README

A PHP SDK for the WHO ICD API. Provides typed access to ICD-11 Foundation, ICD-11 Linearization (MMS), and ICD-10 endpoints with built-in OAuth2 authentication and Laravel support.

Requirements

• PHP 8.2+
• A WHO ICD API account (register here)

Installation

composer require ayarse/who-icd-api-php

Concepts

If you're new to ICD, here's a quick rundown of the terminology:

ICD (International Classification of Diseases) is the WHO's global standard for classifying diseases and health conditions. Every time a doctor records a diagnosis, files an insurance claim, or a country reports death statistics, they're using ICD codes. Think of it as the universal language hospitals and governments use to talk about diseases.

ICD-10 vs ICD-11 are two generations of this system. ICD-10 has been around since 1990 and is still widely used. ICD-11 is the current version (adopted 2019) and is far more detailed. This SDK supports both.

Foundation is ICD-11's master knowledge base - a giant graph of every disease, symptom, and health concept the WHO recognizes. A single disease can appear under multiple parent categories here (e.g. "Tuberculosis of the lung" lives under both "Infectious diseases" and "Respiratory diseases"). You can't directly code with it, but it's the source of truth everything else is derived from.

Linearization is a practical, codeable view extracted from the Foundation. Since real-world coding systems need each disease in exactly one place (not multiple), a linearization "flattens" the Foundation into a single-parent hierarchy and assigns codes. MMS (Mortality and Morbidity Statistics) is the main linearization - it's what people usually mean when they say "ICD-11 codes". You'll pass 'mms' as the linearization name for most use cases.

Postcoordination is ICD-11's way of adding detail to a code without needing thousands of pre-defined combinations. Instead of a separate code for "Cholera caused by Vibrio cholerae O1", you take the base code 1A00 (Cholera) and combine it with an infectious agent code using & (e.g. 1A00&XN62R). The API can parse, validate, and simplify these combinations.

Release ID (e.g. 2026-01, 2024-01) is a version identifier. The WHO publishes updated releases of ICD-11 periodically. Most endpoints require you to specify which release you're querying against.

DORIS is the WHO's system for automatically determining the underlying cause of death from a death certificate. You feed it the certificate fields and it applies the WHO's selection rules to pick the single underlying cause. COEDIT is the related certificate-checking system that validates the coding.

Autocoding is the NLP feature - you give it free text like "acute appendicitis" and it returns the best matching ICD code (DB10.0).

Quick Start

use WhoIcd\WhoIcdConnector;

$icd = new WhoIcdConnector(
    clientId: 'your-client-id',
    clientSecret: 'your-client-secret',
);

// Search for a disease
$response = $icd->linearization()->search('2026-01', 'mms', q: 'diabetes');
$results = $response->json();

// Auto-code free text to an ICD-11 code
$response = $icd->linearization()->autoCode('2026-01', 'mms', searchText: 'acute appendicitis');
$data = $response->json();
echo $data['theCode']; // DB10.0

// Get an entity by ID
$response = $icd->linearization()->getEntity('2026-01', 'mms', '257068234');
$data = $response->json();
echo $data['code']; // 1A00 (Cholera)

Laravel Integration

The package auto-registers via Laravel's package discovery. Add your credentials to .env:

WHO_ICD_CLIENT_ID=your-client-id
WHO_ICD_CLIENT_SECRET=your-client-secret
WHO_ICD_LANGUAGE=en
WHO_ICD_API_VERSION=v2

Publish the config file:

php artisan vendor:publish --tag=who-icd-config

Then use dependency injection or the facade:

use WhoIcd\WhoIcdConnector;

// Dependency injection
public function search(WhoIcdConnector $icd)
{
    $response = $icd->linearization()->search('2026-01', 'mms', q: 'cholera');
    return $response->json();
}

// Facade
use WhoIcd\Facades\WhoIcd;

$response = WhoIcd::foundation()->search(q: 'cholera');

Configuration

API Reference

The SDK is organized into three resource groups accessible from the connector:

Foundation ($icd->foundation())

The ICD-11 Foundation is the complete ontological layer containing every health entity in a multi-parent graph.

// Get top-level Foundation entities
$icd->foundation()->get();

// Get a specific Foundation entity with optional ancestor/descendant inclusion
$icd->foundation()->getEntity('455013390', include: 'ancestor,descendant');

// Search the Foundation
$icd->foundation()->search(
    q: 'cholera',
    useFlexisearch: true,       // Flexible matching (partial words)
    chapterFilter: '01;02',     // Limit to specific chapters
    highlightingEnabled: false,  // Disable HTML highlight tags
);

// Auto-code free text against the Foundation
$icd->foundation()->autoCode(searchText: 'diabetes mellitus');

Linearization ($icd->linearization())

Linearizations are single-parent, code-bearing classifications derived from the Foundation. The primary linearization is MMS (Mortality and Morbidity Statistics).

// List available releases
$icd->linearization()->getReleases('mms');

// Get a specific release (chapters list)
$icd->linearization()->get('2026-01', 'mms');

// Get a coded entity
$icd->linearization()->getEntity('2026-01', 'mms', '257068234');

// Get a residual entity (other/unspecified)
$icd->linearization()->getResidualEntity('2026-01', 'mms', '257068234', 'unspecified');

// Search with full options
$icd->linearization()->search(
    releaseId: '2026-01',
    linearizationName: 'mms',
    q: 'malaria',
    medicalCodingMode: true,         // Only return coded entities
    includeKeywordResult: true,      // Word completion suggestions
    subtreeFilterUsesFoundationDescendants: false,
);

// Auto-code free text to an ICD-11 code
$icd->linearization()->autoCode('2026-01', 'mms', searchText: 'acute appendicitis');

// Look up a code or postcoordinated combination
$icd->linearization()->getCodeInfo('2026-01', 'mms', '1A00');

// Describe a code/URI - can simplify postcoordinated combos
$icd->linearization()->describe('2026-01', 'mms', code: 'GC08&XN6P4', simplify: true);

// Map a Foundation entity to its linearization code
$icd->linearization()->lookup(
    '2026-01', 'mms',
    foundationUri: 'http://id.who.int/icd/entity/257068234',
);

// Death certificate checking (COEDIT)
$icd->linearization()->certificateCheck(
    releaseId: '2026-01',
    sex: 1,
    estimatedAge: 'P65Y',
    causeOfDeathCodeA: 'BA41.Z',
    causeOfDeathCodeB: 'BA80',
);

// Underlying cause of death detection (DORIS)
$icd->linearization()->underlyingCauseOfDeathDetection(
    releaseId: '2026-01',
    sex: 2,
    causeOfDeathCodeA: 'BA41.Z',
);

ICD-10 ($icd->icd10())

Legacy ICD-10 access (browse only, no search).

// List available ICD-10 releases
$icd->icd10()->getReleases();

// Get a specific release (chapters)
$icd->icd10()->getRelease('2019');

// Get an ICD-10 entity
$icd->icd10()->getEntity('2019', 'A00');

// Check which releases contain a specific code
$icd->icd10()->getAvailableReleasesForEntity('A00');

Data Transfer Objects

All API responses can be hydrated into typed DTOs via ::fromArray():

use WhoIcd\Data\LinearizationEntity;
use WhoIcd\Data\ISearchResult;
use WhoIcd\Data\AutoCodingSearchResult;

// Entity
$response = $icd->linearization()->getEntity('2026-01', 'mms', '257068234');
$entity = LinearizationEntity::fromArray($response->json());
echo $entity->code;            // "1A00"
echo $entity->title->value;   // "Cholera"

// Search results
$response = $icd->linearization()->search('2026-01', 'mms', q: 'malaria');
$results = ISearchResult::fromArray($response->json());
foreach ($results->destinationEntities as $entity) {
    echo "{$entity->theCode}: {$entity->title}\n";
}

// Auto-coding
$response = $icd->linearization()->autoCode('2026-01', 'mms', searchText: 'heart attack');
$result = AutoCodingSearchResult::fromArray($response->json());
echo $result->theCode;       // "BA41.Z"
echo $result->matchScore;    // 1.0

Available DTOs

Language Support

The API supports 20+ languages. Set the language when constructing the connector:

// Spanish
$icd = new WhoIcdConnector($clientId, $clientSecret, language: 'es');

// Chinese
$icd = new WhoIcdConnector($clientId, $clientSecret, language: 'zh');

Or in Laravel via .env:

WHO_ICD_LANGUAGE=fr

Use Cases

• Hospital EMR systems - Code diagnoses at point of care
• Insurance & billing - Validate and translate diagnosis codes
• Mortality statistics - Automate cause-of-death coding from death certificates
• Medical research - Traverse disease hierarchies and relationships
• Clinical decision support - Look up definitions, diagnostic criteria, coding notes
• ICD-10 to ICD-11 migration - Map legacy codes via Foundation lookup
• Multilingual health apps - Serve medical terminology in any supported language

License

MIT

Links

• WHO ICD API Documentation
• ICD-11 Browser
• Saloon Documentation
• Register for API Access