Myelin

Myelin is a comprehensive Python toolkit for interacting with key components of the US healthcare reimbursement system. It provides a unified, developer-friendly interface to official CMS (Centers for Medicare & Medicaid Services) software, enabling programmatic access to:

• MS-DRG Grouper: Assigns inpatient claims to Diagnosis-Related Groups (DRGs) for payment determination.
• HHA Grouper (HHAG): Groups home health claims based on clinical and functional status, using OASIS data.
• IRF Grouper (IRFG): Groups inpatient rehabilitation facility claims.
• MCE Editor: Validates inpatient claims against the Medicare Code Editor (MCE) to ensure clinical coherence.
• IOCE Editor: Processes outpatient claims through the Integrated Outpatient Code Editor (IOCE) to assign Ambulatory Payment Classifications (APCs).
• IPPS Pricer: Calculates reimbursement for inpatient claims under the Inpatient Prospective Payment System (IPPS).
• OPPS Pricer: Calculates reimbursement for outpatient claims under the Outpatient Prospective Payment System (OPPS).
• IPF Pricer: Calculates reimbursement for inpatient claims under the Inpatient Psychiatric Facility Prospective Payment System (IPF PPS).
• IRF Pricer: Calculates reimbursement for inpatient rehabilitation facility claims.
• LTCH Pricer: Calculates reimbursement for long-term care hospital claims.
• SNF Pricer: Calculates reimbursement for skilled nursing facility claims.
• HHA Pricer: Calculates reimbursement for home health claims.
• Hospice Pricer: Calculates reimbursement for hospice claims.
• ESRD Pricer: Calculates reimbursement for End-Stage Renal Disease claims.
• FQHC Pricer: Calculates reimbursement for Federally Qualified Health Center claims.

Built on top of the official Java-based CMS tools, Myelin uses jpype to create a seamless bridge to Python, allowing developers, analysts, and researchers to integrate these critical healthcare components into their workflows for automation, analytics, and research.

What is Myelin?

In the complex world of healthcare reimbursement, claims are processed through a series of steps to determine how much a provider should be paid. Myelin simplifies this process by providing a single, easy-to-use Python library that handles the most important of these steps:

• Grouping: Assigning a standardized code (like a DRG or APC) that categorizes the patient's episode of care.
• Editing: Checking the claim for errors or inconsistencies based on clinical and coding rules.
• Pricing: Calculating the final payment amount based on the assigned group and other factors.

By wrapping the official CMS software, Myelin ensures that you are using the same logic as Medicare and other major payers, providing a high degree of accuracy and reliability.

Features

• Unified Interface: A single, consistent API for interacting with multiple CMS tools.
• Flexible Claim Construction: Easily create and modify claims using Pydantic data models.
• Support for Multiple Editors and Groupers: Includes interfaces for the MCE (inpatient), IOCE (outpatient), HHA (home health), and IRF (inpatient rehabilitation) grouper/editors.
• Comprehensive Pricer Suite: Full-featured pricers for IPPS, OPPS, IPF, IRF, LTCH, SNF, HHA, Hospice, ESRD, and FQHC.
• UB-04 PDF Read/Write: Convert Claim objects to filled CMS-1450/UB-04 PDFs and read filled UB-04 PDFs back into Claim objects.
• Extensible: The underlying architecture makes it easy to add new components or customize existing ones.
• Example Scripts: Get up and running quickly with a comprehensive set of examples in the example.py file.

Requirements

• Python 3.10+
• Java (JRE/JDK, Java 17+ is recommended)
• JPype1 (Python-Java bridge)
• DRG, MCE, IOCE, and Pricer Java JAR files (provided in the jars/ directory or downloadable)

Installation

Install from PyPI:

pip install myelin-pps

Optional extras are available for UB-04 PDF read/write support and the Excel exporters:

pip install myelin-pps[pdf]
pip install myelin-pps[excel]
pip install myelin-pps[all]

Or install from source:

1. Clone this repository:

   git clone https://github.com/LibrePPS/myelin.git
   cd Myelin
   

2. Install Python dependencies:

   pip install -r requirements.txt
   

   To use UB-04 PDF read/write support, install the optional PDF dependencies:

   pip install .[pdf]
   

   To use the to_excel() / to_excel_bytes() exporters, install the optional Excel dependencies:

   pip install .[excel]
   

   Or install everything at once with the all extra:

   pip install .[all]
   

   or, if you use uv:

   uv sync
   

   with PDF support:

   uv sync --extra pdf
   

   with Excel support:

   uv sync --extra excel
   

   or all extras:

   uv sync --extra all
   

   dev dependencies:

   uv sync --group dev
   

3. Ensure Java is installed and available in your PATH.
   • Check with: java -version

Testing

pytest tests/

Linting & Formatting

Before commiting run ruff tooling.

Linter:

ruff check .

Autofix what you can, manually fix the remaining errors.

