Association between elevated peripheral blood eosinophil count and respiratory outcomes in adults with cystic fibrosis.
Si Cong Ye, Sameer Desai, Emma Karlsen, Eugenie Kwong, Pearce G Wilcox, Bradley S Quon
Author Information
Si Cong Ye: Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
Sameer Desai: School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada.
Emma Karlsen: Pacific Lung Research Centre, St. Paul's Hospital, Vancouver, British Columbia, Canada.
Eugenie Kwong: Pacific Lung Research Centre, St. Paul's Hospital, Vancouver, British Columbia, Canada.
Pearce G Wilcox: Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Pacific Lung Research Centre, St. Paul's Hospital, Vancouver, British Columbia, Canada; Centre for Heart Lung Innovation, St. Paul's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.
Bradley S Quon: Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Pacific Lung Research Centre, St. Paul's Hospital, Vancouver, British Columbia, Canada; Centre for Heart Lung Innovation, St. Paul's Hospital and University of British Columbia, Vancouver, British Columbia, Canada. Electronic address: Bradley.Quon@hli.ubc.ca.
BACKGROUND: Elevated blood eosinophil counts are linked to worse outcomes in asthma and COPD, but have yet to be well characterized in CF. We hypothesized that higher stable visit blood eosinophil counts are associated with increased rates of lung function decline and pulmonary exacerbations (PEx). METHODS: We performed a retrospective analysis of adult CF patients (≥19 years) enrolled from 2012 to 2018 in a prospective cohort study focused on blood biomarkers. We included individuals with at least one year of follow-up post-stable visit blood draw and compared clinical characteristics by blood eosinophil count (<300 cells/µL vs. ≥300 cells/µL). We used multivariate mixed-effects linear regression to estimate annual change in ppFEV. Multivariable poisson and linear regression models were used to estimate rate of PEx requiring IV antibiotics and to compare CF Respiratory Symptom Diary-Chronic Respiratory Infection Symptom Scores (CFRSD-CRISS), respectively. RESULTS: Of 109 patients, 17 (15.6%) had eosinophil counts ≥300 cells/µL. After adjustment for age, sex, BMI, and baseline ppFEV, there was no association between high vs. low eosinophil group and rates of lung function decline (difference in slope -0.04%/y; 95% CI -1.5 to +1.4) or rates of PEx requiring IV antibiotics (IRR 1.46; 95% CI 0.75 to 2.65). The high eosinophil group had a higher mean CFRSD-CRISS score at stable visit (adjusted mean difference 9.3; 95% CI 2.9 to 16.0). CONCLUSIONS: The high eosinophil group experienced increased respiratory symptoms, but the rates of lung function decline and PEx were comparable between groups.
