Nutritional status and lung function in children with pancreatic-sufficient cystic fibrosis

Abstract

BackgroundThere is a strong association between nutrition and long-term FEV1 in cystic fibrosis (CF), but studies have been driven by data from subjects with pancreatic insufficiency (PI-CF). We thus evaluated the association between body mass index (BMI) and FEV1 percent-predicted (FEV1pp) in children with pancreatic sufficiency (PS-CF) and contrasted it with the association in PI-CF. MethodsWe utilized data from the CF Foundation Patient Registry. The cohort included children born 1995–2010, diagnosed <2 years of age, and who had annualized data on BMI percentile and FEV1pp at ages 6–16 years. Pancreatic status was defined based on pancreatic enzyme replacement therapy. The association between BMI and FEV1 was evaluated using linear and mixed-effects longitudinal regression. ResultsThere were 424 children with PS-CF and 7,849 with PI-CF. The association between BMI and FEV1 differed significantly by pancreatic status: each 10-pct higher BMI was associated with 2% [95%CI = 1.9–2.1] higher FEV1pp in PI-CF, compared to just 0.9% [0.5–1.3] in PS-CF (PINTERACTION < 0.001). Within the at-risk nutritional category (BMI <25pct), each 10-pct higher BMI was associated with 5% higher FEV1pp in PI-CF, but no significant increase in PS-CF. Moreover, in PS-CF, overweight/obesity (BMI ≥85pct) was associated with decreasing FEV1pp. In addition, FEV1pp decline through age 20 years in youth with PS-CF was modest (-0.6% per year) and independent of BMI (BMI*age PINTERACTION = 0.37). ConclusionsIn children with PS-CF, BMI remains an important determinant of lung function. However, it may be less critical to attain a BMI >50th percentile; and BMI ≥85th percentile may be detrimental.