Risk on lung transplant waitlist found higher for sarcoidosis patients
US study calls for reconsideration of criteria for waitlist priority grouping
Death rates while waiting for a lung transplant are disproportionally higher among people with pulmonary sarcoidosis than for those with other lung disorders, a U.S. study shows.
“Our research shows that further consideration needs to be given to how we classify patients with sarcoidosis and how we calculate their risk of dying on the waitlist,” researchers wrote in the study “Sarcoidosis lung transplantation waitlist mortality, a national registry database study,” published in ERJ Open Research.
Sarcoidosis is characterized by inflammatory cell clumps that can form in virtually any organ of the body, but most commonly in the lungs — then referred to as pulmonary sarcoidosis. When lung disease becomes advanced, a lung transplant may be warranted.
Lung Allocation Score used since 2005 to prioritize patients for lung transplants
In the U.S., a system called the Lung Allocation Score, or LAS, has been used since 2005 to prioritize patients for lung transplants. This system was designed based mainly on data from fairly common lung diseases like idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD).
After the system was implemented, the number of patients with these illnesses who died while awaiting lung transplant dropped dramatically. But despite these well-established benefits for IPF and COPD, the LAS may not be as effective for prioritizing lung transplant in people with pulmonary sarcoidosis, evidence suggests.
Currently, the LAS divides pulmonary sarcoidosis patients based on the presence of high blood pressure in the lungs, referred to as pulmonary hypertension, which is a well-established risk factor for worse lung disease.
Those with pulmonary hypertension are placed in LAS group D, a more severe category that includes most IPF patients. Those without pulmonary hypertension are instead put in LAS group A, a milder category that includes most people with COPD.
Now, a team of researchers in the U.S. compared mortality outcomes across the U.S. for adults awaiting lung transplant due to different diseases but who were in the same LAS group. The team had previously shown that waitlist mortality at a single U.S. center was higher in lung sarcoidosis patients than among those with IPF or COPD.
“We hypothesize that at a national level, sarcoidosis patients have a higher transplant waitlist mortality than patients in the same grouping,” the researchers wrote.
Our research shows that further consideration needs to be given to how we classify patients with sarcoidosis and how we calculate their risk of dying on the waitlist.
Researchers identified patients with lung diseases in LAS groups A and D
Using data from a national transplant registry after the LAS was implemented in 2005, the team identified 385 pulmonary sarcoidosis patients without pulmonary hypertension and 7,081 COPD patients who were all assigned to LAS group A.
They also identified 642 people with pulmonary sarcoidosis and pulmonary hypertension and 10,639 IPF patients who were placed in LAS group D.
Compared with people with other lung diseases, those with pulmonary sarcoidosis tended to be younger, were more often Black, and less likely to be smokers.
Among patients in LAS group A, the total mortality rate while on the waitlist was significantly higher for those with pulmonary sarcoidosis than among those with COPD (14.3% vs. 9.8%). Similarly, in LAS group D, pulmonary sarcoidosis patients showed a significantly higher mortality rate than those with IPF (17.3% vs. 14.8%).
Statistical analyses showed that the risk of waitlist mortality was nearly two times higher for people with pulmonary sarcoidosis in group A relative to those with COPD. This was independent of other influencing factors including age, sex, race, measures of lung function, and height — which can affect the likelihood of finding a matching lung donor.
“It is important to note that the variables that affect organ matching and procurement such as patient height, maximum candidate donor height, blood type and surgical preference for double lungs did not have a statistically significant impact on risk of waitlist mortality,” the researchers wrote.
Study suggests LAS may need to include other co-occurring health conditions
Among patients in group D, statistical models accounting for these influencing factors showed that the risk of on-waitlist mortality was actually higher in IPF patients relative to those with pulmonary sarcoidosis.
However, further analyses showed this difference was attributable to a higher rate of IPF deaths within the first two months of being placed on the waitlist. At later times, the mortality rate was comparable between IPF and pulmonary sarcoidosis patients in group D.
Collectively, these findings add to prior work suggesting that, while the LAS has had a clear positive impact on outcomes for common lung diseases like IPF and COPD, “for less common indications of lung transplantation there appears to be a need to revisit some assumptions that were necessary during the development of the LAS,” the researchers wrote.
The scientists speculated that additional factors like other co-occurring health conditions beyond pulmonary hypertension may need to be included in the LAS system to adequately prioritize pulmonary sarcoidosis patients. They stressed a need for further study into these potential factors.
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