Table 1

Characteristics (%) of cases and controls

Patient characteristicsCases (n=533)Controls (n=533)Odds ratio95% 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§ (1.10 to 3.07)
    15–3421.422.11.38 (0.86 to 2.21)
    35–4414.315.21.28 (0.78 to 2.10)
    45–5416.518.61.15 (0.72 to 1.84)
Family history of asthma25.124.21.07 (0.81 to 1.42)
Clinical evidence of atopy39.441.30.93 (0.72 to 1.20)
Ever smoked58.359.30.94 (0.73 to 1.21)
Co-morbidity mentioned ever
    Major non-respiratory illness44.143.01.05 (0.81 to 1.35)
    COPD†42.434.71.45** (1.10 to 1.90)
    Obesity30.625.01.37* (1.04 to 1.81)