Cognitive impairment according to Montreal Cognitive Assessment independently predicts the ability of chronic obstructive pulmonary disease patients to maintain proper inhaler technique

BACKGROUND: Maintaining correct inhaler technique is crucial in the management of chronic obstructive pulmonary disease (COPD). We aimed to investigate the inhaler technique in patients with COPD, to compare it immediately after and at 1 month after training, and to identify the predictors of incorrect inhaler use at 1 month after training. METHODS: This prospective study was conducted at the COPD clinic of Siriraj Hospital (Bangkok, Thailand). Patients demonstrating improper inhaler use were trained face-to-face by pharmacists. Inhaler technique was re-assessed immediately after and at 1 month after training. The Montreal Cognitive Assessment (MoCA) score, pulmonary function tests, 6-min walk distance (6 MWD), modified Medical Research Council scale score, and COPD Assessment Test (CAT) score were evaluated. RESULTS: Sixty-six patients with COPD who demonstrated at least one critical error during the use of any controller inhaler were enrolled. The mean age was 73.0 ± 9.0 years, and 75.8% patients had moderate/severe COPD. Immediately after training, all patients used dry powder inhalers correctly and 88.1% used pressurized metered-dose inhalers correctly. At 1 month, the number of patients demonstrating the correct technique decreased across all devices. Multivariable analysis revealed that MoCA score ≤ 16 was independently associated with a critical error at 1 month after training (adjusted odds ratio: 12.7, 95% confidence interval: 1.8–88.2, p = 0.010). At 1 month, CAT score (11.4 ± 8.9 vs. 8.4 ± 5.5, p = 0.018) and 6 MWD (351 ± 93 m vs. 372 ± 92 m, p = 0.009) had significantly improved in patients demonstrating the correct technique, and CAT score met the minimal clinically important difference. CONCLUSIONS: Face-to-face training by pharmacists improved patient performance. However, the number of patients following proper technique had decreased at 1 month after training. Cognitive impairment (MoCA score ≤ 16) independently predicted the ability of COPD patients to maintain proper inhaler technique. Assessment of cognitive function combined with technical re-assessment and repeated training should improve COPD management. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12890-023-02448-x.