Current Models Overestimate Survival for Pulmonary Arterial Hypertension (PAH) Patients Awaiting Lung Transplant
Researchers create new equation to gauge patient survival to be presented at International Society for Heart and Lung Transplantation Annual Meeting
MONTREAL, April 27, 2013 – The latest research in pulmonary arterial hypertension (PAH) will be revealed today at the International Society for Heart and Lung Transplantation (ISHLT) 33rd Annual Meeting and Scientific Sessions in Montreal, Canada. The study specifically reviewed past and current methods of predicting survival for PAH patients awaiting lung transplant. Results show that current models are overestimating patient survival. In 409 patients listed for lung transplant after Jan. 1, 2006, only 72 percent were alive at one year. This compares to the current equation known as the pulmonary hypertension connection (PHC), a risk equation developed to predict survival. The PHC equation in this group predicted survival at 92 percent.
Data from the USA Scientific Registry of Transplant Recipients was analyzed on 1,027 PAH patients listed for lung or heart/lung transplantation for the study. To develop the equation, only patients listed after Jan. 1, 2006 were utilized based on the changes in listing procedures.
“Although treatment for pulmonary arterial hypertension has improved, long-term survival, even with therapy, is disappointing. Therefore we set out to determine if existing survival models for PAH are accurate predictors,” said Mardi Gomberg-Maitland, M.D., M.S., Associate Professor of Medicine and Director of Pulmonary Hypertension at the University of Chicago. “In the end a new equation was needed to better predict survival in PAH patients on the waiting list. Greater attention should be drawn to the possibility of separation in listing procedures for these patients.”
PAH is a severe, progressive and life-threatening disorder in which the pressure in the pulmonary arteries is significantly increased due to vasoconstriction, the narrowing of blood vessels. Over time this can lead to heart failure and death. The most common symptoms of PAH include shortness of breath, fatigue, lightheadedness and fainting, all of which increase with exertion. Early diagnosis is essential but as symptoms are non-specific diagnosis is often delayed by two years or longer.
Currently, all PAH patients in the USA are listed for transplant using the same criteria as patients suffering from parenchymal lung disease.
Today’s research calls for the use of separate listing criteria, one model to predict survival in pulmonary vascular disease patients and one for those with parenchymal lung disease.
As a result, researchers developed a new equation to help clinicians best predict survival once the patient is placed on the lung transplant list. The new model is based on advanced statistical modeling techniques and found that a measure of heart function (cardiac output) the amount walked in a six minute walk test, and oxygen supplementation at rest (amount in liters) were the best combined predictors. Further research is needed to identify predictors that account for the survival differences that are not explained by these variables.
The International Society for Heart and Lung Transplantation (ISHLT) is a not-for-profit professional organization with more than 2,700 members from over 45 countries dedicated to improving the care of patients with advanced heart or lung disease through transplantation, mechanical support and innovative therapies via research, education and advocacy. For more information, visit www.ishlt.org .
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