(352) Evaluation of Outcomes in Black People with Cystic Fibrosis using the CF Foundation Patient Registry

Background: Cystic fibrosis (CF) was classically considered a disease of the White population, but with the advent of comprehensive genotyping and the ongoing discovery of new disease-associated genes, the minority population with CF is growing. However, these such populations with CF are not well characterized. In particular, there remains a paucity of data about Black people with CF.

Methods: We included people enrolled into the CF Foundation Patient Registry (CFFPR) between 1986 – 2019. People were excluded if their race-ethnicity was not recorded, if they had inconsistent dates in the registry, or if they had a lung transplant prior to enrollment or before 6 years of age. Observations for patients between the ages of 6 and 54 were included. Results were stratified by race-ethnicity, and compared using median regression, Fisher's exact, or the Chi-square test. Any pairwise comparisons adjusted the p-values using Holm's method.

The primary outcome was age at lung transplant or death, and patients were censored at either age 54 or their last follow-up, whichever came first. Kaplan-Meier curves were used to summarize age at lung transplant or death, and comparisons between groups were made using log-rank tests. Cox proportional hazards (CPH) regression was used to test whether the age at transplant or death differed between race-ethnicity after adjusting for co-variates. Co-variates included age at diagnosis, gender, insurance status, mutation severity, pancreatic exocrine status, CF-related diabetes (CFRD) status, liver disease, use of dornase alfa, use of CFTR modulator, presence of Pseudomonas aeruginosa / Burkholderia cepacia / MRSA, and lung function by FEV1 (using GLI reference equation).

Results: Blacks with CF were more likely to carry at least one Class I-III mutation (92.1%) compared to other groups (Whites 87.1%, Hispanics 82.7%, Asians 75%, Multiracial/Other 85.4%, Holm’s adjusted p-value for each comparison < 0.001) . Blacks were more likely to carry a diagnosis of CFRD (35.7%) compared to any other race (p < 0.001). Blacks were less likely to have been receiving modulator therapy (15.7%) prior to potential transplant compared to Whites (37.2%, p < 0.001), Hispanics (25.9%, p < 0.001), or Multiracial/other (33.8%, p < 0.001). In terms of the composite primary endpoint of lung transplant or death, our adjusted analysis (Figure did not find a difference in outcomes between Blacks and their White or Asian counterparts. However, compared to people identifying as Black, Hispanics (adj. HR 1.43, 95% CI: 1.21, 1.70) and Multiracial/Other race people (adj. HR 1.42, 95% CI: 1.07, 1.88) were more likely to receive a lung transplant or die, suggestive of worse outcomes in these groups.

Conclusions: This analysis of pre-Trikafta CFFPR data demonstrates that Black people with CF fared similarly to other racial groups with the exception of the Hispanic and Multiracial/Other groups, who demonstrated worse outcomes.

Acknowledgements: We would like to thank the CFF for providing us with registry data.

References: 1) Buu, M et al. "Assessing Differences in Mortality Rates and Risk Factors Between Hispanic and Non-Hispanic Patients With Cystic Fibrosis in California." CHEST FEBRUARY 2016, pp 380-389.

2) Rho, A. et al. "Hispanic Disparity in Cystic Fibrosis." Am J Respir Crit Care Med Vol 198, Iss 8, pp 1055–1063, Oct 15, 2018

3) Nick, J et al. "Effects of Gender and Age at Diagnosis on Disease Progression in Long-term Survivors of Cystic Fibrosis." Am J Respir Crit Care Med Vol 182. pp 614–626, 2010