How Hand-held Inhalers Can Handicap Asthma Treatment

Incorrect use of hand-held inhalers can compromise asthma and chronic obstructive pulmonary disease (COPD) treatment, but a new meta-analysis of treatment delivery failure finds instructional methods that have improved their effectiveness.

Study lead author James Mahon (pictured), York Health Economics Consortium, York, UK, said the research was not in itself hoping for a particular outcome in terms of which inhaler might be the best, but rather “to be able to understand the scale of inhaler misuse or failure and what factors were associated with misuse or failure."

"The key message from the research was that actually it is difficult to identify what the actual rates of inhaler misuse/failure are and so therefore the reasons for misuse or failure are also difficult to determine," Mahon said.

Mahon and colleagues accessed nine databases to identify 38 studies which had considered the misuse or failure of inhalers. They targeted the period between 2000 through May, 2015, after introduction in the 1990s of the Turbohaler/Turbuhaler (AstraZeneca) and Diskus/Accuhaler (GlaxoSmithKline) that had required changes in usage technique from previous inhaler devices.

In most studies that reported rates of misuse or treatment failure, the range was from 0 to 30% or more. In studies reporting the highest levels, however the researchers found almost all values are over 50% — indicating that half of those patient groups had not received optimal medication dose.

Studies varied widely in how inhaler usage was monitored and in the definitions of failure and misuse, however. Mahon and colleagues were ultimately unable to determine differential failure rates or whether particular patient characteristics were contributing factors. In addition, they found different operating instructions for the same inhaler across studies and instructional resource sites.

"Given the lack of clear definitions and standardization it is unsurprising that the ranges of failure/misuse rates reported vary widely across the included studies and make it difficult to draw meaningful conclusions on the scale of inhaler misuse," researchers wrote.

Mahon and colleagues offered several recommendations for future research design that would facilitate meaningful comparisons between inhalers, usage techniques and patient groups. Recommendations include:

• Identify the inhaler and period of use

• Describe the instructions and how they are conveyed

• Define what constitutes error or misuse of inhaler

• Grade errors from minor to a major error that prevents medication delivery

A comparison of instructional techniques was included in the studies and reviews examined by Mahon and colleagues. Multimedia training was reported as more effective at improving inhaler administration than written instructions, treatment as usual or no intervention, and as effective as instruction from a healthcare professional. In one study, providing training on 3 separate days reduced failure rates to 0.075%.

"This, and the evidence from other studies, suggests that where poor technique is an issue, this is due to the instruction given to patients at least as much as it might be due to poor inhaler design," researchers wrote.

The review of studies on inhaler misuse and treatment delivery failure was published online in the August issue of Respiratory Medicine.

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