Study of the correlations between fractional exhaled nitric oxide in exhaled breath and atopic status, blood eosinophils, FCER2 mutation, and asthma control in Vietnamese children.
BACKGROUND
Fractional exhaled nitric oxide (FENO) is a biomarker of airway inflammation in asthma. The measurement of FENO is utilized to assist in the diagnosis and treatment of children with asthma, especially for those treated with inhaled corticosteroids.


OBJECTIVE
The aims of this study were to evaluate the correlations between FENO and atopic status, blood eosinophil levels, FCER2 mutation, and asthma control in Vietnamese children.


METHODS
This was a prospective and descriptive study approved by the local Ethical Board. All children with uncontrolled asthma, seen in the National Hospital of Pediatrics (Hanoi, Vietnam), were included. Exhaled breath FENO, blood eosinophils, skin prick test, total IgE, asthma control test (ACT), and FCER2 gene polymorphism were performed at inclusion. They were followed up at 3 months to evaluate clinical status, FENO levels, and ACT.


RESULTS
Forty-two children with uncontrolled asthma with a mean age of 10±3 years (6-16 years) were included. The male/female ratio was 2.5/1. The mean FENO levels were 26±25 ppb. FENO was significantly higher in patients with a positive skin prick test for respiratory allergens (P<0.05). FENO was significantly correlated with blood eosinophil levels (r=0.5217;P=0.0004). Five of the 32 subjects (15.6%) had a mutation of FCER2 gene (rs28364072 SNP). In this group, the levels of FENO were highest (37±10 ppb;P<0.05). The levels of FENO were significantly decreased after 3 months of treatment (17±8 ppb vs 26±25 ppb;P<0.05). Significant correlations between inhaled corticosteroid doses and FENO levels occurred at 1 and 3 months (r=0.415,P=0.007;r=0.396,P=0.010; respectively). There were no correlations between FENO levels, ACT, and daily use of salbutamol. After 3 months, asthma remained uncontrolled in 22.2% of children.


CONCLUSIONS
The measurement of FENO levels is a useful and feasible tool to predict clinical, biological, and asthma control in Vietnamese children.
Department of Immunology, Allergology, and Rheumatology, National Hospital of Pediatrics, Hanoi, Vietnam.
Hanh
H
Nguyen-Thi-Bich
School of Medicine and Pharmacy, Vietnam National University Hanoi, Vietnam.
Huong
H
Duong-Thi-Ly
School of Medicine and Pharmacy, Vietnam National University Hanoi, Vietnam.
Vu Thi
VT
Thom
School of Medicine and Pharmacy, Vietnam National University Hanoi, Vietnam.
Nhung
N
Pham-Thi-Hong
School of Medicine and Pharmacy, Vietnam National University Hanoi, Vietnam.
Long Doan
LD
Dinh
Department of Immunology, Allergology, and Rheumatology, National Hospital of Pediatrics, Hanoi, Vietnam.
Huong
H
Le-Thi-Minh
Department of Medicine, Penn State University, Hershey, PA, USA.
Timothy John
TJ
Craig
Department of Medicine, Penn State University, Hershey, PA, USA; Department of Respiratory Diseases, Lam Dong Medical College, Dalat, Vietnam.
Sy
S
Duong-Quy
FCER2; FENO; ICS; asthma; eosinophils; nitric oxide
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