Methods, Evidence & Scientific Governance

1. Purpose and Intended Use

The Sustainable Kidney Care Planner (SKCC) is a deterministic planning model built to help hospital renal programs, nephrologists, operations managers, and sustainability leads evaluate the environmental, financial, and operational feasibility of sustainable kidney care interventions.

Intended Use: SKCC supports exploratory capital planning, operational screening, and draft business-case preparation for maintenance hemodialysis (HD) and hemodiafiltration (HDF) facilities. It provides standardized physical mass-balance calculations for water conservation, acid concentrate handling, packaging avoidance, waste diversion, and electricity-related emissions.

Regulatory & Clinical Boundaries:

• SKCC is not clinical decision support (CDS) software. It is intended for operational and program planning and does not provide patient-specific diagnosis, prescribing, or treatment recommendations.
• SKCC does not prescribe or recommend medical therapy for individual patients.
• Clinical initiatives (such as dialysate flow rate reduction) represent aggregate unit-level operational modeling and must be implemented exclusively under physician prescription, validated adequacy protocols (Kt/V monitoring), and local clinical governance.
• Public default outputs are preliminary site-dependent estimates. Financial figures must be verified against actual facility utility tariffs, commercial contracts, and vendor tenders before capital submission.

2. Model Population and Care-Setting Scope

The model baseline targets in-centre hemodialysis units and hospital satellite units in Canada:

• Standard Patient Treatment Schedule: 3 treatments per week, 52 weeks per year (156 treatments per active patient annually).
• Default Session Duration: 4.0 hours (240 minutes) per session.
• Station Utilization: Scalable station configurations (e.g., 6, 12, 20, 24, 30 stations) operating 6 days per week across 2 patient shifts per day.
• Geographic Calibration: Provincial grid emission intensities, electricity prices, combined water/wastewater tariffs, and healthcare purchasing structures across all 13 Canadian provinces and territories.

3. Calculation Year and Geography

The current model reporting basis is Calendar Year 2026 in Canadian Dollars (CAD):

• Ontario Grid Factor: Environment and Climate Change Canada (ECCC) 2026 consumption intensity factor of 59 g CO₂e / kWh (Table 5.1 Electricity Consumption Intensity, Federal GHG Offset Credit System Regulations). Historical 2023–2024 (30 g) and 2025 (38 g) factors are documented in the registry but are not silently applied to 2026 estimates.
• Provincial Specificity: When another province (e.g., British Columbia, Alberta) is selected, provincial ECCC consumption factors and published local utility tariffs (e.g., Hydro-Québec, BC Hydro, Toronto Water, EPCOR) are dynamically populated.

4. Financial Perspective & Economic Standards

Financial analyses are conducted strictly from the perspective of the Hospital Operating and Capital Budget / Regional Renal Program:

• CADTH / CDA-AMC Reference Discount Rate: In accordance with Canadian Agency for Drugs and Technologies in Health (CADTH / CDA-AMC) Guidelines for the Economic Evaluation of Health Technologies: Canada (4th Edition, 2017), multi-year reference evaluations use a discount rate of 1.5% annually for costs and benefits occurring beyond one year. Sensitivity analyses at 0% and 3% are supported.
• Hospital Capital Hurdle Rates: When a hospital or regional health authority evaluates a business case using an internal hurdle rate (e.g., 4% or 5%), this parameter is explicitly documented as a local business-case assumption and is not mislabeled as a CADTH requirement.
• Evaluation Horizon: Configurable based on physical asset useful life (typically 10 years for piping and RO water treatment assets, 5 years for machine upgrades, or 1 to 3 years for operational workflow adjustments). CADTH does not mandate a universal 10-year horizon.
• Societal Carbon Valuation: Societal carbon benefit values are reported separately in physical units (tonnes CO₂e) and are never blended into hospital cash savings.

5. Environmental System Boundary

Physical resource accounting enforces clean separation of mass and energy streams:

6. Core Physical Equations & Worked Mass Balances

6.1 Central Acid Delivery Systems (CDS)

Eliminates single-use 4.5 L acid jugs in favor of bulk storage loops. Avoids residual chemical dregs (33% wastage in individual jugs) and jug tare weight (0.18 kg jug + 0.04 kg cap):

6.2 Online Priming & Rinseback

Substitutes disposable 1L–2L saline bags with machine-generated ultrapure dialysate:

6.3 Biohazard Waste Stream Segregation

Separates non-contaminated outer plastic wrap and cartons from blood-contact disposables. Conserves mass between streams:

6.4 Dialysate Flow Rate (DFR) Optimization: Worked Mass Balance

Individualizes dialysate flow from baseline 500 mL/min to 400 mL/min over a 4-hour (240 min) treatment session for eligible patients:

6.5 Reverse Osmosis (RO) Water Optimization

Upgrades baseline single-pass RO recovery or recaptures RO reject water:

7. Initiative Interaction & Double-Count Prevention

When multiple technical initiatives are combined in a scenario, physical interactions are handled strictly to prevent double-counting:

• DFR × RO Interaction: DFR optimization reduces the total permeate volume demanded from the water room. Consequently, municipal feed water savings from RO reject recovery are calculated on the net remaining permeate volume, preventing both initiatives from claiming the same water reduction twice.
• Online Priming × Biohazard Waste Interaction: Online priming completely eliminates saline infusion bags at the source (0.08 kg). When biohazard waste segregation is active simultaneously, the baseline divertible plastic pool is reduced by 0.08 kg so saline bags are not claimed as diverted waste.
• Multi-Criteria Self-Assessment Reconciliation: Multiple assessment criteria (e.g., jug elimination and jug disposal) that map to Central Acid Delivery draw from one unified pool of financial savings. When CDS is selected in planning, its savings are subtracted from remaining opportunity exactly once.

