Bronchiectasis phenotyping with serum eosinophil percent maximizes clinical benefit of inhaled steroids

A new study found that a baseline eosinophil count of >=3.5% might serve as an indicator to enhance the effectiveness of inhaled corticosteroids in preventing bronchiectasis exacerbation. The therapeutic effect of ICS may be maximized by phenotyping bronchiectasis with baseline blood eosinophil count. The study results were published in The Clinical Respiratory Journal. 

Bronchiectasis is one of the commonest suppurative respiratory diseases, caused due to airway insult predisposing circumstances that lead to airway damage, chronic or recurring infections, and airway destruction. Inhaled corticosteroids are generally used because of their potential local anti-inflammatory effects and minimal systemic side effects. Phenotyping of airway diseases helps to personalize the treatment. Eosinophilic phenotyping is one of the markers of bronchiectasis for ICS treatment. As there is uncertainty in the literature, researchers conducted a study to find out the exact predictive biomarker and the optimal cut-off that might define the clinical benefit from ICS in bronchiectasis. 

A retrospective case–control study was conducted at Queen Mary Hospital, a major regional hospital and tertiary respiratory referral center in Hong Kong, including 140 Chinese patients with non-cystic fibrosis (CF) bronchiectasis, to investigate the exacerbation risks of bronchiectasis among ICS users and nonusers with different baseline eosinophil counts. Patients with bronchiectasis but not using ICS were taken as the control group. The primary outcome was bronchiectasis exacerbation within 1 year of the follow-up period.

Key findings: 

• There was a significantly lower risk to develop bronchiectasis exacerbation in ICS users with an adjusted odds ratio (OR) of 0.461.
• Univariate logistic regression was performed for different cut-offs of blood eosinophil count (by percentage) from 2% to 4% (with a 0.5% grid each time).
• Baseline eosinophil 3.5% was found to be the best cut-off among all with an adjusted OR of 0.138 (95% CI = 0.023–0.822, p-value = 0.030).

Thus, A baseline blood eosinophil level of ≥3.5% may serve as a predictor of how well ICS will work to keep bronchiectasis patients from exacerbating their condition.

Further reading: Blood eosinophil percentage as a predictor of response to inhaled corticosteroid in bronchiectasis.  https://doi.org/10.1111/crj.13624