Growth and long-term lung function in cystic fibrosis: a longitudinal study of patients diagnosed by neonatal screening

Abstract

Objective: So far there is no long-term analysis relating the achievement of growth milestones (such as prepubertal and pubertal take-off and peak velocity) to the course of respiratory function from childhood to adulthood in cystic fibrosis. This study was designed to evaluate linear growth and severity of lung disease, find a correlation between growth and disease severity throughout childhood.

Patients: One hundred sixty-three patients from one center were selected according to: diagnosis by neonatal screening, complete follow-up available (four height measurements/year) until the age of 20, respiratory tests available from the age of 5-6 years until adulthood, lung transplantation, or death. Disease was classified as mild or severe according to FEV(1) (group 1 and group 2). A third group of patients (group 3) consisted of those who died or underwent lung transplantation before the age of 18.

Methods: Individual growth profiles were fitted with a seven-constant nonlinear growth function. A multivariate linear model was fitted, with gender and severity of disease as covariates, and age, height, and height velocity at growth milestones as dependent variables. Data were compared with those of the normal Italian population.

Results: Lung disease severity correlates with delayed prepubertal and pubertal growth milestones. Peak height velocities were significantly reduced in relation to the severity of the disease.

Conclusions: Patients with severe forms of cystic fibrosis exhibit reduced growth velocity values at an early age, before a clear decline in pulmonary function.