Define Hierarchical Condition Category and explain why hierarchy matters in risk adjustment.

• A. An HCC is a method for categorizing patients by age and gender to adjust risk.
• B. An HCC is a category that aggregates multiple unrelated diagnoses into separate risk factors.
• C. An HCC is a condition category that aggregates related diagnoses into a single risk factor; hierarchy means if multiple diagnoses map to related HCCs, only the most severe (highest-weight) HCC is used for risk calculation.
• D. An HCC is a billing code that directly sets payment amounts.

Answer: (C)