LAS System May Fail to Identify Sarcoidosis Patients at Urgent Need of Lung Transplant, Study Finds
The current scoring system used to assess the urgency of lung transplants, called LAS (lung allocation score), fails to predict the risk of death in people with sarcoidosis, a single center study suggests.
The study “Mortality for sarcoidosis patients on the transplant wait list in the Lung Allocation Score era: Experience from a high volume center” was published in the journal Respiratory Medicine.
Over 90% of sarcoidosis patients have impaired lung function, but symptom progression to a risk of death is seen in less than 10% of the cases. About 2.5% to 3.5% of referrals for a possible lung transplant are people with advanced pulmonary sarcoidosis, its researchers noted.
LAS is a measure used to set priorities on lung transplant waiting lists. Established in 2005 by the Organ Procurement Transplantation Network (OPTN), it uses a score from zero to 100 that takes into account the level of lung impairment, and not the time on the list.
Mortality in pulmonary sarcoidosis was determined before the establishment of LAS. But, “during the initial development of the LAS, sarcoidosis data was too sparse to develop disease-specific prognostic factors and therefore [this population] was grouped with COPD (termed Group A) or idiopathic pulmonary fibrosis (IPF),” the study said.
Researchers at the Lewis Katz School of Medicine at Temple University, in Philadelphia, looked at how well LAS predicts lung function decline and mortality risk in sarcoidosis patients.
The team reviewed data from 28 sarcoidosis patients referred for double lung transplant at Temple University Hospital between March 2012 and February 2019.
Results showed that 22 patients survived the transplant, and six died while on a waiting list. This corresponds to a mortality rate of 18.2%. Among the six patients, one died of respiratory failure, one due to ventricular arrhythmia, and one experienced respiratory distress at home. The remaining three patients had no conclusive cause of death since no autopsy was performed.
When researchers compared mortality rates to people diagnosed with chronic lung diseases at the same institute, namely IPF and chronic obstructive pulmonary disease (COPD), they saw that these rates were lower: 12.3% among IPF patients, and 8.7% for COPD patients during the study period.
Median survival rate of sarcoidosis patients who underwent transplant was 70 months, similar to that of other indications.
The LAS scores from patients who survived the transplant showed no significant differences to those who died on the waiting list, with both having a score of 41.
However, lung function markers of advanced lung scarring were associated with a higher death risk on transplant list. Specifically, a low diffusion capacity of the lungs for carbon monoxide (DLCO, 21% or less), and an elevated Composite Physiologic Index (CPI, 67.7% or more) were significant predictors of death among transplant patients.
“Our analysis suggests severe interstitial disease at baseline predicts mortality in this population, and is not necessarily captured by the LAS system. We found that markers of advanced fibrotic disease burden, such as low DLCO and high CPI, were statistical predictors of death, as has been previously observed in non-transplant population,” the researchers wrote.
The levels of bilirubin (the result of the breakdown of red blood cells) had the highest predictive value for death among patients on the transplant list — bilirubin of 0.35 mg/dL or below was the cut-off value to identify those at risk of death with 100% sensitivity.
Overall, the team concluded that “sarcoidosis patients on the lung transplant wait list experience a high mortality, even exceeding mortality for IPF patients at our center. The listing LAS and change in LAS did not predict death.”
Given the results, the researchers suggested that “reconsideration of current referral and transplant candidacy listing recommendations for advanced pulmonary sarcoidosis may be warranted.”