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Table 2 Likelihood ratio at different cut-off points (n = 160); unit of FENO is parts per billion; LR+ is positive likelihood ratio, LR- is negative likelihood ratio

From: 'Diagnosing Asthma in General Practice with Portable Exhaled Nitric Oxide Measurement – Results of a Prospective Diagnostic Study: FENO ≤ 16 ppb better than FENO ≤ 12 ppb to rule out mild and moderate to severe asthma

Asthma diagnoses

FENO

LR+ (95%CI)

LR- (95%CI)

Borderline BHR, mild BHR, moderate to severe BHR, positive bronchodilator reversibility (n = 75)

> 12

1.12 (0.96–1.30)

0.62 (0.32–1.21)

 

> 16

1.47 (1.12–1.93)

0.58 (0.39–0.86)

 

> 20

1.55 (1.12–2.14)

0.65 (0.47–0.91)

 

> 35

1.94 (1.09–3.48)

0.81 (0.68–0.98)

 

> 46

4.53 (1.96–10.49)

0.73 (0.62–0.86)

 

> 76

not calculable

not calculable

Mild BHR, moderate to severe BHR, positive bronchodilator reversibility (n = 58)

> 12

1.19 (1.03–1.37)

0.42 (0.18–0.97)

 

> 16

1.76 (1.37–2.26)

0.38 (0.22–0.64)

 

> 20

1.76 (1.30–2.39)

0.53 (0.36–0.79)

 

> 35

2.17 (1.25–3.77)

0.77 (0.62–0.95)

 

> 46

4.10 (2.02–8.36)

0.70 (0.57–0.86)

 

> 76

not calculable

not calculable