Asthma control in the United States: Relationships between short-acting β-agonist and systemic corticosteroid use.

Background: Asthma control assessment is based on impairment (current symptoms) and risk (exacerbation history).

Objective: To understand the extent of uncontrolled asthma, we assessed relationships between prescription fills for systemic corticosteroids (SCS) and short-acting β-agonists (SABA) as risk and impairment markers, respectively.

Methods: Annual SCS and SABA fills among US patients with asthma were evaluated by a retrospective analysis of the IQVIA Longitudinal Access and Adjudication Data. Patients' disease severity was assigned based on the Global Initiative for Asthma step-therapy level. Exacerbations were evaluated by SCS fills within 12 months of a first asthma prescription fill. Uncontrolled asthma was defined as 2 or more SCS and/or 3 or more SABA fills annually. Individual patient relationships between SCS and SABA fills were assessed using Pearson's correlation coefficients.

Results: A total of 4,506,527 patients were included; 15.1% had 2 or more SCS fills, 29.1% had 3 or more SABA fills, and 37.4% fulfilled either or both criteria. If only SCS use was assessed, 21.4% of cases that were treated as mild to moderate and 27.6% that were treated as severe asthma would have been misclassified as controlled. If only SABA use was evaluated, 7.8% of cases treated as mild to moderate and 11.2% treated as severe asthma would have been misclassified. Overall, 80.9% of uncontrolled asthma occurred in patients treated for mild to moderate disease. Among patients with 2 or more SCS fills, the mean SABA fills were 2.9; the correlation between SCS and SABA fills per patient was significant but weak (r = 0.18; P < .001).

Conclusion: High symptom burden and SCS exposures are not limited to severe asthma but are also characteristic of patients treated for mild to moderate disease. Both impairment and risk assessments are required to understand the full extent of uncontrolled asthma across disease severities.