Prospective evaluation of respiratory exacerbations in children with cystic fibrosis from newborn screening to 5 years of age

Abstract

Background: Newborn screening allows novel treatments for cystic fibrosis (CF) to be trialled in early childhood before irreversible lung injury occurs. As respiratory exacerbations are a potential trial outcome variable, we determined their rate, duration and clinical features in preschool children with CF; and whether they were associated with growth, lung structure and function at age 5 years.

Methods: Respiratory exacerbations were recorded prospectively in Australasian CF Bronchoalveolar Lavage trial subjects from enrolment after newborn screening to age 5 years, when all participants underwent clinical assessment, chest CT scans and spirometry.

Results: 168 children (88 boys) experienced 2080 exacerbations, at an average rate of 3.66 exacerbations per person-year; 80.1% were community managed and 19.9% required hospital admission. There was an average increase in exacerbation rate of 9% (95% CI 4% to 14%; p<0.001) per year of age. Exacerbation rate differed by site (p<0.001) and was 26% lower (95% CI 12% to 38%) in children receiving 12 months of prophylactic antibiotics. The rate of exacerbations in the first 2 years was associated with reduced forced expiratory volume in 1 s z scores. Ever having a hospital-managed exacerbation was associated with bronchiectasis (OR 2.67, 95% CI 1.13 to 6.31) in chest CT scans, and lower weight z scores at 5 years of age (coefficient -0.39, 95% CI -0.74 to -0.05).

Conclusions: Respiratory exacerbations in young children are markers for progressive CF lung disease and are potential trial outcome measures for novel treatments in this age group.

Keywords: Bronchiectasis; Cystic Fibrosis; Respiratory Infection.

Figure 1

Features of respiratory exacerbations according to whether ‘community managed’ or ‘hospital admission’. ¹Respiratory rate z score more than 2 SDs from the mean.

Figure 2

Forced expiratory volume in 1 s (FEV1) z score versus respiratory exacerbation rate during the first 2 years of life. Six patients reported 0 exacerbations in the first 2 years of life. These are shown in the log-scale graph with a value of 0.28, which is the log of half the smallest observed rate.

Figure 3

Rate of respiratory exacerbations in years 4 and 5 versus years 1 and 2 of life. Eleven and two patients reported 0 exacerbations in years 1 and 2, and 4 and 5, respectively. These are shown in the log-scale graph with a value of 0.28 or 0.23, which is the log of half the smallest observed rate in each pair of years.