Connie Yang, Mark Chilvers, Mark Montgomery, Sarah J Nolan

Dornase alfa is currently used as a mucolytic to treat pulmonary disease (the major cause of morbidity and mortality) in cystic fibrosis. It reduces mucus viscosity in the lungs, promoting improved clearance of secretions. This is an update of a previously published review. To determine whether the use of dornase alfa in cystic fibrosis is associated with improved mortality and morbidity compared to placebo or other medications that improve airway clearance, and to identify any adverse events associated with its use. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearching relevant journals and abstracts from conferences. Date of the most recent search of the Group's Cystic Fibrosis Register: 30 November 2015.Clinicaltrials.gov was also searched to identify unpublished or ongoing trials. Date of most recent search: 28 November 2015. All randomised and quasi-randomised controlled trials comparing dornase alfa to placebo, standard therapy or other medications that improve airway clearance. Authors independently assessed trials against the inclusion criteria; two authors carried out analysis of methodological quality and data extraction. The searches identified 54 trials, of which 19 (including a total of 2565 participants) met our inclusion criteria. Three additional papers examined the healthcare cost from one of the clinical trials. Fifteen trials compared dornase alfa to placebo or no dornase alfa treatment (2447 participants); two compared daily dornase to hypertonic saline (32 participants); one compared daily dornase alfa with hypertonic saline and alternate day dornase alfa (48 participants); one compared dornase alfa to mannitol and the combination of both drugs (38 participants). Trial duration varied from six days to three years.Compared to placebo, forced expiratory volume at one second improved in the intervention groups, with significant differences at one, three, six months and two years. There was also a significant improvement in lung clearance index at one month. There was a decrease in pulmonary exacerbations compared to placebo in trials of longer duration. The quality of the evidence from placebo-controlled trials was moderate to high for outcomes of lung function and pulmonary exacerbations. Limited, low quality evidence was available for changes in quality of life from baseline. One trial that examined the cost of care, including the cost of dornase alfa, found that the cost savings from dornase alfa offset 18% to 38% of the medication costs.The results for trials comparing dornase alfa to other medications that improve airway clearance (hypertonic saline or mannitol) were mixed, with one trial showing a greater improvement in forced expiratory volume at one second for dornase alfa compared to hypertonic saline, and three trials finding no difference between medications. In the only trial to assess the combination of dornase alfa with another medication compared to dornase alone, there was no benefit seen with the combination of dornase alfa and mannitol. Evidence of dornase alfa compared to other medications was limited and the open-label design of the trials may have induced bias, therefore the quality of the evidence was judged to be low.Dornase alfa did not cause significantly more adverse effects, except voice alteration and rash. There is evidence to show that, compared with placebo, therapy with dornase alfa improves lung function in people with cystic fibrosis in trials lasting one month to two years. There was a decrease in pulmonary exacerbations in trials of six months or longer. Voice alteration and rash appear to be the only adverse events reported with increased frequency in randomised controlled trials. There is not enough evidence to firmly conclude if dornase alfa is superior to hyperosmolar agents in improving lung function.