Background: The risk factors for asthma exacerbations are not fully understood. The aim of this study was to determine the epidemiological and clinical characteristics of patients who experience asthma exacerbations. We also assessed potential triggers of exacerbations and possible predictors of hospitalization.
Methods: A retrospective, noninterventional cohort study was conducted in adult patients who attended the emergency department of a tertiary hospital with an asthma exacerbation during 2014.
Results: The study population comprised 831 patients (888 events). Most episodes occurred in January and May. Respiratory infection was the trigger in 523 events. In 34.21% of cases, the eosinophil count was ≥260/mm³ (≥400/mm³ in 20.7%), which was significantly associated with allergic asthma (P<.0001). The risk factors for hospitalization were older age (OR, 1.58; 95%CI, 1.46-1.71), no previous diagnosis of asthma (OR, 1.40; 95%CI, 1.06-1.86), poorly controlled asthma (OR, 1.78; 95%CI, 1.10-2.88), respiratory infection (OR, 2.65; 95%CI, 1.95-3.62), and severe exacerbation with more treatment requirements. The rate of hospitalization was significantly lower in patients with ≥400 eosinophils/mm³ (P<.001).
Conclusion: Older age, absence of a previous asthma diagnosis, uncontrolled disease, and concomitant chronic obstructive pulmonary disease are frequent among patients presenting at the emergency department with asthma exacerbations. Various features were associated with a higher risk of admission. Blood eosinophilia should be considered a marker of asthma, but not a predictor of hospitalization.

Key words: Asthma, Exacerbation, Risk of hospital admission, Eosinophilia