Does distance to a cystic fibrosis center impact health outcomes?

Abstract

Introduction: This paper considers the impact of geographic distance from cystic fibrosis centers on lung function in children, young adults, and adults with cystic fibrosis. Methods: Clinical patient-level data on 20 351 patients from 1986 to 2011 were evaluated from the Cystic Fibrosis Foundation National Patient Registry. We measure distance using a patient's zip code centroid to the center where they received care. A heteroscedastic mixed effects model was used to capture the association of distance with longitudinal variation in patients’ lung function. Results: Children, young adults, and adults in lower socioeconomic categories had a %FEV 1 between 3 and 10 percentage-points lower than those living in higher income areas and those privately insured. For patients who changed distance categories, high distance was associated with lower lung function in young adults (P-value <0.001). For older patients we observed the reverse, suggesting that the choice to move farther away is associated with better health (P-value <0.001). For patients who did not change distance categories, only medium distance in children was significant (P-value = 0.01). Known confounding factors including age and CFTR mutation class were statistically significantly associated to health outcomes (P-value <0.001). Conclusions: This study shows distance is not found to be associated with health lung function among patients whose distance category remained unchanged during the analysis. For patients who move, the association of health with distance depends on the age of the patient; adult patients further from their care center are healthier. Overall, we find that socioeconomic and genetic factors appear to impact health outcomes to a greater extent.