Asthma control in patients receiving inhaled corticosteroid and long-acting beta₂-agonist fixed combinations. A real-life study comparing dry powder inhalers and a pressurized metered dose inhaler extrafine formulation

While asthma represents a global public health issue due to high prevalence rates in the general population (ranging from 1% to 18% of the population in different Countries), several studies now indicate that the impact on public health is even more severe due to the difficulty in achieving full disease control with available therapies [1, 2]. Indeed, achieving and maintaining asthma control is the major goal of asthma care. Based on the Global Initiative for Asthma (GINA) 2009 guidelines, asthma control can be assessed by taking into consideration different characteristics including daytime symptoms, nocturnal awakenings, need of rescue medication, limitation of physical activity, and lung function [2]. Randomized clinical trials (RCTs) have shown that current therapeutic asthma treatments are efficient in granting good asthma control [3]. However, efficacy results reported in RCTs are often inconsistent with data observed in real-life settings where asthma control still remains an unmet need for the great majority of patients [1, 4]. Despite the variety of treatment options available and the periodical update of GINA guidelines since 1995, the evidence indicates suboptimal asthma control, even if improvements are evident when comparing more recent data [1] with previous ones [5], in a great number of patients.

However, RCTs are performed under highly controlled settings and in selected populations of patients. Under these controlled conditions, good inhalation technique is usually checked and granted and the importance of compliance is emphasized. Such a level of adherence is not to be expected in real-life settings. In an effort to find a strategy leading to improved asthma care, the International Primary Care Respiratory Group (IPCRG) examined the main factors contributing to poor control of the disease [6]. Among the several identified reasons, wrong diagnosis, smoking, co-morbidities, individual variation in response to treatment, poor adherence, and poor inhalation technique have been described.

Inhalers for fixed combinations of ICS and LABA include pMDIs and DPIs. It is known that choice of the correct inhaler device is crucial since sub-optimal inhalation techniques can result in reduced drug delivery and efficacy and it should be adjusted to different patients [7, 8]. A meta-analysis of RCTs comparing the same drug delivered by different devices concluded that efficacy outcomes do not differ significantly and that pMDIs and DPIs are equally efficacious in clinical settings [9, 10], although studies have shown that there are fewer inhalation errors with some DPIs [11‐13].

A new fixed combination of BDP/F has been recently developed. The innovative formulation of BDP/F pMDI is characterized by extrafine particle size [14] which results in improved lung deposition and allows for uniform treatment of inflammation and bronchoconstriction throughout the entire bronchial tree [15]. This can translate into beneficial asthma outcomes as demonstrated by a significant increase in asthma control vs. a combination of the same drugs (BDP plus F) given as larger (not extrafine) particles [16]. It has been reported that the extrafine formulation of BDP/F allows for a longer duration of the aerosol plume and a reduced need for hand-to-lung coordination, thus facilitating patient inhaler technique [17]. Furthermore, it has been suggested that pMDI inhalation technique for formulations that produce extrafine particles is less critical than with other MDIs [8], because lung deposition is less affected by inhalation flow [18] and coordination [19]. Moreover, the fast onset of bronchodilation may improve patient adherence [20] and contribute to efficacy.

The aim of this observational study was to evaluate the level of asthma control in a group of patients with moderate or severe persistent asthma (at the time of diagnosis) and to compare, in a real-life setting, efficacy outcomes achieved with extrafine BDP/F delivered via pMDI vs. ICS-LABA combinations (FP/S and BUD/F) delivered via DPIs.

This is the first real-life study comparing the clinical effects of BDP/F extrafine to other combinations. Previously published RCTs found that there were no differences between BDP/F extrafine pMDI and BUD/F or FP/S in terms of lung function, use of rescue medications, exacerbations and safety [22, 23]. However, these studies do not reflect routine use, during which compliance or each patient's ability to use the device may influence the result. In addition to the improved lung deposition and distribution, there is less reliance on using an optimal inhalation technique for pMDIs formulated with extrafine particles [8]. Although these were not assessed in this study, the result would include these elements. Previous studies have shown that, when inhalers emitting large particles are used, the magnitude of inhalation technique errors for a pMDI and DPI are similar [12].

