Fractional exhaled nitric oxide (FENO) has been proposed as a diagnostic test of asthma, recently reaffirmed by the ATS Guideline on Exhaled Nitric Oxide Levels (FENO) Use.This 10-yr follow up of the Environment and Childhood Asthma Study in Oslo included 616 children of prospective birth cohort. Both FENO (single breath technique) and skin prick test (SPT) were measured in 331 children.
FENO was elevated in children with asthma (9.6 p.p.b.) compared with healthy children (5.8 p.p.b.).
FENO was highest among children with current allergic asthma (asthma and positive SPT) (14 p.p.b.). In contrast, children with non-allergic asthma (6 p.p.b) had comparable FENO levels to healthy children.
Allergic sensitization was most closely associated with FENO.
A FENO cut-off value of 20.4 p.p.b. had a high specificity (0.97), but a low sensitivity (0.41) for current allergic asthma.
High FENO levels were associated with current allergic asthma and not with current asthma without allergic sensitization.
However, a 2012 study in the journal Thorax, showed that tailoring of asthma treatment based on FeNO levels was ineffective in improving outcomes in children and adults.
References:
Diagnostic value of exhaled nitric oxide in childhood asthma and allergy. Sachs-Olsen C, Lødrup Carlsen KC, Mowinckel P, Håland G, Devulapalli CS, Munthe-Kaas MC, Carlsen KH. Pediatr Allergy Immunol. 2010 Feb;21(1-Part-II):e213-e221. doi: 10.1111/j.1399-3038.2009.00965.x.
ATS Guideline on Exhaled Nitric Oxide Levels (FENO) Use
Daily exhaled nitric oxide measurements ($17 each) could predict asthma exacerbations in children. Allergy, 2011.
In the UK, FeNO is used in primary practice to guide ICS initiation, dosing and identify poor ICS adherence http://buff.ly/1aHKopT
Image source: NioxMino.