Longitudinal changes in growth parameters are correlated with changes in pulmonary function in children with cystic fibrosis

Objective. Nutritional status is associated with pulmonary health and survival in children with cystic fibrosis (CF). This study evaluated the weight gain pattern of children with CF in relation to the longitudinal trends of their pulmonary function. Our hypothesis was that children who experience continuous weight gain at a given rate will have better average forced expiratory volume in 1 second (FEV₁) and change in FEV₁ than children who have weight gain patterns that deviate from this rate, even when total weight gain seems adequate. Methods. Prospectively collected data were examined in 319 children, aged 6 to 8, who were routinely followed at the Minnesota Cystic Fibrosis Center. One to 67 measurements of weight (kg), height (cm), and FEV₁ (mL) were taken per child during this 2-year period. The data were analyzed by repeated measure regression analysis and by growth pattern analysis. Results. At baseline, a 1-kg higher initial weight was associated with a 55-mL higher average FEV₁. During the follow-up period, a 1-kg gain in weight was associated with an increase in FEV ₁ by 32 mL. Children who had a steady weight gain tended to experience greater increases in FEV₁ than children who experienced periodic losses in weight. Conclusions. We established that children who weigh more and who gain weight at an appropriate and uninterrupted rate have a better FEV₁ trajectory. Aggressive nutritional support to maintain growth in these children may therefore improve FEV₁ which can be taken as a surrogate for better lung health, and may ultimately lead to better survival.