Demographical characteristics and smoking status of 2,061 subjects by airway disease diagnosis
| COPD n (%) | Asthma alone n (%) | No chronic airway disease n (%) | p‐value | |
| Subjects n | 377 | 129 | 1555 | |
| Age yrs | ||||
| 55–59 | 106 (28) | 45 (35) | 457 (29) | 0.6 |
| 60–64 | 99 (26) | 32 (25) | 376 (24) | |
| 65–75 | 172 (46) | 52 (40) | 722 (47) | |
| Female sex | 237 (63) | 88 (68) | 847 (54) | <0.001 |
| Race/ethnicity | ||||
| White non-Hispanic | 326 (86) | 110 (85) | 1314 (85) | 0.03 |
| Hispanic | 15 (4) | 9 (7) | 117 (5) | |
| Black | 29 (8) | 4 (3) | 78 (8) | |
| Other | 7 (2) | 6 (5) | 46 (3) | |
| Education | ||||
| High school or less | 204 (54) | 47 (36) | 633 (41) | <0.001 |
| Some college | 101 (27) | 39 (30) | 486 (31) | |
| College degree or more | 72 (19) | 43 (33) | 436 (28) | |
| Household income* US$·yr−1 | ||||
| Subjects n | 325 | 113 | 1370 | |
| <20000 | 142 (44) | 31 (27) | 316 (23) | <0.001 |
| 20000–40000 | 104 (32) | 35 (31) | 431 (32) | |
| 40000–80000 | 53 (16) | 25 (22) | 425 (31) | |
| ≥80000 | 26 (8) | 22 (20) | 198 (14) | |
| Cigarette smoking status | ||||
| Never | 73 (19) | 59 (46) | 682 (44) | <0.001 |
| Former | 183 (49) | 55 (43) | 615 (40) | |
| Current | 121 (32) | 15 (12) | 258 (17) |
COPD: chronic obstructive pulmonary disease
*: proportion of missing values (n=253) did not differ by health condition category (p=0.6)