Pulmonologist Christian Merlo knew for years that lung transplant patients did not fare as well as heart, kidney or liver transplant patients. What he didn’t know was how well the people he treated – CF patients with end-stage lung disease – did after lung transplantation. Were there predictive factors, like the patient’s age, that influenced outcomes following transplant? And was there value in knowing such predictive factors?
The questions were important one, Merlo notes, because lung transplants for CF patients, due in part to a change in the organ allocation system by the United Network for Organ Sharing (UNOS) in 2005, increased significantly over the past decade – from 120 patients per year in 1999 to more than 200 patients in 2009. Consequently, wait-list times are dramatically shorter, too. But lung transplantation, while a viable option for patients with severe end-stage CF, is not without complications. And who the best CF candidates are for lung transplant could be better answered with a fresh review.
So Merlo, cardiac surgeon Eric Weiss and other co-investigators at Johns Hopkins dug deep into the UNOS organ transplant registry from 1999 to 2007. Surprisingly, they found that CF lung-transplant patients 35 and older had a higher five-year survival rate – 62 percent – compared with 43 percent for CF lung-transplant patients ages 7 to 20 years (“Lung Transplantation in Older Patients with Cystic Fibrosis: Analysis of UNOS Data,” The Journal of Heart and Lung Transplantation, February 2009). Also, the researchers found that increasing age was strongly associated with decreases in early post-operative infections, the development of bronchiolitis obliterans – inflammation of the small airways in the lungs – and hospitalizations for rejection. Why?
“We can speculate but we don’t know why that is,” says Merlo. “Maybe someone who is older is more responsible, more compliant with their medications. Or maybe there’s a difference in social support. All these questions deserve future investigations.”
Interestingly, Merlo also found that CF lung-transplant patients tend to do better than lung-transplant patients with other lung conditions, including chronic obstructive pulmonary disease, pulmonary fibrosis and pulmonary hypertension. But there are also unique issues for the CF patient considering lung transplant, including the risk of diabetes, osteoporosis and distal obstructive intestinal syndrome (DIOS) – all of which increase with the administration of immune suppressants following organ transplantation. Another issue for CF patients, Merlo notes, is pancreatic insufficiency, or the inability to maintain proper nutrition.
“Patients have to be supplemented with pancreatic enzymes, which is something a CF clinic is used to dealing with,” says Merlo. “But a transplant clinic may not be used to managing issues like this.”
There are many important factors that go into the organ allocation score developed by UNOS, Merlo adds, but, as his research reveals, there are other predictive factors unique to the CF patient undergoing transplant. Noting that he and Johns Hopkins pulmonologist Noah Lechtzin are analyzing lung-transplant outcomes for CF patients with multiple antibiotic resistant Pseudomonas aeruginosa, as well as looking at outcomes at medical centers that perform more lung transplants in CF patients, Merlo concludes, “The thread for us are the factors that may predict post-transplant outcomes, that will help us risk stratify and guide CF patients considering lung transplantation. Also, these studies have given us some insight into how we can improve our treatment and delivery of care, so that patients and their outcomes will get better.”