Critical inhaler technique errors have been associated with lower treatment efficacy in chronic obstructive pulmonary disease (COPD). We aimed to assess and follow-up critical inhaler technique errors, and to investigate their association with COPD symptoms and exacerbations.

COPD-diagnosed primary and secondary care outpatients (n = 310) demonstrated inhaler technique with inhaler devices they were currently using. Critical errors in opening, positioning and loading the inhaler device, and exhalation through dry-powder inhalers were assessed and corrected, and the assessment was repeated one year later. COPD Assessment Test, the modified Medical Research Council dyspnoea scale and history of exacerbations were collected at both visits.

The proportion of patients making ≥1 critical inhaler technique error was lower at follow-up in the total population (46% vs 37%, p = 0.01) and among patients with unchanged device models (46% vs 35%, p = 0.02), but not among patients with a new inhaler device model (46% vs 41%, p = 0.56). Not positioning the device correctly was the most common critical error at both visits (30% and 22%). Seventy-four percent of the patients had unchanged COPD treatment from baseline to follow-up. Treatment escalation, de-escalation, and switch was observed in 14%, 11%, and 1% of the patients, respectively. No association was found between critical errors and COPD symptoms or exacerbations.

Assessment and correction of inhaler technique was associated with a decrease in critical inhaler technique errors. This effect was most pronounced in patients using the same device models throughout the follow-up period.