A Six-Month Study of Growth and Energy Expenditure in Children with Cystic Fibrosis Taking a Pulmonary Inhalation Medication (rhDNase)

Abstract

Objective: To characterize the effects of recombinant human deoxyribonuclease (rhDNase) on growth velocity, body composition, resting energy expenditure (REE) and food intake in children with cystic fibrosis (CF).

Methods: A prospective, six-month pilot study was conducted in twenty-one subjects with CF (twelve male, nine female, ages 11.5±3.1 years) measured at baseline, two and six months post-baseline. Repeated measures ANOVA was used to examine the change in variables across time.

Results: The majority (75%) of subjects had minimal lung disease at baseline (FEV₁: 80%–119% predicted). As expected for growing children, weight and height gains (1.6 kg and 2.5 cm) were observed between baseline and six months (p=0.0001). No change was observed in weight z-scores from six months prior to initiation of rhDNase therapy to six months post, though a significant decline (p=0.049) in Ht z-score was observed over this twelve-month period. Triceps skinfolds and mid-arm muscle circumference increased from baseline to six months (p<0.01); respective z-scores remained stable. Energy intake remained constant during the period it was studied from baseline to two months of therapy: 120%±27% RDA. REE, though slightly elevated compared to healthy children (baseline 106%±8% predicted), remained stable throughout the study and at a level which may be expected for children with minimal lung disease. A trend (p=0.057) towards a decrease in the number of subjects requiring hospitalization for pulmonary exacerbations during the trial period was observed.

Conclusions: In summary, these pilot data from younger children with milder CF-related lung disease do not confirm anecdotal reports of improved rate of weight gain, caloric intake or decreases in the elevated REE. Future research might focus on documentation of the possible nutritional effects of rhDNase in clinical trials of children with more severe lung disease.

• cystic fibrosis
• dietary intake
• growth
• Pulmozyme®
• pulmonary function
• rhDNase
• resting energy expenditure

• CF=cystic fibrosis
• FEV₁=forced expiratory volume in 1 second
• FEF_25%–75%=forced expiratory flow at 25%–75% of vital capacity
• FFM=fat-free mass
• FVC=forced vital capacity
• GCRC=General Clinical Research Center
• rhDNase=recombinant human deosyribonuclease commercially known as Pulmozyme®
• RDA=Recommended Dietary Allowance
• REE=resting energy expenditure
• WHO=World Health Organization

This project was supported in part by Genentech Inc., the Nutrition Center and the General Clinical Research Center (NIH-RR-00240) at the Children’s Hospital of Philadelphia. We would like to thank the CF Center staff for their assistance with the project as a whole. Above all we would like to thank the children and adolescents who participated in the study as well as their families for their continued dedication to the research.

Notes

This project was presented in part at the International Symposium on Body Composition, Sweden, September, 1996, and the Tenth Annual North American Cystic Fibrosis Conference, Orlando, FL, October, 1996.