Table 1.
Epidemiological characteristics according to subtypes of subjects with mild-to-moderate airflow limitation identified by k-means clustering for k=5 clusters
| N | All
|
COPD-overlap
|
COPD
|
Asthmatic
|
Near-normal
|
Asthmatic-overlap
|
P-value |
|---|---|---|---|---|---|---|---|
| 2,140 | 586 | 37 | 392 | 232 | 893 | ||
| FEV1 % predicted | 80.9±12.1 | 80.3±10.9 | 80.5±13.3 | 77.8±9.7 | 101.5±7.9 | 77.3±8.9 | <0.001 |
| BMI, kg/m2 | 23.6±2.8 | 23.6±2.7 | 23.9±2.8 | 23.4±2.9 | 23.2±2.5 | 23.7±2.9 | 0.047 |
| Self-reported wheezing | 0.002 | ||||||
| Yes | 352 (16) | 89 (15) | 3 (8) | 77 (20) | 21 (9) | 162 (18) | |
| No | 1,788 (84) | 497 (85) | 34 (92) | 315 (80) | 211 (91) | 731 (82) | |
| Age, years | 63.7±11.7 | 64.5±8.7 | 68.1±6.7 | 45.7±8.6 | 72.1±7.2 | 68.6±6.8 | <0.001 |
| ≥20 and <30 | 29 (1) | 0 (0) | 0 (0) | 29 (7) | 0 (0) | 0 (0) | <0.001 |
| ≥30 and <40 | 49 (2) | 1 (0) | 0 (0) | 48 (12) | 0 (0) | 0 (0) | |
| ≥40 and <50 | 179 (8) | 22 (4) | 0 (0) | 157 (40) | 0 (0) | 0 (0) | |
| ≥50 and <60 | 410 (19) | 148 (25) | 4 (11) | 158 (40) | 15 (7) | 85 (10) | |
| ≥60 and <70 | 710 (33) | 233 (40) | 17 (46) | 0 (0) | 59 (25) | 401 (45) | |
| ≥70 and <80 | 667 (31) | 167 (29) | 15 (41) | 0 (0) | 125 (54) | 360 (40) | |
| ≥80 | 96 (5) | 15 (3) | 1 (3) | 0 (0) | 33 (14) | 47 (5) | |
| Male sex | 1,523 (71) | 576 (98) | 37 (100) | 235 (60) | 131 (57) | 544 (61) | <0.001 |
| Smoking history | <0.001 | ||||||
| Current smoker | 687 (32) | 306 (52) | 8 (22) | 147 (37) | 42 (18) | 184 (21) | |
| Ex-smoker | 790 (37) | 280 (48) | 29 (78) | 85 (22) | 80 (35) | 316 (35) | |
| Never smoker | 663 (31) | 0 (0) | 0 (0) | 160 (41) | 110 (47) | 393 (44) | |
| Smoking pack-years | 20.3±22.5 | 45.3±12.2 | 102.9±14.7 | 9.4±10.7 | 6.9±9.6 | 8.6±10.0 | <0.001 |
Note: Data are presented as mean ± SD or number (%).
Abbreviations: COPD, chronic obstructive pulmonary disease; BMI, body mass index; SD, standard deviation; FEV1, forced expiratory volume in 1 second.