(54) Updated estimates of CF prevalence and participation in the Cystic Fibrosis Foundation Patient Registry in the United States

Background: The Cystic Fibrosis Foundation Patient Registry (CFFPR) collects data on individuals with cystic fibrosis (CF) in the United States (US), with data available since 1986. Data reported via the CFFPR is utilized in a variety of ways, from monitoring CF care program outcomes to testing hypotheses of clinical importance. A large-scale audit of the CFFPR was conducted in 2012 which estimated between 33,292 and 34,327 persons with CF (PwCF) in the US, of which 81-84% participated in the CFFPR. The objectives of this updated analysis are to estimate: (1) the US CF population, (2) overall registry participation, (3) participation in the CFFPR stratified by age, as of 2020.

Methods: We performed a simulation study to estimate the population of PwCF in the US born between 1968-2020. We simulated incident CF births by state and race/ethnicity using US vital statistics data on live births along with published estimates of CF incidence by race/ethnicity for all state-year combinations prior to the introduction of newborn screening (NBS). In state-year combinations after NBS introduction, we accounted for differential rate of CF diagnosis by race/ethnicity and non-consent to estimate incident CF births. Foreign and US territorial births were not included and there was no account for migration. We then used CFFPR-reported deaths from 1986-2020 to extrapolate cumulative survival for all birth cohorts. The simulation was repeated 500 times, with pre-NBS CF birth incidence, post-NBS percent diagnosed, and cumulative survival proportions varying between lower and upper bounds. We performed sensitivity analyses comparing median estimates from the simulation to CFFPR-reported births and CDC-reported deaths from CF. We report median and 2.5^th and 97.5^th percentiles for registry participation as the proportion of PwCF alive as of 2020 with prior CFFPR enrollment as well as the proportion who provided data in 2019 or 2020, by birth cohort.

Results: We estimate the 2020 prevalent population of PwCF born in the United States between 1968-2020 to be 37,244 (95% Uncertainty Interval (UI): 37,030 to 37,450) individuals. A total of 29,505 (79% of the prevalent PwCF population) contributed data in either 2019 or 2020. Participation in the CFFPR differs by age (Figure 1), ranging from 51.9% (95% UI: 44.6%, 62.6%) for those born in 1968 to >90% of the population born in 2009 or later.

Conclusions: Participation in the CFFPR in 2020 varies by age and is highest among children. The estimated proportion of the population that participates in the CFFPR has wider uncertainty intervals among older birth cohorts reflecting different assumptions underlying true CF incidence and cumulative survival proportions. Narrower uncertainty intervals post-2010 reflect the higher proportion of new diagnoses at birth after universal implementation of NBS, as well as larger patient populations. This data suggests universal newborn screening has resulted in earlier referral to CF care centers with increased participation in CFFPR from a young age. CFFPR data remains critical to inform care trends and prioritize CFF initiatives over time.

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.

References: