Introduction and objective Exacerbations occur in all asthma patients but disproportionately impact those with more severe disease. This study aimed to describe the frequency of exacerbations by asthma severity and the risk for future exacerbation.

Methods In a retrospective cohort of asthma patients in the CPRD (2009–2011), we defined asthma severity based on asthma medication use and exacerbation history; index date was asthma medical code date. Asthma severity was determined by asthma medication use and exacerbation history during the 12 months preceding the index date. Exacerbations were ascertained during the 12-month follow-up period and were defined as an asthma-related accident and emergency (A&E) department visit or hospitalisation, or any oral corticosteroid (OCS) prescription with an asthma medical code recorded within ±2 weeks. A proportional hazard model was developed to evaluate the risk for subsequent exacerbations associated with the type of exacerbation (OCS vs. ED/hospitalisation).

Results A total of 211,807 patients with asthma were identified in CPRD during the study period. The mean age was 45 years and females made up 58% of the study population. Of these patients, 17,785 (8.4%) and 3,592 (1.7%) experienced ≥1 and ≥2 exacerbations, respectively during the follow-up period. The proportion of patients experiencing ≥1 or ≥2 exacerbations increased with severity and prior exacerbation frequency (Table 1). Among 1,900 patients with an asthma-related hospitalisation, 2.3%, 3.3%, and 3.8% experienced asthma-related readmissions within 30-, 60-, and 90-days, respectively. When limited to patients with more severe disease, the readmission rates increased significantly, up to three times in those with a history of ≥2 exacerbations. Compared to an OCS defined exacerbation, an A&E visit or hospital admission was associated with a 30% greater risk for any subsequent exacerbation (HR = 1.3, 95% CI 1.15–1.44), after adjusting for gender, disease severity, atopy, and exacerbation history.

Conclusion Asthma exacerbations remain a burden for patients with severe asthma or a history of frequent exacerbations. Additionally, patients should be managed carefully after an asthma exacerbation as they are at higher risk for subsequent exacerbations and readmission. (GSK-funded; WEUSKOP7092).