Table 1.
Characteristics of study participants at the beginning of follow-up (n=338 548)
| Baseline characteristic | Overall (n=338 548) | COPD* | P value | |
| No (n=326 169) | Yes (n=12 379) | |||
| Sex | <0.001 | |||
| Male | 146 996 (43.4) | 140 581 (43.1) | 6415 (51.8) | |
| Female | 191 552 (56.6) | 184 588 (56.9) | 5964 (48.2) | |
| Age (years) | 52.9 (10.5) | 52.5 (10.3) | 62.0 (9.6) | <0.001 |
| <60 | 247 301 (73.1) | 243 538 (74.7) | 3763 (30.4) | |
| 60–69 | 60 595 (17.9) | 55 954 (17.2) | 4641 (37.5) | |
| ≥70 | 30 652 (9.1) | 26 677 (8.2) | 3975 (32.1) | |
| Income percentile | <0.001 | |||
| ≤30th | 72 260 (21.3) | 68 991 (21.2) | 3269 (26.4) | |
| >30th–≤70th | 123 133 (36.4) | 118 860 (36.4) | 4273 (34.5) | |
| >70th | 143 155 (42.3) | 138 318 (42.4) | 4837 (39.1) | |
| Residential area | <0.001 | |||
| Metropolitan | 218 442 (64.5) | 212 255 (65.1) | 6187 (50.0) | |
| Rural | 120 106 (35.5) | 113 914 (34.9) | 6192 (50.0) | |
| Body mass index (kg/m2) | 23.92 (3.13) | 23.93 (3.12) | 23.78 (3.39) | <0.001 |
| Underweight | 9286 (2.7) | 8569 (2.6) | 717 (5.8) | |
| Normal | 126 645 (37.4) | 122 082 (37.4) | 4563 (36.9) | |
| Overweight | 87 561 (25.9) | 84 678 (26.0) | 2883 (23.3) | |
| Obese | 115 056 (34.0) | 110 840 (34.0) | 4216 (34.1) | |
| Smoking status | <0.001 | |||
| Never | 241 633 (71.4) | 233 266 (71.5) | 8367 (67.6) | |
| Past | 21 818 (6.4) | 21 016 (6.4) | 802 (6.5) | |
| Current | 75 097 (22.2) | 71 887 (22.0) | 3210 (25.9) | |
| Charlson comorbidity index | 0 (0–1) | 0 (0–1) | 1 (0–1) | <0.001 |
| 0 | 231 106 (68.3) | 223 581 (68.5) | 7525 (60.8) | |
| 1 | 72 788 (21.5) | 69 896 (21.4) | 2892 (23.4) | |
| ≥2 | 34 654 (10.2) | 32 692 (10.0) | 1962 (15.9) | |
Values in the table are mean (SD), median (IQR) or n (%).
We used χ2 tests, t-tests, or rank-sum tests for comparing patients with and without COPD for categorical and continuous variables, as appropriate.
*COPD patients include those with COPD at baseline and those who developed COPD over follow-up.
COPD, chronic obstructive pulmonary disease.