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mz-drg

High-performance CMS claim processing tools written in Zig with Python bindings.

License: MIT Zig Python Docs

mz-drg provides open-source reimplementations of CMS tools:

  • MS-DRG Grouper — assigns Diagnosis Related Groups based on diagnoses, procedures, and demographics
  • Medicare Code Editor (MCE) — validates ICD diagnosis and procedure codes against CMS edit rules
  • ICD-10 Converter — maps codes between fiscal year versions using CMS conversion tables

All are written in Zig, callable from Python, and validated against the CMS reference Java implementations with a 100% match rate on 50,000+ claims.

⚡ Why mz-drg?

The official CMS tools are Java applications. While accurate, they come with practical limitations:

  • JVM Overhead — Requires seconds for JVM warmup and significant heap memory.
  • Throughput — Java performance is typically ~500 claims/sec; mz-drg reaches 11,000+ claims/sec on similar hardware.
  • Minimal Footprint — Uses memory-mapped LMDB data with zero-copy access.
  • Embedding — Simple C ABI enables integration with Python (ctypes), Rust, C++, and more.

🚀 Quick example

import msdrg

# MS-DRG grouping
with msdrg.MsdrgGrouper() as g:
    result = g.group({
        "version": 431, "age": 65, "sex": 0, "discharge_status": 1,
        "pdx": {"code": "I5020"}, "sdx": [{"code": "E1165"}], "procedures": []
    })
    print(result["final_drg"])  # 293

# MCE validation
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"

# ICD-10 code conversion
with msdrg.IcdConverter() as conv:
    new_code = conv.convert_dx("B880", source_year=2025, target_year=2026)
    print(new_code)  # "B8801"

📖 What's next?