Assessing and Improving Misuse of Inhalers in COPD Outpatients

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. Most patients rely on inhaled medications to control symptoms and reduce the risk of exacerbations. However, many patients do not use their inhalers correctly. Critical errors-such as incorrect preparation of the device, improper inhalation technique, or an inspiratory flow that is not appropriate for the device-are common and can lead to reduced drug delivery, poorer symptom control, and more frequent exacerbations. Previous studies conducted at the study site have shown that nearly 70% of hospitalized COPD patients used at least one inhaler incorrectly. In addition, peak inspiratory flow (PIF) varies between individuals, and many patients are unable to generate the flow required for certain dry powder inhalers. Despite this, regular assessment of inhaler technique and inspiratory flow is not systematically implemented in outpatient practice.

This randomized controlled trial evaluates whether a structured, physiotherapist-led inhaler-optimization program can reduce incorrect inhaler use among outpatients with COPD. The intervention includes three face-to-face visits over 12 months. During these sessions, physiotherapists trained in inhaler technique assessment use device-specific placebo inhalers and standardized checklists to identify critical errors. They also measure PIF with the In-Check DIAL® device, adjusted to the resistance of each patient's inhaler. The physiotherapist then provides individualized "teach-to-goal" education, with demonstration, correction, and repeated practice until mastery of the inhaler technique is achieved. When persistent errors or suboptimal PIF are identified, the physiotherapist informs the treating physician to consider adapting the type of inhaler.

Participants are randomly assigned (1:1) to the intervention group or the usual-care group. Usual care consists of regular management by the treating physician, which may include inhaler review at the physician's discretion, but without the structured physiotherapist-led sessions. Both groups undergo baseline and 12-month assessments that include inhaler technique evaluation using placebo devices, PIF measurement, respiratory questionnaires, and pulmonary function testing. Participants in both groups also receive telephone follow-up calls at months 2, 5, and 8 to assess symptoms, inhaler use, adherence, and confidence in inhaler use.

The primary endpoint is the proportion of misused inhalers at 12 months. An inhaler is considered misused if the patient demonstrates at least one critical technique error or if their measured PIF is outside the recommended range for their specific device. This composite outcome captures both aspects of inhaler adequacy: correct handling of the device and physiological ability to use it effectively. Because participants may use more than one inhaler device, the primary outcome is assessed at the inhaler level while accounting for clustering within participants. Secondary endpoints include changes in health status measured by validated respiratory questionnaires (CAT and CCQ), treatment adherence using the TAI questionnaire, satisfaction with inhalers, confidence in inhaler use, pulmonary function parameters, and the number of COPD exacerbations and hospitalizations over the 12-month follow-up.

The trial uses a pragmatic design to reflect real-world outpatient care. The inhaler-optimization program is intended to be simple, scalable, and easily integrated into routine COPD management. The educational approach is based on individualized instruction and repeated reinforcement, which patients in prior studies have reported as highly valuable. Outcome assessment at 12 months is performed by assessors who are not involved in delivering the intervention and are instructed to remain blinded to group allocation.

The study is minimal-risk and non-invasive. Potential risks include temporary fatigue or coughing during repeated inspiratory maneuvers and the time required for study visits and follow-up calls. The intervention does not involve investigational products or exposure to radiation. Data are collected according to Swiss data protection regulations using coded identifiers and secure REDCap databases.

By evaluating inhaler technique and inspiratory flow in a structured, standardized manner, this study aims to provide new evidence on how to improve inhaler use in COPD. Results may support more personalized device selection, enhance patient education practices, and reduce COPD exacerbations and associated healthcare burden. The findings may be applicable to a wide range of outpatient settings and could inform future guidelines on inhaler optimization in chronic respiratory diseases.