Characteristics of study subjects and comparison with subjects from original sample who were not retraced
| Study subjects (n = 7609) | Subjects unable to trace (n = 1941) | p value | |
|---|---|---|---|
| *Skin tests only performed in subsample. | |||
| Sex | |||
| Males | 3594 (47.2%) | 897 (46.2%) | |
| females | 4015 (52.8%) | 1044 (53.8%) | 0.42 |
| Age | |||
| Median (interquartile range) | 18 (11–34) | 18 (11–34) | 0.39 |
| Social class based on ownership of goods | |||
| Car | 336 (4.4%) | 32 (1.6%) | |
| Television, no car | 605 (8.0%) | 190 (9.8%) | |
| Telephone, none of above | 759 (10.0%) | 188 (9.7%) | |
| Radio, none of above | 3412 (44.8%) | 821 (42.3%) | |
| None of above | 2497 (32.8%) | 710 (36.6%) | <0.001 |
| Smoking status | |||
| Ever smoked | 293 (3.9%) | 85 (4.4%) | |
| Never smoked | 7316 (96.1%) | 1856 (95.6%) | 0.29 |
| Wheezed in past year | |||
| Yes | 289 (3.8%) | 64 (3.3%) | |
| No | 7320 (96.2%) | 1877 (96.7%) | 0.30 |
| Sensitisation to dust mite* | |||
| Yes | 56 (3.3%) | 27 (4.6%) | |
| No | 1665 (96.7%) | 560 (95.4%) | 0.13 |
| Eczema symptoms ever | |||
| Yes | 103 (1.4%) | 29 (1.5%) | |
| No | 7506 (98.6%) | 1912 (98.5%) | 0.64 |
| Rhinitis symptoms ever | |||
| Yes | 232 (3.0%) | 66 (3.4%) | |
| No | 7377 (97.0%) | 1875 (96.6%) | 0.43 |