No positive effect of rhdnase on the pulmonary colonization in children with cystic fibrosis

Background. Long-term clinical trials have shown that daily treatment with recombinant human deoxyribonuclease (rhDNAse) in patients with mild to moderate cystic fibrosis (CF) improves lung function and decreases the number of respiratory exacerbations. The aim of this study was to analyze the effect of rhDNAse on the bacterial colonization of the airways in children with CF. Methods. This was a retrospective cohort study. From the database of the CF Center Utrecht, we selected two groups, an rhDNAse group (daily 2.5 mg rhDNAse) and a control group (no rhDNAse). Primary outcome parameter was the difference in change in bacterial colonization between the treatment and control group during 1.5-year. Secondary outcome parameters were changes in lung function (FEV1) and pulmonary exacerbations. Results. Children treated with rhDNAse showed no significant changes in bacterial colonization during the treatment period, apart from an increase of P. aeruginosa positive cultures, both compared to baseline (53.1% versus 25%, p<0.05) and control group (no change during study period, 37% versus 37%). The change in FEV1 after one year of treatment was +4.0% in the treatment group versus -0.3% in the control group (p=0.22). There were no significant changes in number of pulmonary exacerbations. Conclusions. This study showed no significant beneficial decrease in bacterial airway colonization during 1.5-year of treatment with rhDNAse. The positive effects of rhDNAse on the lung function can therefore not be explained by a change in airway colonization.