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Table 1 Sensitivity (sens), specificity (spec), positive predictive value (PPV) and negative predictive value (NPV) at different cut-off points (n = 160); unit of FENO is parts per billion

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

sens [%] (95%CI)

spec [%] (95%CI)

PPV [%] (95%CI)

NPV [%] (95%CI)

n

Borderline BHR mild BHR moderate to severe BHR positive bronchodilator reversibility

(n = 75)*

> 12

85 (76–92)

24 (16–34)

50 (41–58)

65 (47–79)

126

 

> 16

69 (58–79)

53 (42–63)

57 (46–66)

66 (54–76)

92

 

> 20

64 (53–74)

58 (47–77)

57 (47–67)

65 (53–74)

82

 

> 35

32 (25–42)

84 (74–90)

63 (47–77)

58 (49–67)

38

 

> 46

32 (23–43)

93 (85–97)

80 (63–91)

61 (52–69)

30

 

> 76

13 (7–23)

100 (96–100)

100 (72–100)

57 (49–65)

11

Mild BHR moderate to severe BHR positive bronchodilator reversibility

(n = 58)§

> 12

90 (79–95)

25 (17–34)

40 (32–49)

81 (64–91)

126

 

> 16

79 (67–88)

55 (45–64)

50 (40–60)

82 (72–90)

92

 

> 20

67 (54–78)

62 (52–71)

50 (39–61)

77 (67–85)

82

 

> 35

36 (25–49)

83 (75–89)

55 (40–70)

70 (61–77)

38

 

> 46

36 (25–49)

91 (84–95)

70 (52–83)

72 (63–79)

30

 

> 76

17 (10–29)

100 (96–100)

100 (72–100)

68 (60–75)

11

  1. *prevalence of asthma = 46.9%, prevalence of 'no asthma' = 53.1%
  2. § prevalence of asthma = 36,3%, prevalence of 'no asthma' = 63.7%