        },
        "usage_frequency": 0.76,
        "relationship_density": 6.8
      },
      "examples": [
        {
          "concept_id": 1503297,
          "concept_name": "Metformin",
          "concept_code": "6809",
          "vocabulary_id": "RxNorm",
          "concept_class_id": "Ingredient"
        },
        {
          "concept_id": 1308216,
          "concept_name": "Lisinopril 10 MG Oral Tablet",
          "concept_code": "314077",
          "vocabulary_id": "RxNorm",
          "concept_class_id": "Clinical Drug"
        }
      ],
      "valid_start_date": "1970-01-01T00:00:00Z",
      "valid_end_date": "2099-12-31T00:00:00Z"
    },
    {
      "domain_id": "Procedure",
      "domain_name": "Procedure",
      "domain_concept_id": 10,
      "description": "Medical procedures, surgical interventions, diagnostic tests, and therapeutic interventions",
      "category": "clinical",
      "concept_count": 456789,
      "standard_concept_count": 234561,
      "primary_vocabularies": ["SNOMED", "ICD10PCS", "HCPCS"],
      "color_hex": "#2ecc71",
      "icon_name": "stethoscope",
      "statistics": {
        "total_concepts": 456789,
        "vocabulary_distribution": {
          "SNOMED": 198765,
          "ICD10PCS": 76543,
          "HCPCS": 45678,
          "Others": 48149
        },
        "usage_frequency": 0.64,
        "relationship_density": 3.9
      },
      "examples": [
        {
          "concept_id": 4273391,
          "concept_name": "Coronary artery bypass graft",
          "concept_code": "232717009",
          "vocabulary_id": "SNOMED",
          "concept_class_id": "Procedure"
        }
      ],
      "valid_start_date": "1970-01-01T00:00:00Z",
      "valid_end_date": "2099-12-31T00:00:00Z"
    }
    ],
    "domain_summary": {
    "total_domains": 23,
    "total_concepts_across_domains": 3456789,
    "most_common_vocabularies": ["SNOMED", "RxNorm", "ICD10CM", "LOINC"],
    "domain_categories": {
      "clinical": 15,
      "administrative": 4,
      "derived": 3,
      "metadata": 1
      }
    }
  },
  "meta": {
    "request_id": "req_domains_789",
    "timestamp": "2024-12-22T10:30:00Z",
    "vocab_release": "2025.2"
  }
}

​
Usage Examples

​
All Domains

Get all available domains: 
const res = await fetch('/v1/domains', {
  headers: {
    'Authorization': 'Bearer YOUR_API_KEY'
  }
});

if (!res.ok) {
  throw new Error(`HTTP ${res.status}: ${res.statusText}`);
}

const data = await res.json();
const domains = data.domains;

​
Domains with Concept Counts

Get domains with concept statistics: 
const res = await fetch('/v1/domains?include_concept_counts=true&sort_by=concept_count&sort_order=desc', {
  headers: {
    'Authorization': 'Bearer YOUR_API_KEY'
  }
});

if (!res.ok) {
  throw new Error(`HTTP ${res.status}: ${res.statusText}`);
}

const data = await res.json();
const domainsWithCounts = data?.domains || [];

​
Clinical Domains Only

Filter to clinical domains: 
const clinicalDomains = domains.filter(d => d.category === 'clinical');

​
Domains for Specific Vocabularies

const detailedRes = await fetch('/v1/domains?include_concept_counts=true&include_statistics=true&include_examples=true', {
  headers: { 'Authorization': 'Bearer YOUR_API_KEY' }
});
const { domains: detailedDomains } = await detailedRes.json();

// Get domains for specific vocabularies
const res = await fetch('/v1/domains?vocabulary_ids=SNOMED&include_statistics=true', {
  headers: {
    'Authorization': 'Bearer YOUR_API_KEY'
  }
});

if (!res.ok) {
  throw new Error(`HTTP ${res.status}: ${res.statusText}`);
}

const data = await res.json();
const snomedDomains = data.domains;

​
Detailed Domain Analysis

Get comprehensive domain information: 
const response = await fetch('/v1/domains?include_concept_counts=true&include_statistics=true&include_examples=true', {
  headers: { 'Authorization': 'Bearer YOUR_API_KEY' }
});
if (!response.ok) throw new Error(`HTTP ${response.status}: ${response.statusText}`);
const { domains: detailedDomains } = await response.json();

​
Notes

  • Domains provide the highest level of semantic categorization in OMOP
  • The most commonly used clinical domains are Condition, Drug, and Procedure
  • Some concepts may appear in multiple domains through different vocabularies
  • Domain concept counts include both standard and non-standard concepts unless filtered
  • Usage frequency indicates how often domains are queried in typical applications
  • Color codes and icons are suggestions for consistent UI representation across applications
  • Administrative domains include things like Provider, Care Site, and Payer
  • Derived domains contain computed or inferred concepts
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