The results show that asthma control was significantly better in patients receiving BDP/F extrafine pMDI formulation compared to the DPI group. Daytime symptoms and use of rescue medications were significantly lower in the BDP/F extrafine pMDI group, further supporting a greater control of asthma in a real-life setting. Asthma is an inflammatory disorder affecting both central and peripheral airways [24, 25], which justifies the clinical need for anti-asthmatic medication which is also able to reach peripheral airways. The inverse correlation on particle size and pulmonary deposition is well known [26]. Of the fixed combinations of ICS currently available on the market, BDP/F extrafine pMDI drug particles are approximately half the size in diameter compared to FP/S and BUD/F DPIs [17]. BDP/F extrafine pMDI is the only fixed combination which has been demonstrated to reach not only large, but also small airways when administered in asthmatic patients [15]. Accordingly, the improved drug delivery, which enables a more uniform treatment of inflammation and bronchoconstriction throughout the entire bronchial tree, contributes to the higher level of asthma control achieved with BDP/F extrafine combination in this study. In other words, extrafine BDP/F can reach and treat distal areas of the lung left untargeted by larger particle sized medications, and this translates into a greater clinical benefit for patients. A significantly superior asthma control with the BDP/F extrafine combination vs. the combination of the same drugs (BDP plus F) given as larger particles, non extrafine agents, has been found in a large 6-month RCT carried-out in asthmatic patients [16]. However, in this study, the definition of asthma control was established according to Zetterström [27] and was therefore different from the GINA guidelines, which is a limitation of our analysis. No differences in lung function parameters were observed among treatments. This finding is not surprising considering that the spirometric tests performed in this study do not provide comprehensive evaluation of the entire bronchial tree as they are unable to properly reflect small airway abnormalities.

In our real-life study, current or former smokers were not excluded since they represent a large proportion of asthmatic patients. Generally, the level of asthma control in smokers was similar to that in non smokers; however, the proportion of uncontrolled patients was significantly increased in these patients as compared to never smokers. Smoking asthmatics are mostly excluded from clinical trials, therefore only sparse data are available on asthma control in current or former smoker asthmatic patients.

Notably, these results were obtained with a lower mean daily ICS dose indicating that BDP/F extrafine delivers a greater efficacy per μg of steroid when compared to BUD/F and FP/S. This is of interest considering that reduced compliance in asthmatic patients is often due to steroid phobia, an issue that can be decreased by offering a medication with a low corticosteroid dose [28].

In the studied population, 45.9% of patients had controlled asthma, 38.7% were partially controlled, and 15.3% were uncontrolled. These findings are in agreement with recent observational trials focusing on asthma control. A study performed across 10 different European countries showed that asthma is suitably controlled in 45% of non-inhaled corticosteroid users and only in 15% of patients using ICS [1]. Similarly, a web-based survey to assess the prevalence of uncontrolled asthma in the United States reported that symptoms were successfully controlled in 45% of patients [29].

This real-life observational study shows that GINA-based asthma control is achieved in a good proportion of asthmatic patients treated with fixed combinations of ICS and LABA. Patients treated with BDP/F extrafine pMDI achieved a greater level of asthma control as compared to patients treated with FP/S or BUD/F larger particle combinations, suggesting that differences in inhaler devices and formulations can have an impact on important clinical outcomes and should be therefore taken into consideration when managing patients with asthma.

In asthmatic patients with comparable disease severity, the use of extrafine BDP/F combination formulated in a pMDI demonstrated better asthma control than using DPI fixed dose combinations formulated with larger particles. This could be due to the improved lung deposition and distribution of the dose or less reliance on the optimal inhalation technique or both.

Henry Chrystyn has no shares in any pharmaceutical companies. He has received sponsorship to carry out studies, together with consultant arrangements with Almirall, AstraZeneca, Boehringer Ingelheim, Chiesi, GlaxoSmithKline, Innovata Biomed, Meda, Napp Pharmaceuticals, Orion, Teva, Truddell and UCB. Research sponsorship has also been received from grant awarding bodies (EPSRC and MRC).

Lilla Tamasi, Veronika Müller, Gabriella Galffy and György Losonczy have no shares in any pharmaceutical companies. All of them have consultant arrangements with AstraZeneca, Boehringer Ingelheim, Chiesi, GlaxoSmithKline, MSD, Pfizer and Nycomed.

Andrea Bizzi and Gabriele Nicolini are employees of Chiesi Farmaceutici S.p.A.

The study was conducted by Semmelweis Medical University, Department of Pulmonology, Budapest, Hungary, without financial support from any pharmaceutical company.