The calculation requires applying the CMS-HCC hierarchy rules. Both "diabetes with nephropathy" and "diabetes with retinopathy" fall into the same disease category (HCC 18, Diabetes with Chronic Complications). When multiple diagnoses within a hierarchical category are present, only the single HCC for that category is counted once in the risk score calculation. Therefore, the score is the sum of the demographic factor (0.332), the single HCC for diabetes with complications (0.166), and the HCC for atrial fibrillation (0.299).

Calculation: 0.332 + 0.166 + 0.299 = 0.797.

A. 0.932: This result is incorrect; it appears to be a miscalculation, possibly by incorrectly adding one of the diabetes HCCs twice. The correct sum is 0.797.

C. 1.418: This result is incorrect and does not follow the HCC model's calculation rules, likely representing an arbitrary or flawed summation.

D. 0.678: This result is incorrect. It may come from omitting one of the valid HCC weights or a simple arithmetic error in the summation.

1. Centers for Medicare & Medicaid Services (CMS). (2023). CMS-HCC Model V28 Software/ICD-10 Mappings. The documentation for the risk adjustment model software explicitly details the application of hierarchies where only one HCC from a related family of conditions contributes to the score.

2. Centers for Medicare & Medicaid Services (CMS). (2022). Risk Adjustment 101. Module 4: "Calculating the Risk Score," pp. 15-17. This training document explains the concept of hierarchies in the CMS-HCC model. Available at CMS.gov.