Table 2. Covariates according to COPD diagnosis at any time.
| % (n) | % (n) | P-value | |
| Characteristics | No diagnosis of COPD (n = 11493) | Diagnosis of COPD (n = 548) | Chi-square test |
| Study | |||
| Monica10 | 90.2 (2390) | 9.8 (259) | <0.0001 |
| Inter99 | 96.6 (5935) | 3.4 (211) | |
| Health2006 | 97.6 (3168) | 2.4 (78) | |
| Gender | |||
| Male | 95.4 (5536) | 4.6 (269) | 0.674 |
| Female | 95.5 (5957) | 4.5 (279) | |
| Age, years | |||
| ≤45 | 98.4 (4674) | 1.6 (76) | <0.0001 |
| 45–55 | 95.7 (3753) | 4.3 (168) | |
| ≥55 | 91.0 (3049) | 9.0 (303) | |
| Season of blood collection | |||
| Mar-May | 95.9 (2889) | 4.1 (123) | 0.190 |
| Jun-Aug | 94.8 (2573) | 5.2 (141) | |
| Sep-Nov | 95.3 (3574) | 4.7 (175) | |
| Dec-Feb | 95.8 (2457) | 4.2 (109) | |
| Education | |||
| No | 91.5 (1862) | 8.5 (172) | <0.0001 |
| Yes | 96.3 (9403) | 3.7 (358) | |
| Body mass index, kg/m2 | |||
| <18.5 | 87.2 (129) | 12.8 (19) | <0.0001 |
| 18.5–24.9 | 95.5 (5091) | 4.5 (241) | |
| 25–29.9 | 96.0 (4388) | 4.0 (185) | |
| ≥30 | 94.9 (1880) | 5.1 (102) | |
| Physical activity | |||
| Sedentary | 93.1 (2217) | 6.9 (165) | <0.0001 |
| Light | 95.9 (6908) | 4.1 (292) | |
| Moderate/vigorous | 97.2 (2203) | 2.8 (63) | |
| Weekly intake of fish | |||
| <twice | 94.6 (5894) | 5.4 (340) | <0.0001 |
| ≥twice | 96.9 (5382) | 3.1 (175) | |
| Smoking habits, g/day | |||
| Never smoker | 99.2 (4154) | 0.8 (33) | <0.0001 |
| Former smoker | 96.6 (3223) | 3.4 (115) | |
| Occasional smoker | 98.2 (335) | 1.8 (6) | |
| Current smoker, <15 | 92.8 (1321) | 7.2 (103) | |
| Current smoker, <25 | 90.0 (1796) | 10.0 (199) | |
| Current smoker, ≥25 | 87.4 (589) | 12.6 (85) | |
| Alcohol, drinks/week | |||
| 0 | 93.5 (1025) | 6.5 (71) | <0.0001 |
| ≤7 | 96.3 (4995) | 3.7 (189) | |
| ≤14 | 96.3 (2441) | 3.7 (94) | |
| >14 | 94.2 (2542) | 5.8 (157) | |
| FEV1% predicted | |||
| <60% | 42.9 (100) | 57.1 (133) | <0.0001 |
| 60–80% | 82.0 (845) | 18.0 (186) | |
| >80% | 98.0 (10101) | 2.0 (210) |
Abbreviations: COPD, chronic obstructive pulmonary disease; FEV1% predicted, forced expiratory volume in one second in % of predicted.