Import Sorting and Formatter:

ruff check --select I --fix
ruff format

Setup

Myelin is designed to handle the setup and configuration of the environment for you. By default, it will:

• Create the jars/ and data/ directories if they don't exist.
• Download the latest CMS grouper and editor JARs.
• Download the latest CMS pricer JARs.
• Create and populate the necessary SQLite databases for the pricers.

To get started, simply instantiate the Myelin class:

from myelin import Myelin

myelin = Myelin(build_jar_dirs=True, build_db=True)

Usage

The example.py script provides a comprehensive set of examples for using all the features of myelin. Here's a brief overview of how to use each component through the Myelin class:

uv run example.py

MS-DRG Grouper

The DrgClient is used to process inpatient claims and assign a DRG.

from myelin import Myelin
from myelin.helpers.test_examples import claim_example

myelin = Myelin(build_jar_dirs=True, build_db=True)

claim = claim_example()
drg_output = myelin.drg_client.process(claim)
print(drg_output.model_dump_json(indent=2))

HHA Grouper (HHAG)

The HhagClient is used to process home health claims. This grouper has a special requirement for OASIS assessment data, which can be provided in oasis object class on the Claim object.

The following variables are supported within the oasis class:

• Risk flags (boolean/int): fall_risk, weight_loss, multiple_hospital_stays, multiple_ed_visits, mental_behavior_risk, compliance_risk, five_or_more_meds, exhaustion, other_risk, none_of_above.
• Functional status (string codes): grooming, dress_upper, dress_lower, bathing, toileting, transferring, ambulation.

If the "oasis" key is not provided, a set of defaults will be used.

from myelin import Myelin
from myelin.helpers.test_examples import claim_example
from datetime import datetime

myelin = Myelin(build_jar_dirs=True, build_db=True)

claim = claim_example()
claim.from_date = datetime(2025, 1, 1)
claim.thru_date = datetime(2025, 1, 31)

# Add OASIS data
claim.oasis_assessment = OasisAssessment()
claim.oasis_assessment.fall_risk = 1
claim.oasis_assessment.multiple_hospital_stays = 1
claim.oasis_assessment.grooming = "1"

hhag_output = myelin.hhag_client.process(claim)
print(hhag_output.model_dump_json(indent=2))

IRF Grouper (IRFG)

The IrfgClient is used to process inpatient rehabilitation facility claims.

from myelin import Myelin
from myelin.helpers.test_examples import claim_example

myelin = Myelin(build_jar_dirs=True, build_db=True)

claim = claim_example()
irfg_output = myelin.irfg_client.process(claim)
print(irfg_output.model_dump_json(indent=2))

MCE Editor

The MceClient is used to validate inpatient claims against the MCE edits.

from myelin import Myelin
from myelin.helpers.test_examples import claim_example

myelin = Myelin(build_jar_dirs=True, build_db=True)

claim = claim_example()
mce_output = myelin.mce_client.process(claim)
print(mce_output.model_dump_json(indent=2))

IOCE Editor

The IoceClient is used to process outpatient claims through the IOCE editor.

from myelin import Myelin
from myelin.helpers.test_examples import opps_claim_example

myelin = Myelin(build_jar_dirs=True, build_db=True)

opps_claim = opps_claim_example()
ioce_output = myelin.ioce_client.process(opps_claim)
print(ioce_output.model_dump_json(indent=2))

Inpatient & Long-Term Care Pricers

This suite of pricers calculates reimbursement for various inpatient and long-term care settings. The IPPS, IPF, and LTCH pricers require the output from the DrgClient, while the SNF pricer operates directly on the claim.

• IppsClient: For standard inpatient claims (IPPS).
• IpfClient: For inpatient psychiatric facility (IPF) claims.
• LtchClient: For long-term care hospital (LTCH) claims.
• SnfClient: For skilled nursing facility (SNF) claims.
• IrfClient: For inpatient rehabilitation facility (IRF) claims.

from myelin import Myelin
from myelin.helpers.test_examples import claim_example
from datetime import datetime

myelin = Myelin(build_jar_dirs=True, build_db=True)

claim = claim_example()
drg_output = myelin.drg_client.process(claim)
irfg_output = myelin.irfg_client.process(claim)

# IPPS Pricer
ipps_output = myelin.ipps_client.process(claim, drg_output)
print("IPPS Output:", ipps_output.model_dump_json(indent=2))

# IPF Pricer
ipf_output = myelin.ipf_client.process(claim, drg_output)
print("IPF Output:", ipf_output.model_dump_json(indent=2))

# LTCH Pricer
# LTCH may require specific provider IDs or other claim modifications
ltch_claim = claim_example()
ltch_claim.billing_provider.other_id = "012006"
ltch_drg_output = myelin.drg_client.process(ltch_claim)
ltch_output = myelin.ltch_client.process(ltch_claim, ltch_drg_output)
print("LTCH Output:", ltch_output.model_dump_json(indent=2))

