Assessment of Inhaled Corticosteroid Adherence in Adults with Severe Asthma Receiving Biologic Therapy: A...

Inhaled corticosteroids (ICS) remain the cornerstone of long-term asthma management. However, adherence to inhaled therapy is frequently suboptimal, even among patients with severe asthma. Biologic therapies substantially improve clinical outcomes, which may unintentionally influence adherence to maintenance inhaler therapy.

To evaluate adherence to inhaled controller therapy in adults with severe asthma receiving biologic treatment and to identify clinical factors associated with inhaler non-adherence.

This single-center retrospective observational study included 173 adults with severe asthma receiving anti-IgE or anti-IL-5/IL-5Rα biologic therapy for at least 12 months. Adherence during the 12-month biologic treatment period was assessed using pharmacy dispensing records (PDR) and the 10-item Test of Adherence to Inhalers (TAI). Non-adherence was defined as medication possession ratio (MPR) <80% and/or TAI score ≤45. Baseline Asthma Control Test (ACT) scores and FEV₁ (% predicted) values were recorded prior to biologic initiation. Multivariable logistic regression was performed to identify independent predictors of inhaler non-adherence.

Overall, 49.1% of patients were classified as non-adherent when both methods were considered. Non-adherence rates were 38.2% according to PDR and 29.5% according to TAI (TAI ≤45). Agreement between methods was fair (κ = 0.37, p < 0.001). Higher baseline ACT scores measured prior to biologic initiation were independently associated with inhaler non-adherence (OR 1.26, 95% CI 1.15-1.38, p < 0.001). FEV₁ (% predicted) was not significantly associated with adherence status. Adherence to biologic therapy was substantially higher (90.8%) than adherence to inhaled therapy.

Inhaler non-adherence remains prevalent among patients with severe asthma receiving biologic therapy. Higher baseline ACT scores independently predict this risk. Routine multidimensional adherence assessment and structured patient education remain essential.