MCE Overview¶

The Medicare Code Editor (MCE) validates ICD diagnosis and procedure codes against CMS edit rules. It checks for invalid codes, sex conflicts, age conflicts, unacceptable PDX codes, and more.

How it works¶

The MCE is a linear validation pipeline:

graph LR
    A[Input Claim] --> B[Code Validation]
    B --> C[Attribute Loading]
    C --> D[Edit Rule Evaluation]
    D --> E[Output]

    B -->|"Check codes exist<br>in CMS master"| C
    C -->|"Load sex, age,<br>code attributes"| D
    D -->|"Apply ~35<br>edit rules"| E

1. Code validation — checks codes exist in the CMS master for the discharge date
2. Attribute loading — loads code attributes (sex restrictions, age groups, etc.)
3. Edit rule evaluation — applies ~35 edit rules
4. Output — returns edit type and per-edit counts

Basic usage¶

import msdrg

with msdrg.MceEditor() as mce:
    result = mce.edit({
        "discharge_date": 20250101,
        "age": 65,
        "sex": 0,
        "discharge_status": 1,
        "pdx": {"code": "I5020"},
        "sdx": [],
        "procedures": []
    })

print(result["edit_type"])  # "NONE" or "PREPAYMENT", etc.

Or use the convenience helper:

mce_claim = msdrg.create_mce_input(
    discharge_date=20250101, age=65, sex=0, discharge_status=1,
    pdx="I5020", sdx=["E1165"]
)
result = mce.edit(mce_claim)

Validation¶

The MCE is validated against the CMS Java MCE 2.0 v43.1 with a 100% match rate on 49,996 test claims.

Thread safety¶

The MCE context is immutable after initialization and safe to share across threads. Each call to edit() is thread-safe.