Assessing adherence to inhaled medication in asthma: Impact of once-daily versus twice-daily dosing frequency. The ATAUD study

ABSTRACT

Introduction: This study was aimed at evaluating whether once-daily regimens (od-r) show benefits in adherence when compared to twice-daily (td-r). Methods: Prospective, multicenter, 6-month follow-up study with two visits. The main objective was to compare adherence assessed by the electronic prescription refill rate (EPRR) and by the 10-item Test of Adherence to Inhalers (TAI) in patients with od-r and td-r. Suboptimal adherence was defined as TAI < 50 or EPRR ≤ 80%. The effect of suboptimal adherence on meaningful clinical outcomes and the concordance between EPRR and TAI were also examined. Results: One hundred and ninety-seven patients (47.3 ± 15.9 years, 65% women) were included and 180 completed the study. TAI score was <50 in 29.8% od-r patients and 46.9% in td-r (p = 0.01) and EPRR was ≤80% in 22.6% and 37.5% respectively (p = 0.02). The correlation between the two methods was moderate (rho = 0.548; p < 0.001). There were no significant differences in FEV₁ (%), symptoms or exacerbations between patients with optimal and suboptimal adherence. During follow-up, five patients (6%) with o-dr and 17 patients (17.7%) with t-dr suffered an exacerbation (p = 0.013). At visit two, 13.1% of the patients with o-dr and 31.3% with t-dr had uncontrolled asthma (p = 0.003), although more patients with o-dr were receiving inhaled corticosteroids in the high-dose stratum (25.8% vs. 11.5%; p = 0.001). Conclusion: Mean adherence rates were greater with od-r than with td-r, but we did not observe an effect on clinical outcomes.

KEYWORDS:

• Asthma
• adherence
• electronic monitoring

Authors' contributions

LPLL was responsible for the conception and design of the study. With the exception of MMV, all authors were involved in patients’ recruitment. All authors were involved in drafting the manuscript and revising it critically for important intellectual content. LPLL and MVV carried out the statistical analysis and interpretation of data. All authors have read and approved the final manuscript.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

The project was endorsed by the Sociedade Galega de Patoloxía Respiratoria (SOGAPAR). The project was funded by an unrestricted grant from SOGAPAR.