# SNF Pricer
# SNF claims have specific requirements for bill type, DX, etc.
snf_claim = claim_example()
snf_claim.admit_date = datetime(2025, 1, 1)
snf_claim.from_date = datetime(2025, 1, 1)
snf_claim.thru_date = datetime(2025, 1, 20)
snf_claim.bill_type = "327"
snf_claim.principal_dx.code = "B20"
snf_output = myelin.snf_client.process(snf_claim)
print("SNF Output:", snf_output.model_dump_json(indent=2))

# IRF Pricer
irf_output = myelin.irf_client.process(claim, irfg_output)
print("IRF Output:", irf_output.model_dump_json(indent=2))

Outpatient Pricers

• OppsClient: For standard outpatient claims (OPPS).
• HhaClient: For home health agency (HHA) claims.
• EsrdClient: For end-stage renal disease (ESRD) claims.
• FqhcClient: For federally qualified health center (FQHC) claims.

OPPS Pricer

The OppsClient is used to calculate the reimbursement for an outpatient claim. It requires the output from the IoceClient.

from myelin import Myelin
from myelin.helpers.test_examples import opps_claim_example

myelin = Myelin(build_jar_dirs=True, build_db=True)

opps_claim = opps_claim_example()
ioce_output = myelin.ioce_client.process(opps_claim)
opps_output = myelin.opps_client.process(opps_claim, ioce_output)
print(opps_output.model_dump_json(indent=2))

Hospice Pricer

The HospiceClient calculates reimbursement for hospice claims. It operates directly on the claim object.

from myelin import Myelin
from myelin.helpers.test_examples import claim_example
from myelin.input import LineItem, ValueCode
from datetime import datetime

myelin = Myelin(build_jar_dirs=True, build_db=True)

claim = claim_example()
claim.bill_type = "812"
claim.patient_status = "40"
claim.value_codes.append(ValueCode(code="61", amount=35300.00))
claim.thru_date = datetime(2025, 7, 10)
claim.lines.append(
    LineItem(
        hcpcs="Q5001",
        revenue_code="0651",
        service_date=datetime(2025, 7, 1),
        units=9
    )
)

hospice_output = myelin.hospice_client.process(claim)
print(hospice_output.model_dump_json(indent=2))

UB-04 PDF Read/Write

Myelin can generate a filled CMS-1450/UB-04 PDF from a Claim and can also parse a filled UB-04 PDF back into a Claim. Currently only one PDF is supported but we may expand this in the future.

from myelin.input.claim import Claim
from myelin.helpers.ub04_pdf import write_ub04_calibration_pdf
from myelin.helpers.claim_examples import claim_example

claim = claim_example()

# Write a filled UB-04 PDF and also get the bytes in memory
pdf_bytes = claim.to_ub04_pdf("sample-ub04.pdf")

# Read a filled UB-04 PDF back into a Claim
parsed_claim = Claim.from_ub04_pdf("sample-ub04.pdf")

print(parsed_claim.model_dump_json(indent=2, exclude_none=True))

You can also generate the PDF entirely in memory:

pdf_bytes = claim.to_ub04_pdf()

To generate a calibration PDF that labels every mapped field position on the bundled template:

write_ub04_calibration_pdf("ub04-calibration.pdf")

UB-04 PDF support requires the optional pdf extra.

Excel Export

Every MyelinOutput can be exported to a multi-sheet Excel workbook for sharing with business users. Each pricer / editor / grouper result is written to its own sheet, with a Summary sheet up front containing the high-level metrics from every module.

from myelin import Myelin, MyelinOutput
from myelin.helpers.claim_examples import claim_example

with Myelin() as myelin:
    claim = claim_example()
    results = myelin.process(claim)
    results.to_excel("output.xlsx", claim=claim)

    # Or grab the bytes directly (e.g. for an HTTP response)
    excel_bytes = results.to_excel_bytes(claim=claim)

Excel export support requires the optional excel extra (pip install myelin-pps[excel]).

Project Structure

• myelin/client.py – Main class for interacting with the CMS tools and example usage.
• msdrg/ – MS-DRG Grouper client and output models
• hhag/ – HHA Grouper client and output models
• irfg/ – IRF Grouper client and output models
• mce/ – MCE Editor client and output models
• ioce/ – IOCE Editor client and output models
• pricers/ – Clients for all pricers (IPPS, OPPS, IPF, IRF, LTCH, SNF, HHA, Hospice, ESRD, FQHC)
• input/ – Pydantic models for claims and related data
• helpers/ – Utility scripts, including the CMS downloader
• jars/ – Directory for Java JAR files (not tracked in git)
• data/ – Directory for SQLite databases (not tracked in git)

Troubleshooting

• JVM Not Started: Ensure Java is installed and the JAR path is correct.
• Missing JARs: The Myelin class should handle this automatically. If not, ensure the jars/ directory is writable.
• JPype Errors: Make sure JPype1 is installed and matches your Python version.
• Pricer Errors: Ensure you have created the databases by running Myelin(build_db=True).

License

MIT License. See LICENSE.