Table 1. Characteristics of the subjects.
| Characteristics | Asthma (n = 49) | ACO (n = 40) | COPD (n = 41) | Overall P value* | Pairwise P value† | |||
|---|---|---|---|---|---|---|---|---|
| Asthma vs. ACO | Asthma vs. COPD | ACO vs. COPD | ||||||
| Mucus plugging | 29 (59) | 26 (65) | 17 (41) | 0.087 | 0.663 | 0.138 | 0.046 | |
| Mucus score | 1 (0, 6) | 2 (0, 5) | 0 (0, 1) | 0.006 | 0.749 | 0.012 | 0.002 | |
| Tree-in-bud appearance | 17 (35) | 21 (53) | 11 (27) | 0.056 | 0.131 | 0.496 | 0.024 | |
| Bronchiectasis | 4 (8) | 2 (1) | 4 (10) | 0.780 | 0.687 | 1.000 | 0.675 | |
| Goddard score | 0 (0, 0) | 12 (9, 12) | 12 (11, 12) | < 0.001 | < 0.001 | < 0.001 | 0.035 | |
| Age (yr) | 65 (54, 72) | 76 (66, 80) | 76 (69, 80) | < 0.001 | < 0.001 | < 0.001 | 0.974 | |
| Sex, male | 19 (39) | 35 (88) | 36 (88) | < 0.001 | < 0.001 | < 0.001 | 1.000 | |
| Body mass index (kg/m2) | 23.7 (20.6, 27.0) | 22.5 (19.8, 24.6) | 22.4 (20.3, 24.9) | 0.265 | 0.151 | 0.187 | 0.862 | |
| Childhood asthma | 9 (18) | 1 (3) | 0 (0) | 0.001 | 0.021 | 0.003 | 0.494 | |
| Allergic rhinitis | 17 (35) | 11 (28) | 6 (15) | 0.090 | 0.500 | 0.051 | 0.181 | |
| Chronic rhinosinusitis | 9 (19) | 3 (8) | 1 (2) | 0.039 | 0.212 | 0.019 | 0.359 | |
| Severe asthma | 10 (20) | 2 (15) | NA | 0.058 | NA | NA | NA | |
| Smoking history | < 0.001 | < 0.001 | < 0.001 | 0.712 | ||||
| Never smoker | 31 (63) | 0 (0) | 0 (0) | |||||
| Ex-smoker | 12 (24) | 37 (93) | 36 (85) | |||||
| Current smoker | 5 (10) | 3 (7) | 5 (12) | |||||
| Pack-years | 0 (0, 12) | 41 (31, 58) | 50 (36, 63) | < 0.001 | < 0.001 | < 0.001 | 0.180 | |
| ACQ | 1.8 (0.9, 3.0) | 0.4 (0.0, 1.0) | NA | NA | 0.002 | NA | NA | |
| ACT | 20 (13, 22) | 23 (21, 25) | NA | NA | < 0.001 | NA | NA | |
| mMRC | NA | 1.0 (1.0, 1.75) | 1.0 (0.0, 1.0) | NA | NA | NA | 0.086 | |
| COPD assessment test | NA | 7.0 (3.75, 14.0) | 5.0 (3.0, 11.0) | NA | NA | NA | 0.181 | |
| CMH | NA | 8 (22) | 7 (18) | NA | NA | NA | 0.776 | |
| Blood eosinophil count (cells/μL) | 151 (52, 391) | 209 (110, 465) | 168 (91, 227) | 0.219 | 0.250 | 0.827 | 0.064 | |
| Total IgE (I.U./mL) | 238 (55, 754) | 211 (88, 474) | 95 (26, 269) | 0.067 | 0.632 | 0.034 | 0.051 | |
| Positive specific IgE antibody | 2 (0, 13) | 1 (0, 7) | 0 (0, 11) | < 0.001 | 0.005 | < 0.001 | 0.330 | |
| Sputum eosinophils (%) | 1.8 (0, 9.9) | 2.5 (0, 5.3) | 0 (0, 0.8) | 0.053 | 0.992 | 0.023 | 0.030 | |
| Sputum neutrophils (%) | 95.3 (85.0, 97.0) | 93.0 (86.5, 98.1) | 99.0 (95.3, 99.8) | 0.099 | 0.967 | 0.034 | 0.076 | |
| FeNO (ppb) | 40.5 (18.0, 66.3) | 35.0 (21.8, 67.3) | 24.5 (17.0, 30.5) | 0.051 | 0.972 | 0.051 | 0.017 | |
| FEV1 (L) | 1.72 (1.39, 2.21) | 1.46 (1.03, 1.89) | 1.85 (1.22, 2.24) | 0.183 | 0.089 | 0.979 | 0.135 | |
