Hoppe JE, et al. - In a pilot study of infants and pre-school aged children with cystic fibrosis (CF), the frequency and clinical impact of pulmonary exacerbations (PEx) were characterized. A higher risk for PEx was reported in children with worse chest radiograph scores as these patients had more frequent PEx over the subsequent 2 years. Data suggested no association of frequent PEx in infants and young children with CF with lower forced expiratory volume in 1 s and forced vital capacity at 7 years, although spirometry in this age group may not be a sensitive marker of mild lung disease and disease progression.