Combined value of exhaled nitric oxide and blood eosinophils in chronic airway disease: the Copenhagen General Population Study

Abstract

We investigated whether the combination of increased exhaled nitric oxide fraction () level and blood eosinophil count had an additive value in chronic airway disease in the general population.We included 4677 individuals aged 20-100 years from the Copenhagen General Population Study. Based on pre- and post-bronchodilator spirometry, self-reported asthma and smoking history, participants were subdivided into healthy never-smokers (n=1649), healthy ever-smokers (n=1581), asthma (n=449), chronic obstructive pulmonary disease (COPD) (n=404), asthma-COPD overlap (ACO) (n=138) and nonspecific airflow limitation (n=456).Compared to individuals with <25 ppb and blood eosinophils <0.3×10 cells·L, age- and sex-adjusted odds ratios (95% CI) for wheezing were 1.54 (1.29-1.84) for individuals with ≥25 ppb or blood eosinophils ≥0.3×10 cells·L and 2.14 (1.47-3.10) for individuals with ≥25 ppb and blood eosinophils ≥0.3×10 cells·L Corresponding odds ratios were 1.13 (0.91-1.41) and 1.83 (1.20-2.79) for sputum production, 1.54 (1.22-1.94) and 3.26 (2.16-4.94) for asthma, 1.03 (0.80-1.32) and 0.67 (0.36-1.27) for COPD and 1.32 (0.88-1.96) and 2.14 (1.05-4.36) for ACO. Among individuals reporting respiratory symptoms, predicting the type of chronic airway disease did not differ between the two biomarkers and did not improve by combining them.Combination of and blood eosinophils may have an additive value in characterising chronic airway disease in the general population but still needs to be investigated further with regard to clinical application.

Different Relationships between FENO and COPD Characteristics in Smokers and Ex-Smokers

“…Those with three exacerbations (8 smokers and 13 ex-smokers) had a F E NO 50 of 11 (8,16) and 11 (8,15) ppb, respectively. Those with one or two exacerbations (49 smokers and 99 ex-smokers) had a F E NO 50 of 9 (8, 11) and 16 (14,18) ppb, respectively; and subjects with zero exacerbations (90 smokers and 251 ex-smokers) had a F E NO 50 of 9 (8,10) and 15 (14,17) ppb, respectively. Accordingly, in smokers there was no significant difference in F E NO 50 (p ¼ 0.469), but exsmokers did show a decrease in F E NO 50 when the exacerbations increased (p ¼ 0.008).…”

“…According to recent publications, both increased F E NO values [13,15,16], and non-increased F E NO values [17] are reported in ACO. IgE sensitisation is an important determinant of F E NO 50 both in population-based studies [18] and among subjects with asthma [19], yet it has been sparsely studied in COPD [20].…”

Scottish consensus statement on the role of FeNO in adult asthma

“…The presence of blood eosinophilia (>300 cells/µl) may be used to identify activity of T2 inflammation, although it may be normal in patients with raised sputum eosinophils. While FeNO alone provides sufficient accuracy for detecting T2 inflammation, the combination of FeNO and blood eosinophils further improves the strength of identifying T2 related inflammation in asthma 15 . By the same token a normal FeNO level in a patient who has stopped pre-existing ICS may be useful for undiagnosing asthma, especially when a normal value is obtained in conjunction with a negative bronchial challenge test 16 .…”

The efficacy of the combination of exhaled nitric oxide and blood eosinophil count in the diagnosis of asthma in China

“…In some studies, the researchers con rmed that these two biomarkers could be used to identify types of chronic respiratory diseases, but such studies were conducted in the general population. [16,17] Signi cant differences in FeNO and B-Eos count between asthmatic and healthy people can lead to overestimating the diagnostic accuracy of these two biomarkers. Meanwhile, some conclusions have been drawn on the basis of selected asthma patients such as adolescents and young adults [18] and might not be applicable to all adult patients.…”

“…Meanwhile, some conclusions have been drawn on the basis of selected asthma patients such as adolescents and young adults [18] and might not be applicable to all adult patients. In addition, the diagnosis of asthma in some studies was self-reported (mainly based on non-speci c patient symptoms), [17,19] which led to underdiagnosis of asthma because patients inadequately reported respiratory symptoms to their doctors. [5] Importantly, due to the lack of widely accepted de nitions of high FeNO levels and high B-Eos counts, the combination of these two biomarkers for the diagnosis of asthma is worthy of further study.…”