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Cost Inputs Technical Report

IXA-001 Budget Impact Model

Document Version: 1.0 Date: February 2026 Author: HEOR Technical Documentation Team Status: Final

1. Executive Summary

This technical report documents all cost inputs used in the IXA-001 Budget Impact Model (BIM). The model incorporates drug acquisition costs, clinical event costs, monitoring costs, and indirect costs to project the total budget impact of IXA-001 introduction over a 5-year time horizon.

2. Drug Acquisition Costs

2.1 IXA-001 Pricing

Parameter Value Source
Monthly Cost (US) $500 Manufacturer pricing
Annual Cost (US) $6,000 Calculated
WAC vs. Net 85% net-to-gross Industry average

2.2 Comparator Drug Costs

Drug Monthly Cost Annual Cost Source
Spironolactone 25-50mg $15 $180 RedBook AWP
Eplerenone 25-50mg $100 $1,200 RedBook AWP
Other MRAs (average) $50 $600 Weighted average

2.3 Drug Cost Differentials

Comparison Monthly Δ Annual Δ Multiplier
IXA-001 vs. Spironolactone +$485 +$5,820 33.3×
IXA-001 vs. Eplerenone +$400 +$4,800 5.0×
IXA-001 vs. Other MRAs +$450 +$5,400 10.0×

3. Clinical Event Costs

3.1 Cardiovascular Event Costs

Event Acute Cost Year 1 Follow-up Ongoing Annual Source
Myocardial Infarction $25,000 $8,500 $4,200 HCUP, CMS
Stroke (Ischemic) $22,000 $12,000 $8,500 HCUP
Stroke (Hemorrhagic) $35,000 $18,000 $12,000 HCUP
Heart Failure Hospitalization $18,000 $6,500 $5,200 HCUP
Atrial Fibrillation (new onset) $8,500 $4,200 $3,800 CMS

3.2 Renal Event Costs

Event Acute Cost Ongoing Annual Source
CKD Stage 3 diagnosis $2,500 $3,500 USRDS
CKD Stage 4 diagnosis $4,500 $8,500 USRDS
ESRD (dialysis initiation) $35,000 $90,000 USRDS 2023
Kidney transplant $150,000 $25,000 OPTN

3.3 Adverse Event Costs

Event Per-Episode Cost Source
Hyperkalemia (hospitalized) $12,500 HCUP
Hyperkalemia (outpatient) $850 Medicare claims
Gynecomastia (treatment) $350 CPT codes
AKI (acute kidney injury) $18,000 HCUP

4. Monitoring and Management Costs

4.1 Routine Monitoring

Service Frequency Unit Cost Annual Cost
Office visit (established) 4/year $125 $500
Basic metabolic panel 4/year $35 $140
Potassium level 4/year $15 $60
eGFR/Creatinine 4/year $25 $100
Blood pressure monitoring 12/year $25 $300
Total Annual Monitoring - - $1,100

4.2 IXA-001 Specific Monitoring

Service Frequency Unit Cost Annual Cost
PAC/PRA ratio (initial) 1× $185 $185
Aldosterone level 2/year $95 $190
Additional potassium 2/year $15 $30
IXA-001 Incremental - - $405

4.3 Total Monitoring Costs by Treatment

Treatment Routine Incremental Total
Spironolactone $1,100 $0 $1,100
Eplerenone $1,100 $150 $1,250
IXA-001 $1,100 $405 $1,505

5. Country-Specific Cost Adjustments

5.1 Cost Multipliers

Country Drug Cost Mult. Event Cost Mult. Monitoring Mult.
US 1.00 1.00 1.00
UK 0.45 0.55 0.60
DE 0.65 0.70 0.75
FR 0.55 0.65 0.70
IT 0.50 0.60 0.65
ES 0.45 0.55 0.60

5.2 Currency Conversion

Country Currency Exchange Rate (to USD)
US USD 1.00
UK GBP 1.25
DE, FR, IT, ES EUR 1.08

5.3 Example: UK Cost Calculation

IXA-001 Annual (UK) = $6,000 × 0.45 / 1.25 = £2,160
MI Acute (UK) = $25,000 × 0.55 / 1.25 = £11,000

6. Cost Offsets from Event Prevention

6.1 Event Rate Reduction

Event IXA-001 RRR Events Prevented (per 1000) Cost Offset
MI 30% 4.5 $150,750
Stroke 40% 3.2 $91,200
HF Hospitalization 50% 8.7 $182,700
ESRD 55% 1.2 $150,000
AF 60% 12.5 $162,500

6.2 Net Cost Calculation

Net Cost = Drug Cost + Monitoring - Event Cost Offsets

Per Patient (Year 1):
IXA-001: $6,000 + $1,505 - $1,875 = $5,630
Spiro:   $180 + $1,100 - $0 = $1,280
Incremental: $4,350/patient

7. Indirect Costs (Societal Perspective)

7.1 Productivity Loss by Event

Event Work Days Lost Wage/Day Productivity Loss
MI (acute) 45 $280 $12,600
MI (ongoing) 10/year $280 $2,800/year
Stroke 90 $280 $25,200
HF Hospitalization 21 $280 $5,880
ESRD (dialysis) 156/year $280 $43,680/year

7.2 Caregiver Burden

Event Caregiver Hours/Week Weeks Hourly Rate Total
Stroke (first year) 25 52 $15 $19,500
ESRD (ongoing) 10 52 $15 $7,800/year
HF (ongoing) 8 52 $15 $6,240/year

