Table 1.
Defined outcomes in mid-childhood and association with physician diagnosed asthma at age 7 years
| Outcome | Definition | Age at assessment (yrs) | Physician diagnosed asthma at 7 years | P* | |
|---|---|---|---|---|---|
| No (N=4545) | Yes (N=1132) | ||||
| Atopic asthma | Physician diagnosed asthma and SPT positive** | 7-8 | 0/4545 (0.0) | 332/861 (38.6) | - |
| Non-atopic asthma | Physician diagnosed asthma and SPT negative** | 7-8 | 0/4545 (0.0) | 529/861 (61.4) | - |
| Asthma medication | Use of asthma medication in past 12 months** | 7-8 | 66/4520 (1.5) | 689/1120 (61.5) | <0.001 |
| Persistent wheeze | Wheeze phenotype 'persistent'† | 0-7 | 47/4466 (1.1) | 322/1112 (29.0) | <0.001 |
| Late onset wheeze | Wheeze phenotype 'late onset'† | 0-7 | 109/4466 (2.4) | 174/1112 (15.6) | <0.001 |
| Intermediate onset wheeze | Wheeze phenotype 'intermediate onset'† | 0-7 | 14/4466 (0.3) | 119/1112 (10.7) | <0.001 |
| Prolonged early wheeze | Wheeze phenotype 'prolonged early'† | 0-7 | 272/4466 (6.1) | 142/1112 (12.8) | <0.001 |
| Transient early wheeze | Wheeze phenotype 'transient early'† | 0-7 | 451/4466 (10.1) | 104/1112 (9.4) | 0.502 |
| SPT positive | At least 1 positive skin prick test‡ | 7-8 | 539/3484 (15.5) | 332/861 (38.6) | <0.001 |
| BHR | 3rd tertile of bronchial challenge dose-response slope§ | 8-9 | 560/2410 (23.2) | 241/524 (46.0) | <0.001 |
| Low FEV1 | FEV1 z-score <20th percentile of normal distribution | 8-9 | 593/3456 (17.2) | 199/873 (22.8) | <0.001 |
| Low FVC | FVC z-score <20th percentile of normal distribution | 8-9 | 625/3510 (17.8) | 152/882 (17.2) | 0.730 |
| High systolic BP | 5th quintile of systolic blood pressure | 7-8 | 705/3946 (17.9) | 196/984 (19.9) | 0.140 |
| High IQ | 5th quintile of IQ total score | 8-9 | 736/3680 (20.0) | 161/921 (17.5) | 0.085 |
| High body height | 5th quintile of body height | 7-8 | 727/3995 (18.2) | 146/997 (14.6) | 0.008 |
Prevalence among children with and without diagnosed asthma are reported as n/N(%). Abbreviations: SPT Skin prick test, BHR bronchial hyper-responsiveness, BP blood pressure, IQ intelligence quotient
*
P-value of Fisher’s exact test
†
Phenotypes of wheezing in the first 7yrs of life were defined using latent class analysis as reported previously3.
‡
Mean weal diameter ≥2mm to house dust mite, cat or grass pollen.
§
Tertiles were formed among children with a positive dose response slope. Children with a dose response slope ≤0 were then grouped together with children in the lowest tertile.
**
based on parental report