Cognitive function and inhaler technique following recovery from exacerbations of COPD

To the Editor:

Persons with COPD are at elevated risk of cognitive impairment. Cognitive deficits may be more common in those with very low lung function [1], in those requiring supplemental oxygen [2] and during hospitalisations for acute exacerbations [3]. Cognitive impairment is also associated with poor medication adherence and inhaler technique [4]. However, cognitive function is not currently assessed as part of routine management of COPD. The effect of cognitive function on inhaler technique and COPD-related healthcare use such as hospitalisations or emergency department (ED) visits is not well known. To investigate this, we conducted a prospective observational study of cognitive function and inhaler technique among patients with COPD at high risk of increased healthcare utilisation by virtue of having a recent acute severe COPD exacerbation.

We enrolled consecutive individuals who participated in the Minneapolis Veterans Affairs (VA) COPD case management programme, which identifies all patients hospitalised or in the ED for acute exacerbations of COPD and provides nursing-led assistance in outpatient COPD management after discharge. Case management participants were enrolled during their first post-exacerbation clinic visit, which occurs ∼2–6 weeks post-exacerbation. After obtaining informed consent, participants were screened for cognitive impairment using the Montreal Cognitive Assessment (MoCA) by a trained and certified physician (author B.E. Henkle). In addition, participants completed the Hospital Anxiety and Depression Scale (HADS) and the Rapid Estimate of Adult Literacy in Medicine – Short Form, and inhaler technique was assessed using a standardised form that documents the correct steps completed for different inhaler devices (i.e. metered dose inhaler (MDI), Respimat inhaler). Assessment of inhaler technique was conducted by COPD nurses blinded to MoCA and HADS results. Incorrect inhaler technique was defined as completing ≤75% of steps correctly. Chart review was conducted to collect demographic variables, medical comorbidities, active medications and lung function variables (forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁) and FEV₁/FVC ratio). 12 months after enrolment, a chart review was conducted to document use of home systemic corticosteroids and/or antibiotics for COPD exacerbations, ED visits and hospitalisations. The total number of healthcare encounters was calculated by adding the number of independent ED visits and hospitalisations for any cause. A logistic regression model was used to evaluate the association between an abnormal MoCA score (defined using the standard clinical threshold of <26 to identify those at risk for mild cognitive impairment and dementia [5]) and inhaler technique. Poisson regression with an offset for log-days of follow-up was used to evaluate associations between abnormal MoCA and healthcare utilisation and use of home corticosteroids and/or antibiotics. Analyses were completed in R (R Core Team, 2022; version 4.2.0), and all p-values were two-sided. This study was approved by the Minneapolis VA institutional review board.

Between July 2019 and February 2020, we enrolled 47 male study participants (table 1), of whom 29 (62%) had a MoCA score <26 (concerning for mild cognitive impairment or dementia). At enrolment, time since last exacerbation was a median of 39 days (interquartile range 29.5–75.0 days). Characteristics associated with MoCA score <26 were black race, lower educational attainment (≤high school diploma or General Education Development test), prescription of supplemental oxygen and enrolment in home health services. Elevated symptoms of anxiety (HADS-Anxiety >8) were present in 33% (15 out of 47) of participants and elevated depressive symptoms (HADS-Depression >8) were present in 24% (11 out of 47) of participants. 97.8% (44 out of 45; two participants were missing data) were prescribed an MDI. Compared to those with normal-range MoCA scores, those with abnormal MoCA had higher odds of incorrect MDI technique (OR 5.5, 95% CI 1.5–24.2), and this remained statistically significant after adjusting for age, race, education, HADS-Anxiety score, HADS-Depression score and health literacy (OR 18.9, 95% CI 2.7–402.0) (table 1). During 12 months of follow-up (mean 348.2±57.3 days), among 34 participants there were 81 healthcare encounters, including 43 ED visits (of which six were COPD-related), and 38 hospitalisations (of which 11 were COPD-related). Five participants died during follow-up. After adjustment for age, race and education, there was no difference between those with normal and abnormal MoCA scores in rates of home corticosteroid and/or antibiotic use (among 86 events; incidence rate ratio (IRR) 1.38, 95% CI 0.86–2.28), total healthcare use (IRR 0.75, 95% CI 0.47–1.21), hospitalisations (IRR 0.90, 95% CI 0.45–1.85) or ED visits (IRR 0.63, 95% CI 0.33–1.21) through 12 months of follow-up (table 1).

Cognitive impairment is highly prevalent in persons recovering from COPD exacerbations. In our cohort of outpatients with a recent hospitalisation or ED visit for a COPD exacerbation, 62% screened positive for possible mild cognitive impairment or dementia by the MoCA (<26). This is consistent with past research that has found cognitive impairment in up to 57% of COPD patients during an acute exacerbation hospitalisation [3] and anywhere between 13.5% and 73% of stable outpatients, depending upon the measure used [6]. To our knowledge, this is the first report of cognitive assessment in the post-exacerbation recovery period, which represents a particularly vulnerable period for re-hospitalisations, care transitions and medication changes.

MDIs were the most prescribed type of inhaler device in this cohort. Importantly, after controlling for confounding factors, MDI technique was worse in those with impaired cognition. This is consistent with previous work showing that global cognitive abilities are associated with incorrect inhaler use [4]. Notably, incorrect inhaler technique was found in nearly half of our participants. Poor inhaler technique among COPD patients is associated with reduced treatment effectiveness, more acute exacerbations and increased mortality as a result of unintentional nonadherence [7]. Cognitive screening of COPD patients, especially following recent COPD exacerbations, could be a simple intervention to identify those who may benefit from more rigorous inhaler monitoring and support to potentially reduce their risk of exacerbations.

There are several limitations to this study. Due to the coronavirus disease 2019 (COVID-19) pandemic, face-to-face encounters for COPD case management at our institution were discontinued and the study closed at one-third of the target sample size. Due to our smaller than expected sample size, we were unable to fully explore the effect of cognition on non-MDIs such as dry powder or propellant-free devices. It is possible that technique for different styles of inhalers could be influenced differently by cognitive function. Furthermore, the study was underpowered to draw conclusions about our prospective clinical outcomes, as evidenced by the wide 95% confidence intervals for these analyses. In addition to the smaller than planned sample size, COPD patient behaviours during the early phases of the COVID-19 pandemic reduced COPD exacerbations globally [8], and this reduction in the number of outcome events further reduced study power for these clinical outcomes. Additional limitations include that cognition was only evaluated with a single assessment, the MoCA, and this sample of veterans was exclusively male and predominantly Caucasian, which limits generalisability.

Cognitive impairment is highly prevalent in COPD outpatients with recent exacerbations and is associated with poor inhaler technique. Additional studies are needed to assess the value of more widespread cognitive screening in COPD and how cognitive impairment may affect prospective COPD outcomes like hospitalisations and emergency department visits.