Longitudinal bacterial prevalence in cystic fibrosis airways: Fact and artifact.

Background: Opportunistic bacterial infection is a hallmark of cystic fibrosis (CF) lung disease and early mortality. Poorly characterized prevalence changes have accompanied two decades of health improvements, with CFTR modulators likely to further affect infection epidemiology.

Methods: Bacterial prevalence change trends across birth cohorts were assessed with linear regression using 2001-2019 US CF Foundation Patient Registry data. Informative missingness was assessed, as was age-to-age infection status.

Results: Bacterial prevalence constantly changed from 2001 to 2019, with changes differing across birth cohorts. Informative censoring affected prevalence change for some organisms. Age-to-age infection status changes were greater than net changes in bacterial prevalence and varied by age.

Conclusions: CF infection epidemiology changed over two decades and will continue to do so. Understanding how modulators affect infection epidemiology will require creative designs for longitudinal prevalence change studies emphasizing prevalence changes independent of effects on lung biology.