Trajectory Analyses of Adherence Patterns in a Real-Life Moderate to Severe Asthma Population

Abstract

Global Initiative for Asthma step 5 therapies (GINA-5), other than inhaled corticosteroids and long-acting β-agonists in fixed dose combinations (ICS/LABA FDC), often entail more expensive (eg, monoclonal biologics) or less safe (eg, maintenance oral corticosteroids [OCS]) treatments. It is therefore important to assess poor inhaler adherence as a possible cause of suboptimal response to ICS/LABA FDC before additional GINA-5. To determine rates of, and time to, additional GINA-5 after first-year ICS/LABA FDC use, and their association with inhaler adherence. Patients initiating ICS/LABA FDC between 2013 and 2017 were identified from Australian national dispensing data. Group-based trajectory modeling was used to estimate medication adherence patterns. Multivariable Cox proportional hazards models were used to examine the association between adherence trajectories and GINA-5 addition during 2-year follow-up. In total, 3062 new ICS/LABA FDC users were identified, of whom 120 (3.9%) received additional GINA-5 (OCS: 89; long-acting muscarinic antagonists: 39; biologics: <3). Mean time to commencing additional GINA-5 was 705.2 (standard deviation, 1.7) days. Adherence trajectories were nonpersistent use (20%), seasonal use (8%), poor adherence (58%), and good adherence (13%). Although poor adherence was associated with longer time to additional GINA-5 (adjusted hazard ratio: 0.58; 95% confidence interval: 0.35-0.95), over 80% of additional GINA-5 was commenced in poorly adherent patients. Use of ≥2 OCS/antibiotic courses also predicted additional GINA-5. Almost 1 in 20 people with asthma commenced additional GINA-5 after ICS/LABA initiation, most of whom (>80%) were poorly adherent to inhaled preventers. There is a substantial unmet need for inhaler adherence to be addressed before prescribing additional GINA-5.