Airway clearance techniques for cystic fibrosis: an overview of Cochrane Reviews

We reviewed the evidence from Cochrane Reviews about the effect of airway clearance techniques in people with cystic fibrosis.

Background

Cystic fibrosis is a life-limiting genetic condition that affects the respiratory and digestive systems. People with cystic fibrosis produce thick mucus that builds up in the lungs leading to infections and inflammation and eventually to a deterioration in lung function. People with cystic fibrosis perform airway clearance techniques at least daily to help keep their lungs clear of mucus. There are various airway clearance techniques, which differ in terms of the need for assistance or equipment, and cost. The airway clearance techniques included in this overview are conventional chest physiotherapy, various breathing techniques (active cycle of breathing technique, autogenic drainage), devices that create a positive pressure (positive expiratory pressure therapy (PEP) or high-pressure PEP therapy) or a vibration (oscillating devices) to move mucus, and exercise.

The condition is progressive and as lung function worsens, airway clearance techniques may not be sufficient. It may be useful to consider other therapies, such as hypertonic saline or dornase alfa, in addition to airway clearance techniques. These additional therapies are not covered in this overview.

Search date

The evidence is current to: 29 November 2018.

Study characteristics

This overview included six Cochrane Reviews. One review compared any type of chest physiotherapy (conventional chest physiotherapy, PEP therapy, high-pressure PEP therapy, active cycle of breathing technique, autogenic drainage, exercise, vibrating (oscillating) devices) with no chest physiotherapy or coughing alone. The remaining five reviews included head-to-head comparisons of different airway clearance techniques, thus these five reviews often overlapped with each other.

Key results

In this overview, we found moderate evidence that PEP therapy and vibrating (oscillating) devices have a similar effect on lung function (forced expiratory volume in one second (FEV1) after six months of treatment. We are unable to draw definitive conclusions for all other comparisons in terms of FEV1 because the quality of evidence is currently lacking. Likewise, we are unable to draw any definitive conclusions for other outcome measures such as individual preference and quality of life. Harms, such as acid reflux, collapsed lungs, coughing up blood, or decreased oxygen, were rarely mentioned in the original trials. There is a lack of evidence to determine if any particular airway clearance therapy is riskier than the other therapies.

Quality of the evidence

All of the reviews were considered to be well-conducted. However, the individual trials included in the reviews often did not report enough detailed information to allow us to properly determine trial quality. Many trials did not report enough information on outcome measures; it is unclear how this missing information would influence the results. We graded the evidence for lung function when PEP was compared to vibrating (oscillating) devices as moderate, but the evidence comparing different airway clearance techniques for other outcomes, such as individual preference and quality of life was of low or very low quality. More long-term, high-quality trials (where participants are put into groups at random) which compare different airway clearance techniques among people with CF are needed.

Authors' conclusions: 

There is little evidence to support the use of one airway clearance technique over another. People with cystic fibrosis should choose the airway clearance technique that best meets their needs, after considering comfort, convenience, flexibility, practicality, cost, or some other factor. More long-term, high-quality randomised controlled trials comparing airway clearance techniques among people with cystic fibrosis are needed.

Read the full abstract...
Background: 

Cystic fibrosis is a life-limiting genetic condition in which thick mucus builds up in the lungs, leading to infections, inflammation, and eventually, deterioration in lung function. To clear their lungs of mucus, people with cystic fibrosis perform airway clearance techniques daily. There are various airway clearance techniques, which differ in terms of the need for assistance or equipment, and cost.

Objectives: 

To summarise the evidence from Cochrane Reviews on the effectiveness and safety of various airway clearance techniques in people with cystic fibrosis.

Methods: 

For this overview, we included Cochrane Reviews of randomised or quasi-randomised controlled trials (including cross-over trials) that evaluated an airway clearance technique (conventional chest physiotherapy, positive expiratory pressure (PEP) therapy, high-pressure PEP therapy, active cycle of breathing techniques, autogenic drainage, airway oscillating devices, external high frequency chest compression devices and exercise) in people with cystic fibrosis.

We searched the Cochrane Database of Systematic Reviews on 29 November 2018.

Two review authors independently evaluated reviews for eligibility. One review author extracted data from included reviews and a second author checked the data for accuracy. Two review authors independently graded the quality of reviews using the ROBIS tool. We used the GRADE approach for assessing the overall strength of the evidence for each primary outcome (forced expiratory volume in one second (FEV1), individual preference and quality of life).

Main results: 

We included six Cochrane Reviews, one of which compared any type of chest physiotherapy with no chest physiotherapy or coughing alone and the remaining five reviews included head-to-head comparisons of different airway clearance techniques. All the reviews were considered to have a low risk of bias. However, the individual trials included in the reviews often did not report sufficient information to adequately assess risk of bias. Many trials did not sufficiently report on outcome measures and had a high risk of reporting bias.

We are unable to draw definitive conclusions for comparisons of airway clearance techniques in terms of FEV1, except for reporting no difference between PEP therapy and oscillating devices after six months of treatment, mean difference -1.43% predicted (95% confidence interval -5.72 to 2.87); the quality of the body of evidence was graded as moderate. The quality of the body of evidence comparing different airway clearance techniques for other outcomes was either low or very low.

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