(33) Cystic Fibrosis in the United States by 2040: a population landscape analysis

Background: The network of Cystic Fibrosis (CF) Foundation-accredited care programs partner with people with CF and their families to provide specialized disease management utilizing a multi-disciplinary approach. Currently, there are 128 pediatric, 119 adult, and 40 affiliate CF programs in the US. In the past decade, the introduction of highly effective modulator therapies (HEMT) ivacaftor (IVA) and elexacaftor/tezacaftor/ivacaftor (ETI), in combination with other advances in CF care, has improved survival for persons living with CF, as approximately 57% of people with CF are adults (18 years or older). In 2020, median predicted survival was estimated at 50 years of age for individuals born between 2016 - 2020 compared to 30 years old in the early 1990s. Given the potential for slower lung function decline with HEMT, survival will likely increase further, requiring CF care programs to serve a growing adult population. The objective of this analysis was to forecast the CF population in the United States through 2040, and predict the distribution of lung function and first transplants, to inform planning for the future of CF care.

Methods: We implemented a simulation to predict the size and characteristics of the CF population from 2021 to 2040, simulating FEV₁% predicted, lung transplantation, and survival status. We used data from the Cystic Fibrosis Foundation Patient Registry to characterize the distribution of persons with CF by age, sex, race/ethnicity, HEMT eligibility, and prescription status. We applied those distributions to a simulated 2020 prevalent population and projected CF births to 2040. The microsimulation used estimates of the probability an individual would transition between lung function categories defined by FEV₁% predicted (High: >90%; Moderate: >70-90%; Low: 40-70%; Severe: < 40%), undergo lung transplant or death derived from logistic regression models using longitudinal data for 2010-2020, with transition probabilities dependent on HEMT prescription status.

Results: By 2040, we estimate adults with CF will comprise over 70% of the total CF population. The proportion of adults classified as >90% FEV₁% predicted will range from 35%-40% over this period, with nearly 80% of children with FEV₁% predicted at this level or higher. The age of first transplant will increase over the next 20 years, with over half of first transplants occurring among individuals over 35 years of age compared to 37% reported in 2020.

Conclusions: While CF has been historically characterized as a pediatric disease, we predict continued growth of the adult CF population over the next 20 years due to increased survival as well as a decline in CF births. Due to slower decline in lung function, age at time of lung transplant will increase resulting in an older post-lung transplant population. This growing and aging adult CF population will likely be more medically complex due to extra-pulmonary and age-related comorbidities, therefore, coordination of care between CF care teams, sub-specialists, and transplant centers will remain critical. The need to grow the workforce knowledgeable in the nuances of multidisciplinary adult CF care is more important than ever.

Acknowledgements: The authors would like to thank the Cystic Fibrosis Foundation for the use of CF Foundation Patient Registry data to conduct this study. Additionally, we would like to thank the patients, care providers, and clinic coordinators at CF centers throughout the United States for their contributions to the CF Foundation Patient Registry.

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