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…