Respiratory rate in infants with Cystic Fibrosis and healthy controls throughout the first year of life

Introduction: Lung impairment in Cystic Fibrosis (CF) begins in infancy. Respiratory rate (RR) is a key vital sign that is easy to assess during sleep in infancy and is known to be elevated during acute respiratory disease. Thus, elevated respiratory rate could indicate early lung impairment and potentially serve as diagnostic tool in early disease monitoring. Aim of the study was to compare RR and its change over time between infants with CF and healthy controls. Methods: We included infants with CF from the Swiss Cystic Fibrosis Infant-Lung-Development-Cohort and healthy infants from the Basel-Bern Infant-Lung-Development-Cohort. Throughout the first year of life, parents measured RR weekly during sleep and reported respiratory symptoms. We used multilevel linear regression to compare RR between infants with CF and healthy infants, adjusting for respiratory symptoms and other potential determinants of RR. Results: The analyses included 4509 measurements made in 110 infants of which 30 had CF. RR declined from 44.8 (41.2)/min at 5 weeks of age to 27.5 (24.8)/min at 50 weeks of age in infants with CF (healthy controls, respectively). Infants with CF had consistently higher RR than controls even after adjustment (estimated difference from multilevel linear regression: 3.48/min; 95% CI [1.94,5.03]; p Conclusion: Infants with CF have a higher RR compared to healthy controls. Therefore, the RR might be used as a sensitive and promising marker to monitor early CF disease.