7.3 Total Societal Cost per Event

Event Direct Medical Indirect Caregiver Total Societal
MI $33,500 $15,400 $0 $48,900
Stroke $34,000 $25,200 $19,500 $78,700
HF $23,200 $5,880 $6,240 $35,320
ESRD $125,000 $43,680 $7,800 $176,480

8. Budget Impact Calculation

8.1 Incremental Drug Cost

Incremental Drug Cost = Σ (N_patients × IXA_share × ΔCost_drug)

Year 1 (Moderate Scenario):
= 3,760,742 × 0.05 × ($6,000 - $180 × 0.50 - $1,200 × 0.30 - $600 × 0.15)
= 188,037 × $5,400
= $1,015 million

8.2 Total Budget Impact Formula

Total BI = Drug BI + Monitoring BI - Event Cost Offsets

Where:
Drug BI = Σ_years (N_IXA × Cost_IXA - N_displaced × Cost_displaced)
Monitoring BI = Σ_years (N_IXA × ΔMonitoring)
Event Offsets = Σ_events (Events_prevented × Cost_event)

8.3 5-Year Budget Impact Summary (US, Moderate)

Year Drug Cost Monitoring Event Offsets Net BI
1 $1,015M $76M -$145M $946M
2 $2,436M $182M -$348M $2,270M
3 $4,071M $304M -$581M $3,794M
4 $5,494M $410M -$784M $5,120M
5 $6,528M $488M -$932M $6,084M

9. Implementation Details

9.1 CostInputs Class

@dataclass
class CostInputs:
    """Cost inputs for BIM calculations."""
    # Drug costs (annual)
    ixa_001_cost: float = 6000.0
    spironolactone_cost: float = 180.0
    eplerenone_cost: float = 1200.0
    other_mra_cost: float = 600.0

    # Monitoring costs (annual)
    routine_monitoring: float = 1100.0
    ixa_incremental_monitoring: float = 405.0

    # Event costs (acute + year 1)
    mi_cost: float = 33500.0
    stroke_cost: float = 34000.0
    hf_cost: float = 23200.0
    esrd_cost: float = 125000.0
    af_cost: float = 12700.0
    hyperkalemia_cost: float = 12500.0

9.2 EventCosts Class

@dataclass
class EventCosts:
    """Detailed event costs for budget impact calculations."""
    mi_acute: float = 25000.0
    mi_followup: float = 8500.0
    mi_ongoing: float = 4200.0

    stroke_acute: float = 22000.0
    stroke_followup: float = 12000.0
    stroke_ongoing: float = 8500.0

    hf_acute: float = 18000.0
    hf_followup: float = 6500.0
    hf_ongoing: float = 5200.0

    esrd_initiation: float = 35000.0
    esrd_annual: float = 90000.0

    af_acute: float = 8500.0
    af_ongoing: float = 3800.0

9.3 Code References

  • Implementation: src/bim/inputs.py:CostInputs, EventCosts
  • Calculation: src/bim/calculator.py:BIMCalculator._calculate_costs

10. Data Sources

10.1 Drug Cost Sources

Source Data Type Year
RedBook AWP drug prices 2024
CMS ASP Medicare reimbursement 2024
NADAC Pharmacy acquisition 2024
Manufacturer IXA-001 pricing 2026

10.2 Medical Cost Sources

Source Data Type Year
HCUP NIS Inpatient costs 2022
MEPS Outpatient costs 2022
USRDS ESRD costs 2023
Medicare Claims Procedure costs 2023

10.3 Indirect Cost Sources

Source Data Type Year
BLS Wage data 2024
AARP Caregiver survey 2023
Published literature Productivity loss Various

11. PSA Distributions

11.1 Drug Costs

Parameter Distribution Mean SE α/β
IXA-001 cost Fixed $6,000 - -
Spiro cost Gamma $180 $36 25, 7.2
Eplerenone cost Gamma $1,200 $240 25, 48

11.2 Event Costs

Parameter Distribution Mean SE α/β
MI cost Gamma $33,500 $6,700 25, 1,340
Stroke cost Gamma $34,000 $6,800 25, 1,360
HF cost Gamma $23,200 $4,640 25, 928
ESRD cost Gamma $125,000 $25,000 25, 5,000

12. Limitations

  1. Price uncertainty: IXA-001 pricing subject to negotiation and contracting
  2. Regional variation: Costs vary significantly by payer and region
  3. Inflation: Medical cost inflation not dynamically modeled
  4. Indirect costs: Productivity estimates based on average wages
  5. Event attribution: All events attributed to hypertension may overestimate offsets

13. References

  1. Agency for Healthcare Research and Quality. HCUP National Inpatient Sample. 2022.

  2. United States Renal Data System. 2023 Annual Data Report. NIDDK.

  3. Centers for Medicare & Medicaid Services. Medicare Provider Payment Data. 2024.

  4. Medi-Span RedBook. Drug Pricing Reference. 2024.

  5. Medical Expenditure Panel Survey. Agency for Healthcare Research and Quality. 2022.

  6. Bureau of Labor Statistics. Occupational Employment and Wage Statistics. 2024.

  7. AARP Public Policy Institute. Valuing the Invaluable: 2023 Update.

Document Control:

  • Version 1.0 - Initial release (February 2026)
  • Reviewed by: HEOR Technical Lead
  • Approved for HTA submission