Lung Composite Allocation Score (CAS) for candidates age 12 and older

Step 1: Waiting list urgency	The transplant center enters the factors in part 1 below on the UNet website. A Cox proportional hazards model has been used to derive an estimate of the expected number of days a candidate would live without a transplant during an additional year on the waitlist. The patient receives up to 25 points in a non-linear manner (Number of points = [25^(1-expected_survival/365) – 1]/24).
Step 2: Expected post-transplant survival	The transplant center enters the factors in part 2 below on the UNet website. A Cox proportional hazards model has been used to derive an estimate of the number of days a recipient would be expected to live during the first five year post-transplant. The patient receives up to 25 points linearly based on this is the post-transplant survival measure (Number of points = 25 * estimated_survival/1826).
Step 3: Biologic compatibility	The patient's biologic compatibility is determined non-linearly based on 1) Calculated Panel Reactive Antibodies (CPRA), 2) blood type, and 3) height (5 points each, 15 total points)
Step 4: Patient access	Additional points are given to certain groups of patients to increase their access to lung transplantation. Pediatric patients receive 20 points and prior living organ donors reveive 5 points.
Step 5: Placement efficiency	The final 10 points are allocated based on distance between the donor hospital and transplant centerto account for travel costs, coordination costs, risk of travel to personnel and organs, as well as potentially detrimental effects of organ ischemia associated with transporting lungs long distances.
Part 1 – Waiting list urgency measure:
Age Serum bilirubin Body mass index (BMI) Continuous mechanical ventilation Serum creatinine Diagnosis* Functional status^¶ Supplemental O₂ required at rest pCO₂^Δ Pulmonary artery systolic pressure 6-minute walk distance
Part 2 – Post-transplant survival measure:
Age Serum creatinine Cardiac index at rest Continuous mechanical ventilation Diagnosis* Functional status^¶ 6-minute walk distance

* Diagnosis groups:

Group A: Chronic obstructive pulmonary disease (COPD), alpha-1-antitrypsin, emphysema, lymphangioleiomyomatosis, bronchiectasis, sarcoidosis with a mean pulmonary artery pressure (MPAP) ≤30 mmHg.
Group B: Pulmonary hypertension (idiopathic pulmonary arterial hypertension [IPAH], Eisenmenger syndrome, etc).
Group C: Cystic fibrosis, immunodeficiency disorders (eg, hypogammaglobulinemia).
Group D: Idiopathic pulmonary fibrosis (IPF), other causes of pulmonary fibrosis, other idiopathic interstitial pneumonias, connective tissue disease-associated interstitial lung disease, hypersensitivity pneumonitis, sarcoidosis with MPAP >30 mmHg, bronchiolitis, lung retransplant, and other rare disorders.

The post-transplant survival measure also separately factors in the following specific diagnoses: bronchiectasis, obliterative bronchiolitis, constrictive bronchiolitis, sarcoidosis ± MPAP >30.

The waiting list urgency measure also separately factors in the following specific diagnoses: bronchiectasis, other causes of pulmonary fibrosis (including COVID-19), and sarcoidosis ± MPAP >30.

¶ Functional status is a binary assessment of whether the patient requires assistance with activities of daily living.

Δ pCO₂ may be taken from arterial, capillary or venous measurement. If venous, 6 mmHg will be subtracted to produce an equivalent arterial value. There is also an adjustment for an increase of greater than 15% over less than 6 months.

Adapted from: Organ Procurement and Transplantation Network (OPTN) Policies. Available at: https://optn.transplant.hrsa.gov/media/eavh5bf3/optn_policies.pdf (Accessed May 07, 2023). More information about the LAS calculator can be found at: https://optn.transplant.hrsa.gov/data/allocation-calculators/lung-cas-calculator/ (Accessed May 07, 2023).

Graphic 59818 Version 4.0

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Lung Composite Allocation Score (CAS) for candidates age 12 and older