MS-DRG API

Look up Medicare Severity Diagnosis Related Groups for inpatient hospital payment classification.

Overview

MS-DRG (Medicare Severity Diagnosis Related Groups) is the patient classification system used by CMS for inpatient hospital payment under the Inpatient Prospective Payment System (IPPS). Each DRG groups clinically similar diagnoses and procedures with comparable resource utilization. FHIRfly provides fast lookups against the current MS-DRG definitions, including relative weights and length-of-stay data.

Endpoints

Method	Path	Description
GET	`/v1/msdrg/:code`	Single MS-DRG lookup
POST	`/v1/msdrg/_batch`	Batch lookup (up to 100)
GET	`/v1/msdrg/shapes`	List available response shapes

Single Lookup

Look up MS-DRG 470 (Major Joint Replacement)

Request

Node.js

const response = await fetch(
  "https://api.fhirfly.io/v1/msdrg/470",
  {
    method: "GET",
    headers: {
    "x-api-key": "YOUR_API_KEY",
  }
  }
);

const data = await response.json();
console.log(data);

Response

JSON

{
  "data": {
    "drg_code": "470",
    "title": "MAJOR HIP AND KNEE JOINT REPLACEMENT OR REATTACHMENT OF LOWER EXTREMITY WITHOUT MCC",
    "mdc": "08",
    "type": "SURG",
    "weight": 1.7394,
    "geometric_mean_los": 1.8,
    "arithmetic_mean_los": 2.1
  },
  "meta": {
    "legal": {
      "license": "public_domain",
      "attribution_required": false,
      "source_name": "CMS MS-DRG"
    }
  }
}

Common MS-DRGs

DRG	Title	MDC	Type
470	Major Hip and Knee Joint Replacement w/o MCC	08	SURG
871	Septicemia or Severe Sepsis w/o MV >96 Hours w/ MCC	18	MED
291	Heart Failure and Shock w/ MCC	05	MED
065	Intracranial Hemorrhage or Cerebral Infarction w/ MCC	01	MED
193	Simple Pneumonia and Pleurisy w/ MCC	04	MED
392	Esophagitis, Gastroenteritis w/o MCC	06	MED

Batch Lookup

Look up multiple MS-DRGs in a single request (up to 100):

Look up multiple MS-DRGs

Request

Node.js

const response = await fetch(
  "https://api.fhirfly.io/v1/msdrg/_batch",
  {
    method: "POST",
    headers: {
    "x-api-key": "YOUR_API_KEY",
    "Content-Type": "application/json",
  },
    body: JSON.stringify({
    "codes": [
      "470",
      "871",
      "291"
    ]
  })
  }
);

const data = await response.json();
console.log(data);

Response

JSON

{
  "count": 3,
  "results": [
    {
      "input": "470",
      "code": "470",
      "status": "ok",
      "data": {
        "drg_code": "470",
        "title": "MAJOR HIP AND KNEE JOINT REPLACEMENT OR REATTACHMENT OF LOWER EXTREMITY WITHOUT MCC",
        "mdc": "08",
        "type": "SURG"
      }
    },
    {
      "input": "871",
      "code": "871",
      "status": "ok",
      "data": {
        "drg_code": "871",
        "title": "SEPTICEMIA OR SEVERE SEPSIS WITHOUT MV >96 HOURS WITH MCC",
        "mdc": "18",
        "type": "MED"
      }
    },
    {
      "input": "291",
      "code": "291",
      "status": "ok",
      "data": {
        "drg_code": "291",
        "title": "HEART FAILURE AND SHOCK WITH MCC",
        "mdc": "05",
        "type": "MED"
      }
    }
  ],
  "meta": {
    "legal": {
      "license": "public_domain"
    }
  }
}

Batch with `shape=full`

When using shape=full on batch requests, the response includes meta.source with provenance information:

POST /v1/msdrg/_batch?shape=full

{
  "count": 3,
  "results": [
    {
      "input": "470",
      "code": "470",
      "status": "ok",
      "data": {
        "drg_code": "470",
        "title": "MAJOR HIP AND KNEE JOINT REPLACEMENT OR REATTACHMENT OF LOWER EXTREMITY WITHOUT MCC",
        "mdc": "08",
        "type": "SURG",
        "weight": 1.7394,
        "geometric_mean_los": 1.8,
        "arithmetic_mean_los": 2.1
      }
    }
  ],
  "meta": {
    "source": {
      "name": "CMS MS-DRG",
      "url": "https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software",
      "version": "FY2026",
      "fhirfly_updated_at": "2026-03-01T03:00:00Z"
    },
    "legal": {
      "license": "public_domain",
      "attribution_required": false
    }
  }
}

Response Shapes

Control the level of detail in responses with the shape query parameter:

Shape	Description
`compact`	DRG code, title, MDC, type
`standard`	+ weight, geometric/arithmetic mean LOS (default)
`full`	+ ingest metadata, provenance

# Minimal data
GET /v1/msdrg/470?shape=compact

# Standard data (default)
GET /v1/msdrg/470?shape=standard

# Full data with provenance
GET /v1/msdrg/470?shape=full

See Response Shapes for field details.

Required Scopes

msdrg.read - Single and batch lookups
msdrg.search - Search MS-DRG codes