Still holding their breath: Mortality on lung transplant wait list remains high for some

Aug 24, 2009

Mortality remains high among patients with pulmonary arterial hypertension awaiting lung transplant, despite changes to the allocation system that were designed to reduce mortality and increase the equitable distribution of donor organs, according to new research out of University of California San Francisco.

The study is reported in the September 1 issue of the , published by the American Thoracic Society.

Until just a few years ago, the amount of time that a given patient had been on the waiting list was the only factor in determining his or her priority, but in 2005, a new allocation system based on a "lung allocation score" (LAS), was implemented. LAS is determined in part by the patient's functional status, exercise capacity, lung function, hemodynamic data and the need for ventilatory support.

Overall, mortality on the lung transplant waiting list has fallen as a result of the changes, especially among those with chronic obstructive pulmonary disease (COPD), idiopathic (IPF) and (CF); patients with idiopathic pulmonary arterial hypertension (IPAH), however, make up only a small minority of lung-transplant candidates, and therefore little is known about whether and how they have benefited from the changes to lung allocation protocols.

"Most people will agree that the LAS has improved organ allocation for most patients on the waiting list, but we wished to study how it has specifically affected patients with idiopathic pulmonary arterial hypertension (IPAH)—a condition for which the LAS may not adequately capture the severity of the patient's illness," said Hubert Chen, M.D., M.P.H., assistant professor of medicine at UCSF and lead author of the study.

To investigate the question, Dr. Chen and colleagues obtained data for all lung transplant registrants in the U.S. listed between May 4, 2002, and May 3, 2008. They simultaneously examined two outcomes—death versus transplant—for the nearly 8,000 registrants diagnosed with COPD, IPF, CF or IPAH and compared the "Pre-LAS" period (from May 4, 2002 to May 3, 2005) to the "post-LAS" (from May 4, 2005 to May 3, 2008.)

They were not surprised to find that implementation of LAS was associated with an overall increased likelihood of transplantation and decreased risk of death. However, further analysis revealed that the risk of death for each individual disease except IPAH decreased significantly.

Before the implementation of LAS, the likelihood of transplant was highest for COPD patients and lowest for IPAH patients, even after adjusting for confounding variables including age, blood type and type of transplant. After the LAS, IPAH patients remained the least likely to receive a transplant, despite being at greater risk of death while on the waiting list than either COPD patients or those with IPF.

"The fact that the LAS has led to an overall improvement in the time to transplantation is not particularly surprising," noted Dr. Chen. "But we would hope that those changes would have positively affected all lung transplant candidates, whereas we found distinct differences in the impact according to disease, particular for pulmonary arterial hypertension."

A possible explanation of these findings is the fact that key prognostic indicators in IPAH are not considered under the LAS algorithm. "Hemodynamic variables currently included in LAS, such as pulmonary capillary wedge pressure, provide little information for patients with IPAH," wrote Dr. Chen. "In contrast, mean right arterial pressure and cardiac index, which are known to be strong predictors of mortality for patients with IPAH, are not utilized."

"The LAS has had a positive impact on the majority of wait-listed patients in the U.S.," wrote Kevin Chan, M.D., of the University of Michigan, in an accompanying editorial. "Although the overall likelihood of transplantation has increased and wait-list mortality has fallen, Chen and colleagues show that patients with IPAH are relatively disadvantaged by the current system. Equity of donor lung allocation in the era of LAS is not quite there yet."

Source: American Thoracic Society (news : web)

Explore further: New research demonstrates benefits of national and international device registries

add to favorites email to friend print save as pdf

Related Stories

New prognostic indicator for patients with IPF

Feb 20, 2009

There may be a new way to predict mortality in patients with idiopathic pulmonary fibrosis (IPF), a devastating disease that slowly petrifies the lungs. Most patients live only three years after diagnosis on average; however, ...

Rare lung disease cells indicate higher death risk

Jan 16, 2008

Large numbers of certain cells in the lungs of patients diagnosed with idiopathic pulmonary fibrosis may increase their chance of death, University of Cincinnati (UC) researchers have discovered.

Extreme obesity affects chances of kidney transplantation

Jan 10, 2008

For patients on the waiting list for a kidney transplant, severe and morbid obesity are associated with a lower chance of receiving an organ, reports a study in the February Journal of the American Society of Nephrology.

Recommended for you

New approach to particle therapy dosimetry

Dec 19, 2014

Researchers at the National Physical Laboratory (NPL), in collaboration with EMRP partners, are working towards a universal approach to particle beam therapy dosimetry.

Supplement maker admits lying about ingredients

Dec 17, 2014

Federal prosecutors say the owner and president of a dietary supplement company has admitted his role in the sale of diluted and adulterated dietary ingredients and supplements sold by his company.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.