Modifications to the Lung Allocation Score (LAS) system were implemented on February 19, 2015. Among the revisions are policy changes that have occurred over the course of many years, resulting from numerous proposals. Here's a summary of the changes.
New Data Variables
The new LAS calculation is largely based on variables transplant programs already report to the OPTN for lung candidates. Transplant programs can already report cardiac index (CI) and central venous pressure (CVP) to the OPTN for their lung candidates in WaitlistSM. Beginning on February 19, these variables are now factored into the LAS calculation. Additionally, the system allows the entry of CVP data obtained through means other than a heart catheterization.
Total bilirubin (bilirubin) is the only new variable added to the calculation that was not previously collected in the system. Bilirubin is collected and stored serially, like PCO2. You can add the candidate’s current bilirubin value, as well as historical values.
Serum creatinine is also collected and stored serially. Like bilirubin and PCO2, transplant programs can report current and historical values for serum creatinine.
While entry of historic values for the serial data (PCO2, bilirubin, and serum creatinine) is optional, these values may impact a candidate’s LAS.
Missing, Expired, or Below Threshold Data
Previously, if data were missing or expired for either the candidate’s functional status or assisted ventilation fields, the candidate’s LAS was set to zero. In the new system, policy default values for these variables are used in the calculation when the data are missing or expired.
In the LAS system, lung diagnoses are divided into four diagnosis categories: A) obstructive lung disease; B) pulmonary vascular disease; C) cystic fibrosis; and D) restrictive lung diseases. The list of lung diseases and their diagnosis groupings are largely the same as the previous LAS system, but more diagnoses have been added.
Added to Group B
• Pulmonary capillary hemangiomatosis
Added to Group D
- ABCA3 transporter mutation
- Idiopathic interstitial pneumonia (IIP), with at least one or more of the following disease entities:
- Acute interstitial pneumonia
- Desquamative interstitial pneumonia
- Nonspecific interstitial pneumonia
- Respiratory bronchiolitis-associated interstitial lung disease
- Pulmonary lymphangiectasia (PL)
- Secondary pulmonary fibrosis (specify cause)
- Surfactant protein C mutation