Minimal effect of inhaled corticosteroids (ICS) on blood eosinophil count in steroidnaïve COPD patients

Robust biomarkers for COPD may help direct patient-specific therapy, e.g. sputum eosinophilia in COPD patients predicts clinical response to ICS (Brightling C.E. et al. Thorax 2005:60:193-8). Peripheral blood eosinophil count has also been proposed as a biomarker to direct corticosteroid therapy during COPD exacerbations. We wished to quantify the extent to which ICS affected peripheral blood eosinophil count and conducted posthoc analysis on two randomised, double-blind, placebo-controlled intervention studies in stable, steroidnaïve COPD subjects. RES106087 (NCT00379730) was a 6 wk study comparing placebo (n=44) with oral prednisolone (n=45) (Lomas D.A. et al. Eur Respir J 2009:34:95-102). SCO104925 (NCT00358358) was a 12 wk study comparing placebo (n=42), fluticasone propionate (FP)/salmeterol (SAL) 500/50mcg combination (n=39) and its individual components, FP 500mcg (n=42) and SAL 50mcg (n=38). As expected, oral prednisolone caused a mean reduction of 71 cells/microliter (SE 21.9) in blood eosinophils at 4 weeks that returned to baseline following washout. ICS caused a mean 55.3 cells/microliter (26.9) reduction at week 6 and a 34.2 cells/microliter (20.7) reduction at week 12. These data suggest there is minimal effect of ICS on blood eosinophil levels in COPD and that concurrent medication exclusions in phenotyping efforts should focus on oral corticosteroids. (Figure Presented).