Clinician's Commentary on Morgan et al.1

Airway-clearance treatments (ACTs) are an integral part of the physiotherapy treatment regimen for people with cystic fibrosis, along with inhalation therapy and exercise. Autogenic drainage (AD) is an ACT that can be performed without either assistance or equipment, which makes it an attractive option for airway clearance for many people. In clinical practice, AD is often the treatment of choice for people with CF who have collapsible airways and have not been successful in clearing their mucous with other techniques. Morgan and colleagues point out that many people with CF prefer AD and that it is the third most used technique by Canadians with CF, although to date no systematic review examining the effects of AD has been completed. 1 A thorough review of this technique is warranted, as ACTs have a large treatment burden for people with CF. Studies showing the effectiveness of a treatment can help both caregivers and people with CF believe that their time commitment is worthwhile. Although Jean Chevaillier developed AD in 1967, Morgan and colleagues' extensive search found only four studies, just two of them long-term, that were deemed appropriate for inclusion in their systematic review, and the only outcome measure common to all four studies was forced expiratory volume in 1 second (FEV 1), which was underpowered to detect change. The number of participants using AD in each study was low (n ¼ 10–17). 1 Clearly, studies with more participants and/or using different outcome measures are needed, as this technique— though introduced in Canada only in the early 1990s—has been practised for almost 50 years. Investigators who have difficulty in recruiting enough participants from their own sites for a properly powered airway-clearance study should consider a multi-centre trial design. This design is often used in clinical trials to increase the pool of eligible candidates; further, if the aim is to achieve a heterogeneous sample population, a multi-centre design could help achieve that goal. 2 Standardizing how interventions are taught and how outcome measures are administered and measured is also important for proper interpretation of results, not only within a study but across different studies. Morgan and colleagues were unable to do a meta-analysis in their review because of the low numbers of participants and the different methodolo-gies used in the various studies. 1 The two short-term studies both used sputum yield as an outcome measure, but did not use a standardized collection method. …