Summary of covariates and unadjusted estimated odds ratios for asthma and chronic airways disease cases and controls. Figures in parentheses are percentages. High values of the deprivation score indicate the most deprived areas (the Carstairs index has mean zero across England and Wales)
| Covariate | Asthma cases | Asthma controls | COAD cases | COAD controls |
| Sex | ||||
| Male | 23 (18.4) | 23 (18.4) | 75 (60.5) | 75 (60.5) |
| Female | 102 (81.6) | 102 (81.6) | 49 (39.5) | 49 (39.5) |
| Age (y) | ||||
| 15–40 | 73 (58.4) | 70 (56.0) | 2 (1.6) | 0 (0) |
| 41–65 | 41 (32.8) | 40 (32.0) | 45 (36.3) | 54 (43.5) |
| 66–90 | 11 (8.8) | 13 (10.4) | 77 (62.1) | 70 (56.5) |
| Ethnic group | ||||
| White | 65 (52.0) | 71 (56.8) | 85 (68.5) | 84 (67.7) |
| Asian | 28 (22.4) | 24 (19.2) | 19 (15.3) | 21 (16.9) |
| Black | 2 (1.6) | 6 (4.8) | 0 (0) | 0 (0) |
| Other | 25 (20.0) | 15 (12.0) | 13 (10.5) | 13 (10.5) |
| Unknown | 5 (4.0) | 9 (7.2) | 6 (4.8) | 6 (4.8) |
| Deprivation | ||||
| Median | 6.6 | 5.98 | 6.21 | 6.13 |
| (1st, 3rd quartiles) | (4.4,11.1) | (4.4,9.7) | (4.7,10.6) | (4.3,9.9) |
| Distance | ||||
| ⩽150 m | 84 | 91 | 85 | 87 |
| >150 m | 41 | 34 | 39 | 37 |
| Estimated odds ratio = 0.78 | Estimated odds ratio = 0.94 | |||
| (95% CI 0.46, 1.32) | (95% CI 0.57, 1.54) | |||