Obesity affects type 2 biomarker levels in asthma

Figures & data

Figure 1. Trial participants by disease severity and weight category

Table 1. Demographic and clinical characteristics overall and stratified by disease severity.

Variable	Overall n = 153	Mild asthma n = 51	Difficult asthma n = 102	p value*
Age, years	54 (44 − 64)	56 (32 − 64)	54 (46 − 63)	0.713
Female sex	91(59.5)	29(56.9)	62(60.8)	0.641
BMI, kg/m^2	31.1 (26.6 − 36.9)	25.3 (23.2 − 29.0)	33.9 (30.0 − 39.2)	<0.001
Smoking status:
Lifelong nonsmoker	87 (57.2)	37 (72.6)	50 (49.0)	0.014
Current smoker	9 (5.9)	2 (3.9)	7 (6.9)
Ex-smoker	56 (36.8)	12 (23.5)	45 (44.1)
Atopy	73 (47.7)	7 (13.7)	66 (64.7)	<0.001
Allergic rhinitis	104 (68.0)	33 (64.7)	71 (69.6)	0.540
Perennial rhinitis	66 (43.1)	16 (31.4)	50 (49.0)	0.038
Equivalent BDP ICS dose, mcg	1600 (800 − 2000)	400 (200 − 800)	1900 (1600 − 2000)	<0.001
OCS dose, mg	5 (5 − 10)	n/a	5 (5 − 10)	n/a
FeNO, ppb	22 (14 − 43)	22 (17 − 27)	23 (13 − 50)	0.308
Eosinophils, x10^9/L	0.2 (0.1 − 0.4)	0.1 (0.1 − 0.3)	0.3 (0.1 − 0.4)	0.020
Total IgE, kU/L	148 (32 − 372)	156 (132 − 560)	141 (31 − 386)	0.394

Reported as median (IQR) or no.(%) unless stated otherwise.

Abbreviations – BDP (beclomethasone diproprionate), BMI (body mass index), FeNO (fractional exhaled nitric oxide), ICS (inhaled corticosteroid), IgE (immunoglobulin E), IQR (interquartile range), OCS (oral corticosteroid), ppb (parts per billion).

* Mild vs Difficult asthma. Continuous variables compared using Mann-Whitney; categorical variables compared using chi-squared or Fisher’s exact.

Table 2. Comparison of all patients divided into BMI tertiles.

Variable	First Tertile n = 51	Second Tertile n = 51	Third Tertile n = 51	p value*	p value**
Age, years	56 (32 − 64)	58 (45 − 65)	54 (47 − 60)	0.701	0.791
Female sex	27 (52.9)	27 (52.9)	37 (72.5)	0.066	0.041
BMI kg/m^2	25.0 (23.2 − 26.7)	31.1 (29.5 − 32.9)	39.7 (36.8 − 43.9)	<0.001	<0.001
Smoking status:
Lifelong nonsmoker	38 (76.0)	25 (49.0)	24 (47.1)	0.026	0.010
Current smoker	2 (4.0)	4 (7.8)	3 (5.9)
Ex-smoker	10 (20.0)	22 (43.1)	24 (47.1)
Atopy	15 (29.4)	28 (54.9)	30 (58.8)	0.005	0.003
Allergic rhinitis	36 (70.6)	32 (62.7)	36 (70.6)	0.619	1.000
Perennial rhinitis	21 (41.2)	22 (43.1)	23 (45.1)	0.923	0.689
Equivalent BDP ICS dose, mcg	800 (400 − 1600)	1600 (1600 − 2000)	1600 (1600 − 2000)	<0.001	<0.001
OCS dose, mg	6.0 (5.0 − 11.0)	5.0 (5.0 − 10.0)	5.0 (5.0 − 10.0)	0.891	0.733
FeNO, ppb	25 (18 − 41)	23 (16 − 70)	18 (12 − 30)	0.024	0.014
Eosinophils, x10^9/L	0.2 (0.1 − 0.3)	0.3 (0.1 − 0.4)	0.2 (0.1 − 0.4)	0.643	0.799
Total IgE, kU/L	117 (32 − 243)	223 (68 − 720)	96 (20 − 334)	0.086	0.984
T2-high status	37 (72.5)	40 (81.6)	33 (64.7)	0.163	0.393

Reported as median (IQR) or no.(%) unless stated otherwise.