8. Evidence Classification & Grading System

Every parameter, formula, and assumption in the SKCC registry is assigned one of seven explicit evidence categories:

9. Local vs. Illustrative Inputs

The SKCC calculation differentiates between parameters that must be confirmed locally and standard benchmark defaults:

• Must Be Confirmed Locally: Number of dialysis stations, active patient census, local utility tariffs (water, sewer, electricity), local biohazard disposal contracts, contractor installation quotes for CDS loops or RO retrofits, and local patient clinical eligibility protocols.
• Governed Default Benchmarks: RO recovery baseline (70%), acid jug residual volume (1.75 L dregs in 4.5 L jugs), packaging dry weight breakdown (0.27 kg clean wrap/cartons), and ECCC 2026 Ontario consumption grid intensity (59 g CO₂e / kWh).

10. Uncertainty and Scenario Analysis

To prevent unwarranted reliance on single-point estimates, the calculation engine runs sensitivity analyses across three tiers:

• Conservative Tier: Lower-bound utility tariffs, lower waste diversion efficiency (50%), higher capital costs (+15%), and lower acid dregs wastage (1.25 L).
• Expected / Base Tier: Governed baseline parameters reflecting peer-reviewed and official reference values.
• Optimistic Tier: Higher utility tariffs, optimal diversion rates (75%), and streamlined capital implementation.

11. Clinical Balancing and Safety Considerations

Environmental sustainability changes must never compromise patient safety, treatment adequacy, or infection control:

• Dialysate Flow Rate Reduction: Dialysate flow reduction to 400 mL/min must be individually prescribed. Routine Kt/V adequacy monitoring and monthly single-pool urea clearance surveillance are mandatory. Patients with large body surface area or marginal vascular access must be evaluated clinically.
• Regulated Biohazard Segregation: Waste segregation must follow applicable provincial requirements and local IPAC/waste-management policy. The ORN sustainable kidney-care self-assessment identifies diversion of eligible non-saturated dialysis tubing from biomedical waste as an opportunity, while sharps, clotted circuits, cytotoxic materials, and items meeting local biomedical-waste criteria remain in the regulated stream. Confirm the local classification pathway before using financial or environmental estimates. Dual-receptacle separation must clearly distinguish clean outer packaging from regulated clinical waste.
• Water Quality & Disinfection: Any modification to machine or loop heat/chemical disinfection must be approved by Biomedical Engineering and Infection Control. Regular microbiological testing (endotoxin < 0.25 EU/mL and total viable count < 100 CFU/mL per ISO 23500) is non-negotiable.
• Online Priming & Fluid Purity: Machine online infusate substitution requires dual microbiological ultrafilters and strict filter lifecycle changeout protocols.

12. Model Versioning and Change Control

SKCC model calculations are version-controlled and governed under strict change control:

• Canonical Engine: Shipped engine module in public/calc-engine.js is the single source of calculation truth.
• Governance Registry: Assumptions registry version 2.0.0; model version model_2026_09_v2.
• Zero-Drift Policy: All modifications are evaluated in a sandboxed VM against governed Ontario and British Columbia benchmark test cases. The release gate requires 0.00% drift.

13. Validation Performed

The following verification and validation steps have been executed:

• Automated Test Suite: 118 unit and integration tests covering RBAC security, boundary conditions, CSV escaping, and mathematical edge cases.
• Deterministic Reference Comparison: Continuous validation against Ontario 20-station baseline and BC 6-station baseline with zero tolerance for unintended variance.
• Cloud Infrastructure Verification: 17 live cloud verification gates executed against Azure Table Storage and Azure Static Web Apps.

14. Validation Not Yet Performed

Users and review committees should note the following validations remain pending:

• Prospective External Clinical Validation: Multi-centre prospective clinical trials tracking patient outcomes across Canadian renal programs adopting these pathways have not yet been completed.
• Sub-Metered Facility Audits: Direct sub-metered water and electrical monitoring across multiple hospital building configurations is pending local pilot completion.

15. Known Limitations

• Plumbing & Space Constraints: Central acid loop retrofits require ceiling or subfloor piping distribution; structural or architectural renovation costs vary significantly by site.
• Time-of-Use Electric Tariffs: Realizing off-peak disinfection electrical savings requires smart interval utility metering and participation in commercial TOU pricing programs.
• Scope 3 Upstream Disclosures: Supply chain embodied carbon relies on international life-cycle assessment (LCA) literature; Canadian domestic polymer manufacturing factors may exhibit localized variation.

16. Complete Verified References

All cited publications, official inventories, and technical standards have been audited and verified: