Objective: Positive effects of growth hormone therapy on growth, nutritional status, and lung function have been observed in patients with cystic fibrosis, but the current evidence is based on unblinded studies that involved a small number of patients. This trial was designed as a multicenter, randomized, placebo-controlled, double-blind study to assess the efficacy and safety of 2 dosages of growth hormone in cystic fibrosis.
Methods: Sixty-three dystrophic patients with cystic fibrosis were randomly assigned for 24 weeks to 1 of 3 treatment arms: growth hormone dosage of 0.11 IU/kg body weight per day, growth hormone dosage of 0.21 IU/kg body weight per day, or placebo. The 24-week double-blind period was followed by an open treatment period of 24 weeks. The primary outcome measure was the change in forced expiratory volume in 1 second in percentage predicted from baseline. Secondary outcome measures were changes in height, weight, and exercise tolerance.
Results: Height, growth velocity, and growth factors (insulin-like growth factor 1 and insulin-like growth factor-binding protein 3) increased significantly in both treatment groups, whereas weight gain did not differ between the growth hormone groups and placebo. A trend toward improvement in absolute forced vital capacity was observed in patients who received the higher growth hormone dosage, whereas forced expiratory volume in 1 second did not change significantly with growth hormone treatment. Maximal oxygen uptake during peak exercise increased significantly in treated patients. There were no significant differences in the frequency or severity of adverse effects or in the incidence of abnormalities in glucose metabolism.
Conclusions: These data suggest that in the group investigated, growth hormone therapy was well tolerated and had positive metabolic effects but did not result in short-term improvement of lung function in patients with cystic fibrosis.