Fine particulate matter exposure and long-term lung-function trajectory in adults with cystic fibrosis.

RATIONALE: Exposure to fine particulate matter (PM2.5), a major component of ambient air pollution, is associated with worse short-term respiratory outcomes in cystic fibrosis (CF). The relationship between air pollution exposure over time and lung disease progression in CF is unknown.

OBJECTIVE

To elucidate how PM2.5 affects the rate of age-related decline in forced expiratory volume in one second (FEV1) among adults with CF.

METHODS

Retrospective open cohort study of pwCF ≥ 26 years in the U.S. CF Foundation Patient Registry between 2003-2019. Annual average PM2.5 was estimated at the population-weighted center of each participant's zip code using a spatiotemporal model. We examined the effect of PM2.5 on the age-related change in FEV1 z-score by mixed effects linear regression, adjusting for relevant demographic and clinical covariates, and stratifying by 5-year cohorts of birth year to account for secular improvements in FEV1 and PM2.5 over time.

RESULTS

11,392 adults with CF age ≥ 26 contributed 81,944 person-years of follow-up. Mean ambient PM2.5 levels over the study period were 9.1 µg/m3 (7.5-10.4). The average annual age-related change in FEV1 z-score was -0.057 (95% CI -0.081, -0.033). After covariate adjustment, we did not find evidence of an adverse association between PM2.5 and annual change in FEV1 z-score in the overall cohort [+0.002 per 3 µg/m3 change in PM2.5 (95% CI -0.001, 0.005)] or across birth cohorts.

CONCLUSION

In this large U.S. study, we did not detect an effect of ambient PM2.5 exposure at the zip code level on long-term lung function trajectory in adults with CF. Consideration of other windows of potential vulnerability to exposure, such as during childhood, may help further explain the relationship between air pollution and long-term outcomes in CF.

PRIMARY SOURCES OF FUNDING: Cystic Fibrosis Foundation, CIR Northwest, Seattle Children's Research Institute.