Abstract: The searches identified 69 trials, of which 19 (2565 participants) met our inclusion criteria. Fifteen trials compared dornase alfa to placebo or no dornase alfa (2447 participants); two compared daily dornase to hypertonic saline (32 participants); one compared daily dornase alfa to 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. Dornase alfa compared to placebo or no treatment Dornase alfa improved forced expiratory volume at one second at one month (four trials, 248 participants), three months (one trial, 320 participants; moderate-quality evidence), six months (one trial, 647 participants; high-quality evidence) and two years (one trial, 410 participants). Limited low-quality evidence showed no difference between groups for changes in quality of life. There was a decrease in pulmonary exacerbations with dornase alfa in trials of up to two years (moderate-quality evidence). 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. Dornase alfa: daily versus alternate day One cross-over trial (43 children) found no differences between treatment regimens for lung function, quality of life or pulmonary exacerbations (low-quality evidence). Dornase alfa compared to other medications that improve airway clearance Results for these comparisons were mixed. One trial (43 children) showed a greater improvement in forced expiratory volume at one second for dornase alfa compared to hypertonic saline (low-quality evidence), and one trial (23 participants) reported no difference in lung function between dornase alfa and mannitol or dornase alfa and dornase alfa plus mannitol (low-quality evidence). One trial (23 participants) found a difference in quality of life favouring dornase alfa when compared to dornase alfa plus mannitol (low-quality evidence); other comparisons found no difference in this outcome (low-quality evidence). No trials in any comparison reported any difference between groups in the number of pulmonary exacerbations (low-quality evidence). When all comparisons are assessed, dornase alfa did not cause significantly more adverse effects than other treatments, 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 from 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 other hyperosmolar agents in improving lung function.

Plain-language summary: We included 19 trials with 2565 people with cystic fibrosis; 15 trials (2447 people) compared dornase alfa to placebo (a dummy treatment with no active medication) or no dornase alfa treatment; two trials (32 people) compared daily dornase to hypertonic saline; one trial (48 people) compared daily dornase alfa with hypertonic saline and alternate day dornase alfa; and one trial (38 people) compared dornase alfa to mannitol and the combination of both drugs. People from all age groups (infants through to adults) took part in the trials which lasted from six days to three years. Dornase alfa compared to placebo or no treatment We found that dornase alfa improves lung function within one month when compared to a placebo or no treatment and this improvement was also seen in longer trials lasting from six months to two years (eight trials; 1708 participants). There were also fewer exacerbations (flare up of lung inflammation) in these longer trials. One trial found that the cost savings from dornase alfa offset 18% to 38% of the medication costs. Dornase alfa - daily versus alternate day One trial (43 children) found no differences between treatment schedules for lung function, quality of life or pulmonary exacerbations. Dornase alfa compared to other medications that improve airway clearance The results from trials comparing dornase alfa to hypertonic saline or mannitol were mixed. One trial (43 children) showed a greater improvement in lung function with dornase alfa compared to hypertonic saline and one trial (23 participants) reported no difference in lung function between dornase alfa and mannitol or dornase alfa and dornase alfa plus mannitol. In one trial (23 participants) quality of life scores were better with dornase alfa alone than with dornase alfa plus mannitol; other drug comparisons found no difference between treatments for quality of life. No trials in any comparison of treatments reported any difference between groups in the number of pulmonary exacerbations. Overall, no serious side effects were reported, with only rash and a change in voice seen more frequently in those people taking dornase alfa. However, it is not definitively clear from the current evidence if dornase alfa is better than other medications such as hypertonic saline or mannitol. The quality of evidence from the trials comparing dornase alfa to placebo or no treatment was moderate to high for lung function results, but only one trial reported any changes in quality of life so the evidence for this outcome is limited. Also, there were few trials comparing different treatment schedules of dornase alfa (e.g. once a day versus twice a day) or comparing dornase alfa to other medications which help with clearing secretions, so current evidence from these trials is limited and of low quality.