Our study demonstrates that rates of respiratory inhaler misuse are high among hospitalized patients with asthma and COPD. This is interesting since patients with COPD have higher rates of potential risk factors including insufficient vision and less-than-adequate health literacy. Although greater than one-in-four participants had insufficient vision, and these participants were twice-as-likely to misuse Diskus® devices, we also found that all participants, regardless of diagnosis, were able to learn and master both MDI and Diskus® technique.
Our findings extend the results of previous studies mainly done in outpatient and emergency room settings, that found high rates of inhaler misuse (from 32%-100% of patients).9–13,29,30
Further, our study is unique in that it examines the use of respiratory inhalers for both rescue (e.g., MDIs) and controller medications (e.g., MDI and Diskus® devices) in hospitalized patients with asthma or COPD, two of the most common lung conditions, accounting for more than 50 million individuals in the United States.31
Our results suggest that providing hospital-based instruction can overcome barriers to self-management, such as insufficient vision.
One unexpected finding was the high prevalence (more than one–in-four participants) of insufficient vision in our study population. The majority of participants with insufficient vision did not have their corrective-lenses with them in the hospital; the remainder either had corrective-lenses that were not adequate or had not previously been prescribed corrective-lenses. Vision in the range of 20/50 to 20/100 is considered “disabling” in occupations that require work with numbers or extensive reading, thereby making sufficient vision essential to one’s ability to perform certain vocations or tasks.32
Similarly, this concept can be applied to an individual’s ability to manage chronic diseases on a daily basis. For instance, insufficient vision may serve as a barrier to self-management of asthma or COPD, including the use of medications (e.g., respiratory inhalers). For example, one study reported that poor vision is related to the inability of patients to open medication containers.33
Our study demonstrates that insufficient vision is a newly identified barrier to appropriate inhaler use. This finding is not surprising since patient education is heavily weighted with written materials that are not only too complex for patients with lower levels of literacy,12
but may also include font-sizes too small to be legible for patients with insufficient vision.34
For example, font-sizes on package-inserts for MDI and Diskus® devices are well below the size 14-font used with the S-TOFHLA, instrument,35,36
presenting a potential challenge for patients with insufficient vision.
However, insufficient vision does not appear to fully explain inhaler misuse. For instance, although COPD patients had higher rates of insufficient vision, they had similar rates of misuse compared to patients with asthma. Further, while insufficient vision was significantly associated with Diskus® misuse and the inability to learn MDI technique, we did not find significant associations between insufficient vision and MDI misuse, nor did we find significant associations between insufficient vision and ability to learn Diskus® technique. One potential reason is the relatively modest sample size for some of the tests of associations. It is also possible that unmeasured patient confounders such as cognitive status or hearing, among others, play a role in inhaler misuse and ability to learn inhaler technique. There could also be device-specific factors that increase risk for misuse that need to be better evaluated in future studies. These potential unmeasured patient-specific factors may also explain why, even though patients with COPD have higher rates of inadequate health literacy and insufficient vision, patients with asthma are just as likely to misuse inhalers. Larger prospective studies should evaluate the role of insufficient vision, along with other important patient factors, in inhaler misuse and ability to learn inhaler technique.
It was encouraging that the TTG intervention was able to overcome potential barriers, such as insufficient vision, for learning inhaler technique. Our findings suggest that comparative studies to evaluate the relative effectiveness of intensive approaches (e.g., TTG), compared to less-intensive approaches to inhaler instruction, are needed.
Unlike earlier studies, we did not detect an association between health literacy and inhaler misuse.9,12
Although rates of mastery after instruction were larger for patients with less-than-adequate health literacy (compared to adequate health literacy), differences between the groups were not statistically significant. Because we could not measure health literacy for all study participants, we were inadequately powered to detect a statistically significant association between lower-levels of health literacy and inhaler mastery.
Our study has some limitations. Because we enrolled a predominately minority population with frequent exacerbations and hospitalizations, it is not clear if our findings would be generalizable to all hospitalized patients with COPD or asthma. We did not include a control group when evaluating the effectiveness of TTG; thus we cannot provide information about the relative effectiveness of intensive versus less-intensive approaches. TTG employed trained research assistants to provide the intervention, as opposed to clinicians; additional studies are needed to determine whether TTG is effective and feasible when delivered by clinicians. Although TTG was successful at teaching patients while hospitalized, we have no long-term follow-up data from this study to determine its effectiveness post-hospital discharge (retention), or the cost-effectiveness of TTG. Finally, this was a modest-sized study conducted at two urban academic healthcare centers. Larger multi-center studies are need to confirm our findings and more fully examine vision, health literacy, inhaler technique, and ability to learn inhaler technique during transitions in care.
In conclusion, most patients hospitalized with asthma or COPD were unable to use inhalers correctly, and poor vision is a surmountable barrier to inhaler misuse. Comparative effectiveness studies are needed to examine different approaches to assessing and improving inhaler technique in this high-risk population during transitions from hospital to home.