Likelihood of lung transplant in IPF linked to access, ZIP code income

Regardless of disease severity and lung transplant eligibility, patients with idiopathic pulmonary fibrosis who have access to a lung transplant center and live in more affluent areas have a higher probability of undergoing lung transplant.

“As clinicians and policymakers strive to ensure that eligible patients with IPF have equal opportunity to undergo a lung transplant, a better understanding of factors associated with lung transplant is needed,” Aparna Swaminathan, MD, assistant professor of medicine and member in the Duke Clinical Research Institute and the Duke University Medical Center in Durham, North Carolina, and colleagues wrote. “Evaluating the impact of social determinants of health is particularly relevant, as recent studies have demonstrated that cystic fibrosis patients with poor socioeconomic status are less likely to be added to lung transplant waiting lists.”

Researchers analyzed data from 955 patients with IPF (mean age, 70 years; 25.4% women) enrolled in the IPF-PRO Registry from June 2014 to October 2018. The multicenter U.S. registry includes patients with IPF diagnosed or confirmed in the past 6 months. Researchers assessed differential associations between prespecified covariates related to lung transplant eligibility, clinical characteristics and social determinants of health and lung transplant risk compared with mortality.

At 2 years, the event rate for lung transplant was 7.4% and mortality rate was 16.3%.

Age, median ZIP code income and enrollment at a center with a lung transplant program were identified as the covariates with the strongest differential association with lung transplant probability, according to the researchers.

Patients aged older than 70 years were less likely to need a lung transplant (HR = 0.13; 95% CI, 0.06-0.28), but had a higher likelihood for mortality per 5-year increase (HR = 1.41; 95% CI, 1.22-1.64). Living in an area with a higher median ZIP code income was associated with lung transplant with every $10,000 increase (HR = 1.22; 95% CI, 1.13-1.31). However, higher median ZIP code income was not associated with mortality (HR = 0.99; 95% CI, 0.94-1.04). In addition, enrollment at a center with a lung transplant program was associated with lung transplant (HR = 4.31; 95% CI, 1.76-10.54) but not with mortality (HR = 0.99; 95% CI, 0.69-1.43).

Requirement for oxygen use with activity was also associated with lung transplant and mortality, with a stronger association with lung transplant.

Researchers noted that patients with a higher number of comorbidities had an increased likelihood for mortality but not for lung transplant.

“Given the continued progression of IPF despite current treatment strategies, lung transplant is underutilized in IPF,” the researchers wrote. “Future interventions should focus on mitigating inequalities based on socioeconomic and geographical factors.”