Nebulised hypertonic saline for cystic fibrosis

Abstract

Background: The lung disease in cystic fibrosis is characterised by impaired mucociliary clearance, recurrent bronchial infection and airway inflammation. Hypertonic saline has been shown to enhance mucociliary clearance in-vitro and this may act to lessen the destructive inflammatory process in the airways.

Objectives: To determine if nebulised hypertonic saline treatment improved lung function, exercise tolerance, quality of life and decreased the incidence of exacerbations of respiratory infections in patients with cystic fibrosis.

Search strategy: Studies were identified from the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register. Titles and abstracts were reviewed to identify all controlled trials. Review articles and bibliographies identified from this process were surveyed for additional citations & RCTs. Identification of unpublished work was obtained from abstract books from the three major Cystic Fibrosis conferences (International Cystic Fibrosis Conference, The European Cystic Fibrosis Conference and the North American Cystic Fibrosis Conference). Trial authors were contacted for additional information when only abstracts were available to review. Date of the most recent search of the Group's specialised register: November 1999.

Selection criteria: All controlled trials that assessed the effect of hypertonic saline compared to placebo or other mucolytic therapy, for any duration or dose regimen in subjects with cystic fibrosis of any age or severity were reviewed. Studies in languages other than English were included.

Data collection and analysis: All identified trials were independently reviewed by both reviewers & all data collected. Trial quality was scored by the Cochrane assessment of allocation concealment & the Jadad scale of methodological quality.

Main results: Twelve controlled trials of hypertonic saline were identified. Seven trials met the inclusion criteria; these involved 143 subjects with an age range of 6 to 46 years. Of these, six were published studies and one in abstract form. The durations of the trials were limited to immediate effects on mucociliary clearance to a maximum of three weeks. In two studies, involving thirty five subjects, a score for the feeling of cleared chest was made using visual analogue scales. This analysis showed a weighted mean difference of -0.98 (95% confidence Interval -1.6, -0.34), favouring hypertonic saline over isotonic saline. In two trials with 22 subjects hypertonic saline improved mucociliary clearance as measured by isotope clearance from the lungs in 90 minutes demonstrating a weighted mean difference of -11.3 (95% confidence Interval -18.6, -4.0), and as area under the clearance time curve; weighted mean difference of -212 (95%CI -272, -152), also favouring hypertonic saline over isotonic saline. Lung function as measured by improvement in FEV1 was observed in one study of 27 subjects. The percentage increase in FEV1 at two weeks increased by a mean 15.0% with hypertonic saline and 2.8% with isotonic saline (p=0.004). Adverse events were adequately described in only one trial and none were serious.

Reviewer's conclusions: Nebulised hypertonic saline improves mucociliary clearance immediately after administration which may have a longer term beneficial effect in cystic fibrosis. The maximum time data were recorded for was only three weeks. Most of the patients had mild to moderate lung disease and the effect on severe lung disease remains unclear. Further studies of hypertonic saline should be carried out to determine the effect on pulmonary function tests, quality of life, frequency of exacerbations of respiratory disease and efficacy comparisons with nebulised deoxyribonuclease, with larger numbers and for longer duration. At this stage there is insufficient evidence to support the use of hypertonic saline in routine treatment for patients with cystic fibrosis.