The Relationship Between Clinical Trial Participation and Inhaler Technique Errors in Asthma and COPD Patients.

Background: Incorrect inhaler use is associated with poorer health outcomes, reduced quality of life, and higher healthcare utilisation in patients with asthma and COPD. Methods: We performed an observational study of pressurized metered-dose inhaler technique in patients with asthma or COPD. Patients were assessed using a six-point inhaler checklist to identify common critical inhaler technique errors. An inadequate inhaler technique was defined as the presence of one or more critical errors. A multivariate logistic regression model was used to determine the odds of an inadequate inhaler technique. Results: During the 14-month study period, 357 patients were enrolled. At least one critical error was executed by 66.7% of participants, and 24.9% made four or more critical errors. The most common errors were failure to exhale completely prior to pMDI activation and inhalation (49.6%), failure to perform a slow, deep inhalation following device activation (48.7%), and failure to perform a breath-hold at the end of inspiration (47.3%). The risk of a critical error was higher in COPD patients (aOR 2.25, 95% CI 1.13-4.47). Prior training reduced error risk specifically when trained by a doctor (aOR 0.08, 95% CI 0.1-0.57) or a pharmacist (aOR 0.02, 95% CI 0.01-0.26) compared to those with no training. Previous clinical trial participation significantly reduced error risk and rate: <3 trials (aOR 0.35, 95% CI 0.19-0.66) and ≥3 trials (aOR 0.17, 95% CI 0.07-0.42). The rate of critical errors was not significantly associated with age, sex, or prior pMDI experience. Conclusion: This study found a high rate of critical inhaler technique errors in a mixed population of asthma and COPD patients; however, prior training and, in particular, multiple previous clinical trial participation significantly reduced the risk of errors.