Both fractional exhaled nitric oxide and sputum eosinophil were associated with uncontrolled asthma

Figures & data

Table 1 Demographic and baseline characteristics of the patients

Demographic parameters	All participants (N=69)
Mean age, years (SD)	58.86 (15.2)
Range	18–85
Males, n (%)	40 (57.97)
Race, n (%)
Chinese	69 (100)
Mean height, cm (SD)	160 (9.04)
Range	136–174
Mean weight, kg (SD)	58.7 (8.83)
Range	44.5–84
Mean body mass index, kg/m^2 (SD)	22.89 (3.22)
Range	16.71–32.98
Smokers, n (%)	27 (39.13)
Pack-years, years (SD)	45 (31.47)
Allergic rhinitis, n (%)	8 (11.59)

Note: N refers to the total population; n refers to the subgroup population.

Table 2 Spirometry results for the patients

Variable postbronchodilator	All participants (N=69)
FVC (L), mean (SD)	3.04 (0.93)
FEV1 (L), mean (SD)	2.03 (0.6)
FEV1% predicted, mean (SD)	82.01 (11.94)
FEV1/FVC (%), mean (SD)	67.38 (8.71)
PEF (L/min), mean (SD)	5.39 (1.78)
PEF% predicted, mean (SD)	78.42 (17.44)
MMEF, mean (SD)	1.38 (0.52)
MMEF% predicted, mean (SD)	40.16 (18.89)
MEF50% (L/s), mean (SD)	1.75 (0.75)
MEF50% predicted, mean (SD)	46.95 (21.12)
MEF25% (L/s), mean (SD)	0.61 (0.28)
MEF25% predicted, mean (SD)	45.92 (20)

Abbreviations: FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; PEF, peak expiratory flow; MMEF, maximum mid-expiratory flow; MEF, maximal expiratory flow.

Table 3 FeNO levels and induced sputum results for the patients

Variables	All participants (N=69)
FeNO level (ppb)	47 (24, 87)
Eosinophil (%)	5.78 (1.95, 19.3)
Neutrophil (%)	75.2 (19.26)
Macrophage (%)	5.23 (2.24, 14.15)

Note: Values are expressed as median (interquartile range) or mean (SD).

Abbreviation: FeNO, fractional exhaled nitric oxide.

Table 4 FeNO levels and sputum neutrophilic percentage results for the patients

Variables	S-eosinophil (n=52)	S-noneosinophil (n=17)	p-value
Mean age, years	56.12 (15.37)	67.24 (11.41)	0.412
Males, n (%)	32 (61.54)	8 (47.06)	0.294
BMI, kg/m^2	22.87 (3.86)	22.96 (2.81)	0.566
Smokers, n (%)	22 (42.31)	5 (29.41)	0.344
Postbronchodilator FEV1% predicted	80.62 (8.53)	86.26 (18.68)	0.06
Postbronchodilator FEV1 (L)	2.12 (0.6)	1.74 (0.51)	0.329
Postbronchodilator FEV1/FVC (%)	66.69 (8.77)	69.46 (8.44)	0.747
PEF (L/min)	5.76 (1.74)	4.25 (1.4)	0.12
FeNO level, ppb	49 (29, 95)	27 (19, 48)	0.011
Neutrophilic%	71.12 (20)	87.67 (9.11)	0.012
Macrophage%	5.15 (2.05, 13.4)	9.6 (2.35, 17.76)	0.592

Notes: S-eosinophil refers to sputum eosinophil count ≥2.5%; S-noneosinophil refers to sputum eosinophil count <2.5%. Significant p-value <0.05 are shown in bold.

Abbreviations: BMI, body mass index; FeNO, fractional exhaled nitric oxide; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; PEF, peak expiratory flow.

Table 5 Sputum eosinophil and neutrophil percentage result for the patients

Variables	F-eosinophilic (n=45)	F-noneosinophilic (n=24)	p-value
Mean age, years	54.98 (15.59)	66.13 (11.55)	0.262
Males, n (%)	27 (60)	13 (54.17)	0.64
BMI, kg/m^2 (SD)	22.32 (3.13)	23.96 (3.17)	0.829
Smokers, n (%)	16 (35.56)	11 (45.83)	0.405
Postbronchodilator FEV1% predicted	81.56 (12.58)	82.3 (10.9)	0.908
Postbronchodilator FEV1 (L)	2.13 (0.55)	1.84 (0.66)	0.166
Postbronchodilator FEV1/FVC (%)	67.67 (8.89)	66.83 (8.53)	0.64
PEF (L/min)	5.64 (1.71)	4.91 (1.83)	0.766
Eosinophilic%	10.3 (3.8, 22.68)	2.75 (0.3, 8.35)	0.03
Neutrophilic%	70.93 (20.51)	83.2 (13.77)	0.049
Macrophage%	6.2 (2.13, 17.89)	5.17 (2.3, 12.34)	0.508

Notes: F-eosinophilic refers to FeNO level ≥32 ppb; F-noneosinophilic refers to FeNO level <32 ppb. Significant p-value <0.05 are shown in bold.

Abbreviations: BMI, body mass index; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; PEF, peak expiratory flow.

Figure 1 Scatter plots of relationship between sputum eosinophil, FeNO, BHR and bronchodilator reversibility.

Notes: (A) Correlation between sputum eosinophil percentage and PD₂₀ (mg). (B) Correlation between FeNO level and ΔFEV₁ (mL). (C) Correlation between sputum eosinophil percentage and ΔFEV₁ (mL). (D) Correlation between FeNO level and ΔFEV₁ (mL); Δ, improvement in FEV₁ after 400 μg of salbutamol. (E) Correlation between FeNO level and sputum eosinophil percentage.
Abbreviations: FeNO, fractional exhaled nitric oxide; BHR, bronchial hyperresponsiveness; FEV₁, forced expiratory volume in 1 second; PD₂₀, provocative dose.

Figure 2 ROC curve for sputum eosinophil percentage versus FeNO level (A) and FeNO level versus sputum eosinophil percentage (B).

Abbreviations: FeNO, fractional exhaled nitric oxide; ROC, receiver operating characteristic.