Ethnic Differences in Exhaled Nitric Oxide (FeNO) Before, During, and After an Asthma Exacerbation in Children with Asthma

Studies have found African American (AA) asthmatics to be less responsive to systemic and inhaled glucocorticoid (GC) therapy, although this finding remains controversial. 131 children (67 Caucasians, 37 Hispanics, 27 AA’s) with moderate asthma had exhaled nitric oxide (FeNO) and spirometry measured before, during and after an acute asthma exacerbation (following a course of prednisone). At baseline, there was no difference in lung function between Caucasians and AA’s. AA’s were more atopic (15.5±1.5 vs. 9.8±1.1 positive SPT; p=0.005), required higher dose inhaled GC (998±126 vs. 676±85 mcg/d; p=0.04) and had higher FeNO levels (42±5 vs. 26±3 ppb; 0.008). Hispanics compared to Caucasians had better lung function but similar FeNO levels. During an acute exacerbation, compared to Caucasians, AAs had the greatest increase in FeNO (79±9 vs. 49±6; p=0.006), while there was no difference in lung function between the groups. Following prednisone therapy, AA’s had the highest FeNO levels (40±5 vs. 25±3;p=0.01) and fewer had a positive FeNO response (level falling to ≤24 ppb; 71% vs. 30%.; p=0.003). Hispanics had the greatest improvement in both FEV1 and FEF25-75 following prednisone therapy. Compared to Caucasian children with moderate persistent asthma, AA children had higher FeNO levels at baseline, during an acute exacerbation and following a course of prednisone. In addition, fewer AA’s had a positive FeNO response to prednisone. This suggests that AA children have a greater degree of allergic inflammation at baseline, have a greater inflammatory response during an asthma exacerbation, and have a blunted response to prednisone therapy.