Misuse of pressurized metered dose inhalers by asthmatic patients treated in French private practice

Although metered dose inhalers (MDIs) are widely used to treat asthma, clinical studies suggest that misuse is frequent. We studied the frequency of, and factors related to, misuse of MDIs in asthmatic patients of French private practice. 264 chest specialists or general practitioners completed questionnaires including characteristics of patients and asthma, technique in using inhalers and previous instruction, for three consecutive asthmatics aged > 6 years and currently using MDIs: 668 adults (mean age 47.8 years +/- 18.5, 51.8% males) and 100 children (mean age 11.5 years +/- 2.1, 72.0% males) were included. Adequate technique (deep inspiration synchronized with inhaler activation, followed by holding breath for 5 seconds) was used by 33.2% of adults and 26.0% of children; optimal technique (same, plus shaking the inhaler before use and activating it only once) was used by 22.1% of adults and 20.0% of children. The main factor related to misuse of MDIs was absence of previous instruction. However only 26.5% of instructed adults and 22.1% of instructed children used the optimal technique. Misuse of MDIs is a public health problem and instruction is unlikely to solve it. The use of different types of devices, like dry powder breath-actuated inhalers should be encouraged.