Risk factors associated with frequent exacerbations in asthma

Background

Asthma is a chronic airway inflammatory disease with various degrees of severity. Exacerbations are commonly seen in uncontrolled asthma and their treatment involves oral corticosteroids use with a lot of side effects.

Objective

The aim of the study was to identify easily available predictors for future exacerbations in patients with asthma.

Methods

This is a prospective study on 250 consecutive patients with asthma with a successful sputum induction. Exacerbation rate in the following year was assessed by telephone interview. Logistic regression was used to test the relationship between the binary outcomes (<1 or ≥1 exacerbation, <2 or ≥2 exacerbations) and a set of covariates including demographic, clinical, functional and inflammatory characteristics such as FeNO, sputum and blood cell counts. The results were then applied and validated in a new cohort of 1450 patients.

Results

Sputum and blood eosinophils were able to identify patients presenting ≥1 or ≥2 exacerbations with the same discriminative power (AUC:0.65 and 0.64 respectively). The multiple regression analysis identified that exacerbations in the previous year (OR = 9.3), treatment with high doses ICS (OR = 27.1), blood eosinophils (cells/mm³, OR = 1.8) and FEV₁/FVC (OR = 0.93) were independent predictors of exacerbations in the year following the visit with an AUC of 0.93 for this model. Frequent exacerbations (≥2) were also predicted by exacerbations in the previous year (OR = 10.5), treatment with high doses ICS (OR = 39.2) and blood eosinophils (OR = 3.5) with an AUC of 0.95 for the model.

Conclusion

Blood and sputum eosinophils have similar predictive value for future exacerbations. Prediction could be improved by combining this information with lung function, ICS dose and history of previous exacerbations.