T2-high status defined as either: FeNO ≥ 25 ppb or eosinophils ≥ 0.15 x10^9/L.

Abbreviations – BDP (beclomethasone diproprionate), BMI (body mass index), FeNO (fractional exhaled nitric oxide), ICS (inhaled corticosteroid), IgE (immunoglobulin E), IQR (interquartile range), OCS (oral corticosteroid), ppb (parts per billion).

* All tertiles. Continuous variables compared using Kruskal-Wallis; categorical variables compared using chi-squared.

** First vs Third tertile. Continuous variables compared using Mann-Whitney; categorical variables compared using chi-squared or Fisher’s exact.

Table 3. Comparison of difficult-to-control asthma patients divided into BMI tertiles.

Variable	First Tertile n = 34	Second Tertile n = 34	Third Tertile n = 34	p value*	p value**
Age, years	58 (47 − 65)	58 (38 − 65)	52 (44 − 59)	0.122	0.046
Female sex	24 (70.6)	13 (38.2)	25 (73.5)	0.004	0.787
BMI, kg/m^2	28.7 (26.8 − 30.1)	33.9 (32.8 − 35.7)	41.9 (38.9 − 46.9)	<0.001	<0.001
Smoking status:
Lifelong nonsmoker	21 (61.8)	9 (26.5)	20 (58.5)	0.022	0.586
Current smoker	1 (2.9)	3 (8.8)	3 (8.8)
Ex-smoker	12 (35.3)	22 (64.7)	11 (32.4)
Atopy	21 (61.8)	22 (64.7)	23 (67.6)	0.879	0.612
Allergic rhinitis	22 (64.7)	21 (61.8)	28 (82.4)	0.136	0.099
Perennial rhinitis	17 (50.0)	15 (44.1)	18 (52.9)	0.760	0.808
Equivalent BDP ICS dose, mcg	2000 (1600 − 2400)	1700 (1600 − 2000)	1800 (1600 − 2000)	0.696	0.415
OCS dose, mg	5.0 (5.0 − 10.0)	8.75 (5.0 − 11.5)	5.0 (2.0 − 10.0)	0.264	0.299
FeNO, ppb	42 (20 − 66)	20 (12 − 55)	17 (12 − 38)	0.027	0.008
Eosinophils, x10^9/L	0.3 (0.2 − 0.5)	0.3 (0.1 − 0.5)	0.2 (0.1 − 0.3)	0.048	0.022
Total IgE, kU/L	162 (35 − 305)	147 (53 − 591)	89 (21 − 395)	0.601	0.371
T2-high status	32 (94.1)	28 (84.8)	21 (61.8)	0.003	0.001

Reported as median (IQR) or no.(%) unless stated otherwise.

T2-high status defined as either: FeNO ≥ 25 ppb or eosinophils ≥ 0.15 x10^9/L.

Abbreviations – BDP (beclomethasone diproprionate), BMI (body mass index), FeNO (fractional exhaled nitric oxide), ICS (inhaled corticosteroid), IgE (immunoglobulin E), IQR (interquartile range), OCS (oral corticosteroid), ppb (parts per billion).

* All tertiles. Continuous variables compared using Kruskal-Wallis; categorical variables compared using chi-squared.

** First vs Third tertile. Continuous variables compared using Mann-Whitney; categorical variables compared using chi-squared or Fisher’s exact.

Figure 2. (A) BMI for all patients categorised by T2-status. (B) BMI for difficult-to-control patients categorised by T2-status. (C) FeNO for all patients by BMI tertile. (D) FeNO for difficult-to-control patients by BMI tertile. (E) Eosinophils for all patients by BMI tertile. (F) Eosinophils for difficult-to-control patients by BMI tertile.

Figure 3. Negative correlation between log-transformed FeNO and BMI.