Critical handling errors with dry-powder, metered dose and soft-mist inhaler devices in an observational COPD study

Background: The effect of inhaled therapy is dependent on the patient´s ability to use the inhaler devices correctly. The aim of this study was to evaluate inhaler technique and critical handling errors of the inhalers used by patients with chronic obstructive pulmonary disease (COPD). Methods: COPD patients (59% female, mean±SD age 69±8 years, FEV1 54±17% predicted) were included in the prospective multicentre TIE-study in Sweden. Patients´ inhaler handling with single-dose dry-powder (sDPI), multi-dose dry-powder (mDPI), soft-mist (SMI) and pressurized metered dose (pMDI) inhalers were examined at the study visit based on a list of predefined critical errors: preparing the inhaler device, positioning the inhaler, preparing/loading the dose and exhalation into the mouthpiece. Results: Out of 689 observed inhalation episodes (190 sDPIs, 435 mDPIs, 52 SMIs and 12 pMDIs) in 372 patients, a total of 234 critical errors were observed. The percentage of patients performing at least one critical error was 48%. The most common error was incorrect positioning of the inhaler, observed in 131 (35%) patients. Other errors were incorrect preparing/loading of the dose in 73 (20%) patients, exhalation into the mouthpiece in 22 (6%) patients and incorrect preparing of the inhaler device (2%). Of the patients with mDPI, 46% demonstrated at least one critical error. The corresponding numbers were 15% for SMI, 13% for sDPI and 8% for pMDI. Conclusions: Almost half of the COPD patients performed at least one critical error. Incorrect positioning of the inhaler device was the most common type of critical error. The highest frequency of critical errors were observed among mDPI users.