How ICD-10 Codes Map to an HCC / RAF Score (and Why the Same Code Set Yields Different Scores)

If you're building anything that touches Medicare Advantage risk adjustment, sooner or later you hit this question:

"How do ICD-10 codes map to an HCC / RAF score?"

The short answer that trips most people up: ICD-10-CM codes don't carry a RAF weight individually. There's a pipeline between the diagnosis code and the number, and skipping a step gives you a wrong score. Here's the whole chain.

The Pipeline

1. ICD-10 → HCC