Blood eosinophil counts for the prediction of the severity of exercise-induced bronchospasm in asthma.
It has been suggested that airway eosinophilic inflammation is associated with the severity of exercise-induced bronchospasm (EIB). Blood eosinophils are known to be an indirect marker of airway inflammation in asthma. The aim of this study is to investigate that a simple and easy blood test for blood eosinphil counts may predict the severity of EIB in asthma. Seventy-seven men with perennial asthma (age range 18-23 years) were included. Lung function test, skin prick test, and blood tests for eosinophils counts and total IgE levels were performed. Methacholine bronchial provocation test and, 24 h later, free running test were carried out. EIB was defined as a 15% reduction or more in post-exercise FEV1 compared with pre-exercise FEV1 value. Atopy score was defined as a sum of mean wheal diameters to allergens. EIB was observed in 60 (78%) of 77 subjects. Asthmatics with EIB showed significantly increased percentages of eosinophils (P<0.01), log eosinophil counts (P<0.001), and atopy scores (P<0.05) and decreased log PC20 values (P < 0.05) compared with asthmatics without EIB. Asthmatics with eosinophils of > 700 microl(-1) (36.9 +/- 12.7%) had significantly greater maximal % fall in FEV1 after exercise than asthmatics with eosinophils of < 350 microl(-1) (24.7 +/- 16.6%, P <0.05). Blood eosinophil counts > 350 microl(-1) yielded the specificity of 88% and positive predictive value of 93% for the presence of EIB. When a multiple regression analysis of maximal % fall in FEV1 according to log eosinophil counts, log PC20, log IgE and atopy score was performed, only blood eosinophil counts were significant factor contributing to the maximal % fall in FEV1 after exercise. These findings not only suggest that a simple blood test for eosinophils may be useful in the prediction of the severity of EIB, but also reinforce the view that airway eosinophilic inflammation may play a major role in EIB in asthma.
Koh
Y I
YI
Department of Internal Medicine, Chonnam National University Medical School and Research Institute of Medical Science, Kwangju, Korea.
Choi
S
S
D000293:Adolescent; D000328:Adult; D001250:Asthma, Exercise-Induced / Q000097:blood / Q000503:physiopathology*; D015415:Biomarkers / Q000097:blood; D001986:Bronchial Spasm / Q000097:blood / Q000175:diagnosis*; D016085:Bronchoconstrictor Agents; D016009:Chi-Square Distribution; D004804:Eosinophils / Q000473:pathology*; D005080:Exercise Test; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007958:Leukocyte Count; D008297:Male; D016210:Methacholine Chloride; D012044:Regression Analysis; D012882:Skin Tests
D015415:Biomarkers; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D007073:Immunoglobulin E