Characteristics of Treated Asthmatics Experiencing Exacerbations in a US Database: A Retrospective Cohort Study

Rationale: The National Heart, Lung, and Blood Institute (NHLBI) recommend a stepwise approach to asthma management, with the goals of maintaining asthma control and reducing exacerbations. Although asthma treatments reduce the frequency of exacerbations, they still occur. We aimed to characterize the treated United States of America (US) adult asthma population, including those experiencing exacerbations, in terms of socio-demographics, clinical characteristics, and healthcare resource utilization (HRU).

Patients and methods: A retrospective cohort of asthma patients aged ≥18 years on 01 January 2014 with ≥1 ICD-9 asthma code (493.xx) enrolled in a US healthcare claims database during 2013-2014. Patients who had ≥2 asthma medication dispensings during 2013 (baseline), including ≥1 in the 90-day period before index date, were classified according to NHLBI step. Patients with chronic obstructive pulmonary disease, cystic fibrosis, or lung cancer diagnoses were excluded. Demographics, comorbidities, clinical characteristics, and HRU were described during baseline. Exacerbations and HRU were described during 2014 (follow-up period).

Results: In total, 72,156 patients were included; 10,590 (14.7%) had ≥1 exacerbation during follow-up. Approximately 44% of patients were classified as NHLBI Steps 1-2, 41% as Steps 3-4, and 11% as Steps 5-6. Exacerbation frequency increased with step (Steps 1, 2, and 3: 12-14%; Steps 4, 5, and 6: 16-26%). Compared with the overall population during baseline, patients with an exacerbation had similar demographics, but differences were observed for comorbid allergic rhinitis (46.4% vs 40.1%, respectively), blood eosinophil counts ≥300 cells/μL (45.5% vs 39.6%, respectively), and asthma-related healthcare encounters (62.9% vs 52.4%, respectively). Overall, asthma-related HRU during follow-up increased with NHLBI step.

Conclusion: Exacerbations were observed among patients classified at each NHLBI step and were more frequent with increasing step. Exacerbations and asthma-related HRU highlight the continued unmet need in the treated US asthma population.