| %FEV1 | 77.8 (65.3, 89.1) | 63.8 (44.6, 72.5) | 71.1 (51.0, 88.5) | 0.002 | < 0.001 | 0.147 | 0.075 | |
| FVC (L) | 2.38 (2.03, 3.08) | 2.76 (2.20, 3.67) | 3.35 (2.29, 3.82) | 0.009 | 0.112 | 0.002 | 0.147 | |
| %FVC | 91.3 (77.5, 101.7) | 88.9 (75.1, 104.5) | 101.6 (82.7, 117.6) | 0.011 | 0.962 | 0.005 | 0.015 | |
| FEV1/FVC | 71.6 (62.5, 78.3) | 55.3 (42.4, 62.0) | 53.9 (45.4, 63.9) | < 0.001 | < 0.001 | < 0.001 | 0.552 | |
| %FEF 25–75 | 37.6 (25.5, 51.6) | 21.4 (11.7, 28.9) | 20.8 (15.6, 30.0) | < 0.001 | < 0.001 | < 0.001 | 0.543 | |
| R5 (cmH2O/L/s) | 3.71 (2.91, 4.52) | 3.74 (2.67, 4.65) | 2.58 (2.11, 3.56) | 0.003 | 0.686 | 0.002 | 0.006 | |
| R20 (cmH2O/L/s) | 3.00 (2.44, 3.67) | 2.98 (2.14, 3.29) | 2.23 (1.84, 3.05) | 0.001 | 0.141 | < 0.001 | 0.021 | |
| R5–R20 (cmH2O/L/s) | 0.79 (0.45, 1.11) | 0.87 (0.60, 1.29) | 0.54 (0.26, 1.00) | 0.024 | 0.295 | 0.122 | 0.004 | |
| X5 (cmH2O/L/s) | −0.73 (−1.03, −0.41) | −0.93 (−2.72, −0.47) | −0.61 (−1.03, −0.26) | 0.079 | 0.076 | 0.489 | 0.041 | |
| Fres (Hz) | 9.28 (7.68, 12.52) | 12.90 (8.80, 18.72) | 10.30 (6.74, 14.25) | 0.045 | 0.015 | 0.839 | 0.066 | |
| ALX (cmH2O/L) | 3.26 (1.31, 5.29) | 5.02 (1.68, 23.24) | 2.49 (0.83, 5.84) | 0.065 | 0.043 | 0.724 | 0.043 | |
| Inhaled corticosteroid use | 37 (76) | 35 (88) | 6 (15) | < 0.001 | 0.183 | < 0.001 | < 0.001 | |
| LABA | 35 (71) | 36 (90) | 32 (78) | 0.087 | 0.036 | 0.628 | 0.226 | |
| LAMA | 0 (0) | 20 (50) | 35 (85) | < 0.001 | < 0.001 | < 0.001 | < 0.001 | |
| Biologic use | 4 (8) | 2 (5) | 0 (0) | 0.160 | 0.687 | 0.123 | 0.241 | |
| Benralizumab | 3 (6) | 1 (3) | 0 (0) | |||||
| Omalizumab | 1 (2) | 0 (0) | 0 (0) | |||||
| Dupilumab | 0 (0) | 1 (3) | 0 (0) | |||||
| Systemic corticosteroid use | 1 (2) | 0 (0) | 0 (0) | 1.000 | 1.000 | 1.000 | 1.000 | |
Data are shown as median (interquartile range) or frequency (percentage).
ACO, asthma-chronic obstructive pulmonary disease overlap; COPD, chronic obstructive pulmonary disease; ACQ, Asthma Control Questionnaire; ACT, Asthma Control Test; NA, not applicable; mMRC, Modified British Medical Research Council; CMH, chronic mucus hypersecretion; FeNO, fractional exhaled nitric oxide; FEF 25–75, forced expiratory flow at 25%–75% of forced vital capacity; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; R5 and R20, respiratory resistance at 5 and 20 Hz; R5–R20, the difference between R5 and R20; X5, respiratory reactance at 5 Hz; ALX, low-frequency reactance area; Fres, resonant frequency; LABA, long-acting β2-agonists; LAMA, long-acting muscarinic antagonists.
*Kruskal-Wallis test, †Mann-Whitney U test, or Fisher's exact test. Sputum analysis was performed in 32 asthmatic, 20 ACO, and 11 COPD patients.