Increase in blood eosinophils during follow-up is associated with lung function decline in adult asthma.

BACKGROUND

Asthma is associated with accelerated rate of lung function (FEV1) decline.

OBJECTIVE

To determine predictive factors associated with FEV1 decline in adult asthma.

METHODS

A retrospective study was conducted in 229 asthmatics recruited from the University Asthma Clinic of Liege. Subjects had at least two visits with post-bronchodilation (post-BD) FEV1 and minimum one year between them. A multivariable linear regression analysis was conducted in order to come up with factors associated with lung function decline.

RESULTS

Post-BD FEV1 decline in % predicted. y-1 was 0.2 (95%CI -2.0 to 2.8) in the overall population. Our population was made up of mild to moderate asthmatics [1] for 58%, aged 50 (41-60) years old, 62% were female and 59% were atopic. Median ICS dose was 1000 μg beclomethasone equivalent (CFC)/day with 81% treated at baseline. Time between visits was 46.8 ± 32.1 months. The univariate linear regression analysis revealed a negative association between % predicted FEV1 decline and baseline ACQ (p < 0.0001) and blood eosinophils (% and/mm3) (p < 0.0001 and p < 0.0001). A positive association was found between % predicted FEV1 decline and baseline pre-BD FEV1 (mL) values (p = 0.001), blood neutrophils (%) (p = 0.02), change in blood eosinophils (%) (p < 0.0001), time between visits (months) (p < 0.0001). The predictive variables for accelerated decline highlighted by the multivariable analysis (r2 = 0.39) were change in blood eosinophils (%) over time (p = 0.002) and time between visits (months) (p < 0.0001).

CONCLUSION

These findings highlight a new value for blood eosinophil counts as their increase over time predicts greater lung function decline in asthma.