Figure 1.
Study design. ACO, asthma–COPD overlap; FAO, fixed airflow obstruction.
Table 1.
Clinical and laboratory characteristics in asthma, asthma + smoking, asthma + FAO, and ACO groups.
| Variable | Asthma (n = 56) | Asthma + Smoking (n = 15) | Asthma + FAO (n = 34) | ACO (n = 15) | P-value |
|---|---|---|---|---|---|
| Age (years) | 45.0 ± 15$,& | 53.0 ± 16 | 54 ± 15* | 64.0 ± 8.0* | <0.01y |
| Male, n (%) | 11 (19.6)#,& | 14 (93.3)*,$ | 4 (11.8)#,& | 14 (93.3)*,$ | <0.01z |
| BMI (kg/m2) | 22.3 ± 2.6 | 22.7 ± 2.1 | 23.0 ± 2.7 | 22.0 ± 3.3 | 0.57y |
| Smoking, n (%) | 0#,& | 15 (100.0)*,$ | 0#,& | 15 (100.0)*,$ | <0.01z |
| Allergic history, n (%) | 32 (57.1) | 7 (46.7) | 20 (58.8) | 7 (10.6) | 0.78t |
| Diabetes, n (%) | 6 (10.7) | 1 (6.7) | 5 (14.7) | 0 | 0.43z |
| Hypertension, n (%) | 8 (14.4) | 1 (6.7) | 4 (11.8) | 2 | 0.89z |
| OSA, n (%) | 11 (19.6) | 6 (40.0) | 10 (29.4) | 1 (6.7) | 0.12z |
| GERD, n (%) | 15 (26.8) | 2 (13.3) | 10 (29.4) | 7 (46.7) | 0.24z |
| Serum total IgE (lU/mL) | 158.1 [130.0–356.4] | 251.4 [70.0–460.6] | 154.5 [54.3–464.3] | 216.7 [66.3–462.5] | 0.88x |
| FeNO (ppb) | 34 [19–52] | 25 [17–39] | 39 [29–61] | 29 [22–48] | 0.22x |
| Blood eosinophil (cells/μL) | 220.4 [130.0–356.4] | 310.5 [134.2–461.1] | 205.5 [121.8–427.8] | 477.9 [170.1–92.0] | 0.06x |
Table 2.
Pulmonary function indices in asthma, asthma + smoking, asthma + FAO and ACO groups.
| Parameter | Asthma (n = 56) | Asthma + Smoking (n = 15) | Asthma + FAO (n = 34) | ACO (n = 15) | P-value |
|---|---|---|---|---|---|
| FEV1% predicted (%) | 79 [67–88]$ | 88 [75–95]$ | 58 [45–66]*, # | 72 [58–79] | <0.01 |
| FEV1 improvement (mL) | 80 [0–150] | 80 [0–130] | 100 [70–160] | 170 [70–270] | 0.06 |
| FEV1 improvement (%) | 4 [0–8]$,& | 3 [0–6]$ | 8 [5–11]*, # | 9 [4–16]* | <0.01 |
| FVC% predicted (%) | 82 [71–93]$ | 86 [75–91] | 72 [63–81]* | 81 [72–85] | 0.02 |
| FEV1/FVC ratio (%) | 76 [73–80]$,& | 78 [74–79]$,& | 64 [58–67]*,# | 64 [60–68]*,# | <0.01 |
| PEF% predicted (%) | 62 [51–71]$ | 66 [62–76]$ | 43 [35–52]*,# | 56 [33–71] | 0.09 |
| FEF25%-75% predicted (%) | 66 [52–74]$ | 80 [64–102]$ | 33 [22–40]*,# | 49 [37–65] | <0.01 |
1 ACO, asthma–chronic obstructive pulmonary disease overlap; FAO, fixed airflow obstruction; FEF25–75%, forced expiratory flow at 25%–75% of FVC; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; PEF, peak expiratory flow.
Table 3.
Plasma inflammatory cytokine levels in asthma, asthma + smoking, asthma + FAO, and ACO groups.
| Asthma (n = 56) | Asthma + Smoking (n = 15) | Asthma + FAO (n = 34) | ACO (n = 15) | P-value | |
|---|---|---|---|---|---|
| IFN-α (ng/L) | 0.53 [0.4–1.0] | 0.9 [0.4–1.5] | 0.4 [0.4–1.4] | 1.1 [0.6–2.3] | 0.12 |
| IFN-γ (ng/L) | 5.3 [5.1–10.0] | 6.1 [5.1–12.0] | 5.1 [5.1–10.0] | 9.0 [7.0–12.4] | 0.26 |
| IL-1β (ng/L) | 1.4 [0.8–2.7]& | 1.6 [0.8–2.7] | 1.0 [0.81–2.7]& | 3.8 [2.7–4.8]*,$ | <0.01 |
| IL-4 (ng/L) | 19.7 [6.9–29.8] | 20.3 [15.0–32.8] | 18.1 [10.3–33.8] | 21.1 [11.8–29.9] | 0.66 |
| IL-12 (ng/L) | 37.5 [19.5–269.0] | 38.5 [22.6–283.1] | 33.2 [20.0–195.0] | 284.7 [52.8–373.6] | 0.054 |
| IL-13 (ng/L) | 7.2 [1.7–10.5] | 5.3 [1.7–12.1] | 6.1 [1.7–10.5] | 10.5 [1.7–48.4] | 0.27 |
| IL-17 (ng/L) | 6.8 [1.5–12.8]& | 8.5 [1.5–17.7] | 5.1 [1.5–10.0]& | 16.4 [6.9–26.5]*,$ | <0.01 |
| TNF-α (ng/L) | 7.6 [3.5–16.0]& | 12.9 [3.5–21.5] | 5.3 [3.5–17.2]& | 18.8 [10.2–23.0]*,$ | 0.01 |
1 ACO, asthma–chronic obstructive pulmonary disease overlap; FAO, fixed airflow obstruction; IFN-α/IFN-γ, interferon alpha/gamma, IL, interleukin, TNF-α, tumour necrosis factor alpha.
Figure 2.
Plasma IL-1β concentrations across patient groups: asthma, Asthma+Smoking, Asthma+FAO, and ACO.
Figure 3.
Plasma IL-17 concentrations across patient groups: asthma, Asthma+Smoking, Asthma+FAO, and ACO.
Figure 4.
Plasma TNF-α concentrations across patient groups: asthma, Asthma+Smoking, Asthma+FAO, and ACO.