Adding cystic-fibrosis-specific variables to the lung allocation score allows for more accurate identification of patients who are likely to benefit from a lung transplant, according to a new study.
The study, titled “Effect of Including Important Clinical Variables on Accuracy of the Lung Allocation Score for Cystic Fibrosis and Chronic Obstructive Pulmonary Disease,” was published in the American Journal of Respiratory and Critical Care Medicine.
The lung allocation score (LAS) was implemented in 2005 to prioritize patients waiting for a lung transplant in the United States. The score is used to quantify how urgently a patient needs a lung transplant — for whatever reason — as well as how much benefit the procedure is expected to have (i.e. how much it would prolong survival).
In theory, people who are sicker get higher scores and, thus, earlier transplants as organs become available.
However, researchers believe that this score misses some important clinical factors when it comes to prioritizing people with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD) who are awaiting a transplant.
Compared with other types of patients who end up on the transplant waiting list, people with CF “are younger, often have more infections, and multiple organs that are affected by their disease,” Carli Lehr, MD, MS, a physician at Cleveland Clinic and co-author of the study, said in a press release.
For the study, the researchers merged data from two databases: the U.S. Scientific Registry of Transplant Recipients (SRTR), and the Cystic Fibrosis Foundation (CFF) Patient Registry. The data included 9,043 people who were older than 11 years and on the lung transplant waiting list (1,020 of whom had CF), and 6,110 people who received lung transplants (including 677 people with CF) from January 2011 to December 2014.
Because the CFF registry records all clinical data for nearly every CF patient in the U.S., and the SRTR includes data for patients as soon as they are put on the lung transplant waitlist, the study was able to cover patients’ clinical histories over the course of their lives.
The researchers analyzed the data and identified variables missed by the LAS that influenced patients’ likelihood of dying while on the waiting list. These included infections due to a group of bacteria called Burkholderia, coughing up blood (hemoptysis), and being hospitalized for 29 to 42 days.
Additionally, a pulmonary exacerbation time of 15–28 days increased the likelihood of death after a transplant.
Furthermore, decreases in FEV1 — the amount of air a person can exhale in one second — were a significant predictor of mortality risk for COPD and CF patients on the waitlist.
“We believe the database we used more accurately identifies candidates likely to benefit the most from a transplant,” said Maryam Valapour, MD, director of Lung Transplant Outcomes in Cleveland Clinic’s Respiratory Institute and the study’s co-author.
According to the team, “adding CF-specific variables improved discrimination among waitlisted CF candidates, and benefitted COPD candidates.”