| Non-wheeze | Undiagnosed wheeze | Asthma | |
| Demographics | |||
| Female sex | 49 (493/1008) | 59 (38/64) | 55 (128/234) |
| p-value | Ref. | 0.3 | 0.33 |
| Low social class# | 32 (292/909) | 42 (22/53) | 35 (74/212) |
| p-value | Ref. | 0.48 | 1 |
| Family history of asthma¶ | 43 (419/966) | 61 (36/59) | 62 (139/226) |
| p-value | Ref. | 0.02 | <0.001 |
| Still in education at age 18 yrs | 71 (699/990) | 59 (36/61) | 70 (161/230) |
| p-value | Ref. | 0.18 | 1 |
| In work at age 18 yrs | 68 (675/991) | 66 (40/61) | 69 (158/230) |
| p-value | Ref. | 1 | 1 |
| Atopy, FeNO and self-rated health status | |||
| Atopy at 18 yrs | 34 (221/643) | 38 (17/45) | 69 (114/165) |
| p-value | Ref. | 1 | <0.001 |
| Atopy at 10 yrs | 20 (145/731) | 23 (11/47) | 57 (104/184) |
| p-value | Ref | 1 | <0.001 |
| Atopy at 4 yrs | 14 (99/703) | 25 (10/40) | 43 (68/159) |
| p-value | Ref. | 0.18 | <0.001 |
| FeNO ppb+ at 18 yrs | 17 (425) | 18 (24) | 31 (107) |
| p-value | Ref. | 1 | <0.001 |
| Self-rated health status VAS§ | 81 (932) | 72 (60) | 75 (216) |
| p-value | Ref. | <0.001 | <0.001 |
Data are presented as % (n/N) unless otherwise stated. Comparison of wheeze groups by Chi-squared test for categorical variables determined at p<0.05, group-wise significance adjusted for multiple comparisons. FeNO: exhaled nitric oxide fraction; VAS: visual analogue score. #: low social class categories (IIIM–V); ¶: parent or sibling history of asthma recorded at birth; +: geometric mean (n); §: low scores infer lower self-rated health status (n in parentheses).