Table 1

Characteristics of study participants at the beginning of follow-up (n=338 548)

Baseline characteristicOverall (n=338 548)COPD*P value
No (n=326 169)Yes (n=12 379)
Sex<0.001
 Male146 996 (43.4)140 581 (43.1)6415 (51.8)
 Female191 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
 <60247 301 (73.1)243 538 (74.7)3763 (30.4)
 60–6960 595 (17.9)55 954 (17.2)4641 (37.5)
 ≥7030 652 (9.1)26 677 (8.2)3975 (32.1)
Income percentile<0.001
 ≤30th72 260 (21.3)68 991 (21.2)3269 (26.4)
 >30th–≤70th123 133 (36.4)118 860 (36.4)4273 (34.5)
 >70th143 155 (42.3)138 318 (42.4)4837 (39.1)
Residential area<0.001
 Metropolitan218 442 (64.5)212 255 (65.1)6187 (50.0)
 Rural120 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
 Underweight9286 (2.7)8569 (2.6)717 (5.8)
 Normal126 645 (37.4)122 082 (37.4)4563 (36.9)
 Overweight87 561 (25.9)84 678 (26.0)2883 (23.3)
 Obese115 056 (34.0)110 840 (34.0)4216 (34.1)
Smoking status<0.001
 Never241 633 (71.4)233 266 (71.5)8367 (67.6)
 Past21 818 (6.4)21 016 (6.4)802 (6.5)
 Current75 097 (22.2)71 887 (22.0)3210 (25.9)
Charlson comorbidity index0 (0–1)0 (0–1)1 (0–1)<0.001
 0231 106 (68.3)223 581 (68.5)7525 (60.8)
 172 788 (21.5)69 896 (21.4)2892 (23.4)
 ≥234 654 (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.