Rationale: Health insurance coverage has been implicated as a socioeconomic factor affecting clinical outcomes in patients with cystic fibrosis (CF), but evidence for this is mixed and varies by age.Objectives: Focusing on adolescents and young adults with CF, we examined how multiyear patterns of health insurance coverage were associated with lung function decline and related outcomes.Methods: We used data from the 2000 to 2015 CF Foundation Patient Registry to classify patients in three cohorts (ages 12-17 yr, adolescents; 18-23 yr, transitioning to adulthood; and 24-29 yr, young adults) according to health insurance coverage, as follows: continuous private, continuous public, intermittent public, and coverage gaps. The primary outcome was the percentage predicted forced expiratory volume in 1 second (FEV1pp), which was modeled using mixed-effects regression. Additional outcomes included outpatient visits, hospital days for pulmonary exacerbation treatment, bacterial colonization, and body mass index. Outcomes were assessed over a 6-year period (e.g., ages 12-17 yr), whereas exposures were assessed over the prior 6 years (e.g., ages 6-11 yr).Results: The three cohorts included 3,365, 2,800, and 1,807 patients, respectively. The highest rate of FEV1pp decline was found in the middle cohort, with the annual decline being steeper among patients with continuous public (-3.1/yr; 95% confidence interval [CI], -3.3 to -2.8) or intermittent public (-2.4/yr; 95% CI, -2.6 to -2.2) coverage compared with patients with continuous private coverage (-2.1/yr; 95% CI, -2.2 to -2.0). These differences were not explained by differences in outpatient care utilization.Conclusions: During the transition to adulthood, use of public insurance was associated with accelerated lung function decline among patients with CF. The role of insurance as a causal factor in this decline or proxy for other socioeconomic characteristics should be explored in further studies.
Keywords: adolescence; cystic fibrosis; health insurance.