Objective: It is unclear why some patients with cystic fibrosis (CF) succeed ("responders") in recovering from malnutrition and growth faltering after treatment initiation whereas others fail to do so ("nonresponders"). We conducted a study to test the hypothesis that sustained high energy intake (increased EN) and normal plasma essential fatty acid status are critical determinants of treatment responsiveness within 2 years after diagnosis of CF.
Methods: A total of 71 CF children who had pancreatic insufficiency but not meconium ileus and were enrolled in the Wisconsin CF Neonatal Screening Project were studied. Responders were defined by having achieved adequate weight gain, as indicated by a recovery of weight z score (Wtz) comparable to Wtz at birth (WtzBR) within 2 years of diagnosis. Increased EN and sustained normal plasma linoleic acid level (increased pLA) were defined by achieving energy intake > or =120% of estimated requirement for > or =75% of the time and maintaining plasma LA > or =26% of total fatty acids for > or =75% of the time, respectively.
Results: Thirty-two (68%) screened patients and 13 (54%) patients whose CF was diagnosed conventionally recovered WtzBR within 2 years of diagnosis. Screened patients responded at significantly younger ages (mean/median: 6.3/4.3 months) than patients whose CF was diagnosed conventionally (mean/median: 15.8/11.8 months). Proportionately fewer screened patients (33%) achieved increased EN compared with patients whose CF was diagnosed conventionally (73%). However, more screened patients responded to increased EN and recovered WtzBR (91%) than patients whose CF was diagnosed conventionally (56%), although this difference was of borderline significance. Compared with having neither increased EN nor increased pLA, the likelihood of being a responder was greatest with combined increased EN and increased pLA, followed by increased EN only. The positive associations between increased EN and increased pLA to treatment responsiveness remained significant after adjustment for neonatal screening status, baseline height and weight status, and indices of pulmonary disease severity.
Conclusion: Increased EN and increased pLA are critical in promoting adequate weight gain in children with newly diagnosed CF.