Table 5. Comparisons of pulmonary function tests according to severity of asthma in children.

NAEPP classification		Mild intermittent	Mild persistent	Moderate/severe persistent	Overall P value*	Trend P value
FEV1, % predicted
	Prebronchodilator	91.52 (79.21–105.75)	91.59 (77.57–108.15)	79.61 (57.86–109.53)	< 0.001	< 0.001
	Postbronchodilator	97.54 (85.08–111.83)	97.06 (83.90–112.30)	82.01 (60.13–111.86)	< 0.001	< 0.001
FVC, % predicted
	Prebronchodilator	97.65 (85.34–111.74)	98.00 (83.88–114.49)	89.81 (71.16–113.35)	< 0.001	< 0.001
	Postbronchodilator	99.21 (86.9–113.28)	98.96 (85.19–114.97)	89.68 (71.29–112.81)	< 0.001	< 0.001
FEV1/FVC (%)
	Prebronchodilator	93.72 (84.85–103.52)	93.37 (84.09–103.69)	88.62 (74.43–105.53)	< 0.001	< 0.001
	Postbronchodilator	98.31 (89.31–108.23)	98.08 (90.38–106.44)	91.45 (76.91–108.74)	< 0.001	< 0.001
MMEF, % predicted
	Prebronchodilator	78.14 (56.89–107.32)	77.14 (55.67–106.87)	64.38 (37.47–110.60)	0.001	< 0.001
	Postbronchodilator	101.81 (74.96–138.28)	95.79 (70.10–130.89)	72.32 (43.46–120.34)	< 0.001	< 0.001
DFEV1 (L)		0.196 (0.002–19.522)	0.1827 (0.003–12.775)	0.254 (0.003–20.671)	< 0.001	< 0.001
DFEV1, % predicted		6.16 (2.59–14.67)	6.27 (2.61–15.07)	8.22 (3.36–20.09)	0.002	< 0.001
FeNO (ppb)		25.15 (12.47–50.73)	25.77 (12.4–53.53)	32.44 (15.3–68.76)	0.010	0.003
Methacholine PC20 (mg/mL)		2.10 (0.59–7.48)	2.49 (0.67–9.29)	1.04 (0.20–5.53)	< 0.001	< 0.001

Values are presented as geomean ± one standard deviation.

NAEPP, National Asthma Education and Prevention Program; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; MMEF, maximal mid-expiratory flow; FeNO, fractional exhaled nitric oxide; ppb, parts per billion; PC20, cumulative methacholine dose that caused a 20% reduction in FEV1.

^*Kruskall-Wallis test.