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- Title
External validation of blood eosinophils, FeNO and serum periostin as surrogates for sputum eosinophils in asthma.
- Authors
Mincheva, Roxana
- Abstract
Asthma is a disease that consists of many sub-phenotypes. There is still a persistent need for accessible and reliable markers which can preferably reflect the response to the treatment and predict asthma exacerbations. Sputum eosinophilia is a key asthma indicator but inducing sputum is cumbersome and frequently unsuccessful. Blood eosinophils, exhaled nitric oxide fraction (FeNO) and serum periostin have all been entertained as surrogate markers but their relationship with asthma phenotypes have not been validated. The present study ventures to explore these relationships in two different cohorts of asthmatics.Asthma was described in two cross-sectional studies: 1) an external validation cohort of mild and moderate asthmatics (n=110); and 2) a replication cohort with more severe asthmatics (n=37). Measurements of lung function, atopy, sputum eosinophils as well as peripheral blood eosinophils, FeNO and serum periostin were obtained for all participants. Receiver operating characteristic (ROC) curve analysis was performed on the last three of those parameters, separately or together, to look for the most exact marker that reflected sputum eosinophil count of ≥3%. In the external validation cohort, both blood eosinophils and FeNO correlated moderately with sputum eosinophils ≥3% (r=0.59 and r=0.52, respectively; p<0.001) but no correlation was found with serum periostin. Diagnostic accuracy of blood eosinophils (described as area under the ROC curve (AUC)) was 89% and cut-off value of ≥0.27×109 per L achieved 78% sensitivity and 91% specificity. FeNO was also discriminative between eosinophilic and non-eosinophilic inflammation with an AUC of 78%. Optimal sensitivity and specificity, respectively, of 63% and 92%, was achieved at an FeNO ≥42ppb. Serum periostin did not exhibit satisfactory accuracy. In the replication cohort blood eosinophils could detect eosinophilic inflammation in 85%, while periostin did not achieve such accuracy (AUC of 54%).In conclusion, blood eosinophils could be used as an accurate surrogate marker for sputum eosinophilia in asthma with different severity which can be beneficial to the disease management. FeNO and periostin can be used to complement asthma phenotyping.
- Publication
Breathe, 2015, Vol 11, Issue 3, p230
- ISSN
1810-6838
- Publication type
Academic Journal
- DOI
10.1183/20734735.113115