Characteristics (%) of cases and controls
| Patient characteristics | Cases (n=533) | Controls (n=533) | Odds ratio | 95% CI |
|---|---|---|---|---|
| *p<0.05, **p<0.01, ***p<0.001. | ||||
| †COPD defined as mention of chronic obstructive pulmonary disease, chronic obstructive airway disease, chronic bronchitis, or emphysema. | ||||
| ‡Significance test for trend based on fitting age as a continuous variable. | ||||
| §Includes 1.5% with age of onset mentioned only as “in childhood”; these were assigned average value for the <15 years category for purposes of significance testing. | ||||
| Odds ratios (from conditional logistic regression) and p values calculated ignoring the missing and unknown categories. Odds ratios are adjusted for sex. | ||||
| Age asthma first mentioned (years)‡** | ||||
| <15§ | 31.0 | 26.6 | 1.83 | (1.10 to 3.07) |
| 15–34 | 21.4 | 22.1 | 1.38 | (0.86 to 2.21) |
| 35–44 | 14.3 | 15.2 | 1.28 | (0.78 to 2.10) |
| 45–54 | 16.5 | 18.6 | 1.15 | (0.72 to 1.84) |
| 55–64 | 9.6 | 11.8 | 1.00 | – |
| Missing | 7.3 | 5.6 | – | – |
| Family history of asthma | 25.1 | 24.2 | 1.07 | (0.81 to 1.42) |
| Clinical evidence of atopy | 39.4 | 41.3 | 0.93 | (0.72 to 1.20) |
| Ever smoked | 58.3 | 59.3 | 0.94 | (0.73 to 1.21) |
| Co-morbidity mentioned ever | ||||
| Major non-respiratory illness | 44.1 | 43.0 | 1.05 | (0.81 to 1.35) |
| COPD† | 42.4 | 34.7 | 1.45** | (1.10 to 1.90) |
| Obesity | 30.6 | 25.0 | 1.37* | (1.04 to 1.81) |