Inhaler technique and patient's preference for dry powder inhaler devices

Abstract

Inhaled therapy has a central place in the management of obstructive lung diseases, but a large number of patients are unable to use their inhalers correctly with a consequent reduction in therapeutic benefit. Correct use of inhalers is, therefore, crucial for efficient therapy, and acceptance of the device can improve patients' compliance. The choice of the most appropriate inhaler for a given patient is often not straightforward. The ease-of-use and performance characteristics of the inhaler will markedly influence patients' acceptance of the device, as well the patients' attitudes to their illness and chronic medication use in general. Choosing the most appropriate inhaler for a specific patient and regular assessment of ability to correctly use their inhaler will promote better adherence to therapy with improved disease outcome. Further, patients' preference for a particular inhaler should be taken into consideration. In patients with obstructive airway diseases, inhaler choice is as critical as the choice of medication itself.

Keywords::

• asthma
• COPD
• dry powder inhalers
• inhaler technique
• preference

Inhaled therapy is the cornerstone of pharmacological treatment of asthma and chronic obstructive pulmonary disease (COPD). Published evidence [1] confirms that when used correctly, there is little difference in clinical efficacy between different inhaler types. However, a high percentage of patients worldwide are unable to use their inhalers properly [2,3] with consequent reduction in therapeutic benefit from their medication. Failure to use inhalers correctly can result in poor asthma control and COPD outcomes [4], increased cost [5] and possibly greater risk to the patient from exposure to less well-tolerated alternative treatments. Inability to use inhalers correctly may have very serious consequences in the event of acute exacerbations [6]. Concern about the real-world use of inhalers was recently expressed by an international panel of healthcare professionals [7,8] given that clinical trials involving inhaled therapy tend to exclude patients with poor technique; performance in the real world may not match that demonstrated in clinical trials [4]. Despite heightened awareness amongst clinicians and the development of several new and improved types of inhaler, there has been no sustained improvement over the past 35 years in patients' ability to use their inhalers [2]. Patients' competence in self-administration of inhaled medications is improved by educational interventions [4]. Repeated training in correct inhaler use improves asthma symptoms [9], quality-of-life [10] lung function [11], and reduces the use of reliever medications [12] as well as emergency hospital admissions [12]. Sometimes incorrect use of inhalers is not simply due to patients' lack of competence, but also to deliberate non-adherence by patients (‘contrivance') who use their inhalers incorrectly [13]. This is difficult to understand and may relate to patients' attitudes to medication, to their medication-taking behaviour and relationships with health professionals, and to characteristics (i.e., shape, dimension, cost) of particular inhaler devices.

Patient satisfaction with and preference for a specific inhaler device have attracted increasing attention in recent years, because of the potential impact that patients experiences with their inhalers might have on adherence to therapy and hence long-term outcome [14]. Inhaler preference is now recognised as a valid patient-reported outcome for inclusion in studies of aerosolised drugs [14]. In addition, preference for a particular inhaler has been advocated as a selection tool for choosing the most appropriate inhaler for each patient [1]. Patients do express their preference for particular inhalers and this is associated with increased ease of teaching inhaler technique, as well as increased likelihood the patient will use correctly [15]. Patients who use their preferred inhaler may obtain a greater degree of satisfaction with therapy, which provides benefit for both patients and caregivers [14]. Further, increased satisfaction with particular devices may lead to increased adherence, better clinical outcomes and reduced healthcare expenditure; future research on this is needed. In addition, with current emphasis on the patient as consumer, pharmaceutical and medical device manufacturers are increasingly interested in obtaining patient feedback on their products. It is increasingly common for pharmaceutical companies to add a preference assessment to multicentre clinical trials of inhaled drugs, using another drug–device combination as a comparator. Demonstration of greater satisfaction with one inhaler compared with another provides a marketing advantage and the feedback may also be used to improve products.

In last two issues of the Journal, van der Palen et al. [16,17] identified possible handling errors, including those which might lead to insufficient or no drug deposition (‘critical errors'), in various dry powder inhalers (DPIs) in patients with asthma and COPD. Patient's preference for these devices was also investigated. The authors found that the frequency of errors, either critical or non-critical, and patients' preference were significantly different among DPIs studied. The multidose DPIs (Genuair® and Diskus®) were both easier to use and preferred by patients than single dose DPIs (Handihaler® and Elpenhaler®). Further, the total number of patients that produced errors during the first use of any of the inhalers was high (about 50%), but decreased significantly (about 13%) with the second use after instruction by the trainer. Of note, the inhaler characteristics that appeared to have the most influence on patients' preference were the presence of multiple dosage and the ease of drug dose preparation [16,17]. These findings should be interpreted with caution as inhalation technique and handling errors were subjectively assessed by the investigator without any objective measure of the patients' breathing pattern. Further, the inhaler-handling results were assessed after only 2 weeks of inhaler use; since inhaler errors may develop over time [4], the relevance of these findings for the real-life, long-term use of the devices is unclear; in addition, patient preference may change after some time of regular usage. Despite these limitations, the results of the studies by van der Palen et al. [16,17] are important. They have confirmed the importance of personal training for efficient inhalation drug delivery and reinforces the notion [1,4,8,14] that patients' ability to handle inhalers correctly and the preference for certain devices are important issues for the choice of an inhalation device. Choice of the most appropriate inhaler for a given patient is important because adherence to therapy is likely to be influenced by patients' attitudes and experience in using the device. If the patient feels their therapy is not working, adherence is likely to be poor; reduced efficacy of treatment could also result from incorrect inhaler technique [7].

Choosing the most appropriate inhaler for patient from a vast and growing array of efficient devices, along with regular assessment of inhalation technique, will improve patient compliance which will in turn lead to improved disease outcome. Patients' preference should always be taken into consideration. The authors believe that choosing a device for drug administration in patients with obstructive airway diseases is as critical as the choice of medication itself, and that in future choice of a new compound will be secondary to the need to choose the appropriate inhaler device.

Declaration of interest

The authors have no competing interests to declare and have received no funding in preparation of the manuscript.

Acknowledgment

The authors thank Dr ML Levy for critical reading of the manuscript.