What is the Lung Allocation Score?

Penn Medicine

The lung allocation score (LAS) is an important factor in determining priority for receiving a lung transplant when a donor lung becomes available. The system determines the order of everyone awaiting a lung transplant by their lung allocation scores, blood type and geographic distance between the candidates and the hospital where the lung donor is located. Age also plays a role because lungs from pediatric and adolescent donors are offered first to pediatric and adolescent transplant candidates before they are offered to adults.

The lung allocation system uses medical information specific to each lung transplant candidate. This information includes lab values, test results and disease diagnosis and is used to calculate an LAS from 0 to 100. The score represents an estimate of the severity of every candidate’s illness and the chance of success following a lung transplant. All candidates are placed in order for compatible lung offers according to their score: A candidate with a higher lung allocation score receives higher priority for a lung offer when a compatible lung becomes available.

The supply of donor lungs is limited. The OPTN designed this allocation system to more effectively use the limited number of available donor lungs as well as reduce the number of deaths among people waiting for a transplant. Prior to this system, transplant candidates received donor lungs based on the amount of time they had been on the waitlist. The lung allocation score system is based on scientific data regarding lung transplantation and by drawing on prior experience with many types of people with lung diseases, and offers donor lungs to candidates according to their medical characteristics.

Johns Hopkins Medicine
Developed by the United Network for Organ Sharing (UNOS), the Lung Allocation Score tells the patient (12 years and older) how close they are to transplantation on the waiting list. Ranging from zero (less ill) to 100 (gravely ill), patients with higher scores receive priority for transplantation over those with lower scores. The score can be reassessed by additional testing at any point if a patient’s clinical status changes. The lung allocation score is based on the following tests:

- Forced vital capacity - a lung function test that measures the maximum amount of air you can breathe out after you breathe in as deeply as possible.
- Pulmonary artery pressure - the pressure the heart must generate to pump blood through the lungs.
- Oxygen at rest - the amount of oxygen needed by a patient at rest to maintain adequate oxygen levels in the blood.
- Carbon dioxide levels
- Age
- Body mass index - BMI is a ratio of a patient’s weight to height that, when interpreted with other medical test results, helps to evaluate health status.
- Insulin dependent diabetes - Diabetes may be a predictor of health status in some patients with lung disease.
- Functional status - The New York Heart Association classifications measure effects that lung disease may have on a patient’s function in everyday life.
- Creatinine - Creatinine levels are a measure of kidney function.
- Six-minute walk distance - In the six-minute walk test, a patient is asked to walk as far as s/he can in six minutes. The distance walked is a measure of functional status.
- Ventilator use - The use of a ventilator to assist breathing may be a measure of disease severity and may affect success after transplant.
- Pulmonary capillary wedge pressure - PCW or "Wedge Pressure" is the pressure blood returning to the heart from the lungs must overcome.
- Diagnosis - urgency among patients needing a transplant and success after transplant vary among patients with different lung diseases due to the specific progression of the particular disease.

Continue Learning about Lung Transplant

Lung Transplant

If your breathing problem is so severe that your life is threatened, a lung transplant may be considered. Donor lungs usually come from someone who is deceased. The operation lasts 4 to 12 hours, and in some cases may include a do...

nor heart as well. There is a several week hospital stay followed by close follow-up. Modern matching techniques and drug therapy have significantly reduced problems with organ rejection, although this is still a possibility. After the operation, patients usually report an improved quality of life. Overall, 83% of lung transplant patients survive the first year, and about 60% survive three years.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.