Therapy and Management | Treatment | Daily practice | Trial outcome

Trial outcome and correct use of inhalation devices

Numerous randomised controlled clinical trials exist evaluating the efficacy of different types of devices. Most studies, especially in the outpatient setting, selected for patients, who were carefully instructed and trained in the use of their device and who were able to use them correctly. Pooled metaanalyses found out that under these conditions no significant differences were observed between devices in any efficacy outcome in any patient group.

Unfortunately these findings do not reflect a "real-world" situation and fail to address considerations important for choosing a particular device for a specific patient in a specific clinical situation. These include for example the ability to use a device, patient's preference, availability of certain equipment and costs. However some trials, which studied patient preference found out, that most asthmatics favoured the use of a DPI over an MDI.

A large study including more than 3900 asthmatics using a pMDI without spacer clearly demonstrated that asthma control is highly correlated with the correct use of the inhalation device: Significantly higher asthma instability scores were observed in patients defined as misusers. However similar results may be expected with other devices assuming an equally high rate of misusers. But other studies comparing different types of devices concerning their correct use revealed that in general a considerably higher rate of patients using pMDIs made mistakes compared with patients using DPIs.


Dolovich MB, Ahrens RC, Hess RD, Anderson P, Dhand R, Rau JL, Smaldone GC, Guyatt G. Device selection and outcomes of aerosol therapy: evidence-based guidelines. 2005. Chest; 127 (1): 335-371

Giraud V, Roche N. Misuse of corticosteroid metered-dose inhaler is associated with decreased asthma stability. 2002. European Respiratory Journal; 19: 246-251

Correlation of asthma instability score (AIS) and errors in inhalation technique

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