Expectations Versus Reality in Inhalation Technique—A Case–Control Study of Inhalation Technique in Patients with Asthma or COPD

<b>Background/Objectives</b>: Correct inhalation technique (IT) is crucial in the management of airway obstructive diseases. However, inhaler misuse among patients is frequent. The aim of the study was to assess IT and analyze factors influencing inhalation errors in adults with asthma and COPD. <b>Methods</b>: This single-center case-control study involved 180 adults with asthma or COPD. IT was evaluated using a checklist of common errors, a four-grade dedicated scale, and peak inspiratory flow. Patients with correct and incorrect IT were compared across multiple factors, including demographics, disease duration and severity, motivation for treatment, spirometry results, cognitive function, visual or hearing disorders and prior training in inhaler use. <b>Results</b>: A total of 115 patients with asthma and 65 patients with COPD were analyzed. Among them, only 59 patients (32.8%) were treated with 1 inhaler. Sixty-eight patients (37.8%) used all their inhalers properly. Correct IT was observed more frequently among DPI compared to MDI users (<i>p</i> < 0.001). Only 76 patients (42.2%) reported previous training in IT. No differences were found between correct and incorrect inhaler users (MDI or DPI) regarding age, gender, education, treatment motivation, visual or hearing impairments or cognitive disorders. Among MDI users, those with correct IT more often read the drug leaflet (<i>p</i> = 0.015). Among DPI users, proper technique was associated with better self-assessment (<i>p</i> = 0.046) and a higher rate of prior inhalation training (<i>p</i> = 0.001). <b>Conclusions</b>: Most adults with asthma or COPD do not use their inhalers properly, particularly patients using MDI. Insufficient education in the field of proper IT is still a burning issue.