| Total (n = 314) | Not sensitised (n = 265) | Sensitised (n = 49) | OR (95% CI) | |
| Age mean (SD) years | 19.5 (9.4) | 19.6 (3.1) | 19.1 (2.7) | 1.0 (0.9 to 1.1) |
| Male gender | 43 (13.7) | 43 (16.2) | 0 (0.0) | – |
| Smoker | 38 (12.1) | 31 (11.7) | 7 (14.3) | 1.3 (0.5 to 3.0) |
| Symptoms indicative of asthma* | 139 (44.3) | 106 (40.0) | 33 (67.3) | 3.1 (1.6 to 5.9) ** |
| Symptoms indicative of COPD† | 30 (9.6) | 25 (9.4) | 5 (10.2) | 1.1 (0.4 to 3.0) |
| Allergic symptoms‡ | 140 (44.6) | 102 (38.5) | 38 (77.6) | 5.5 (2.7 to 11.3) ** |
| Skin symptoms¶ | 60 (19.1) | 48 (18.1) | 12 (24.5) | 1.5 (0.7 to 3.1) ** |
| Respiratory symptoms at work§ | 35 (11.1) | 22 (8.3) | 13 (26.5) | 4.0 (1.9 to 8.6) ** |
| Positive SPT to common allergens†† | 119 (37.9) | 85 (32.1) | 34 (69.4) | 4.8 (2.5 to 9.3) ** |
| Measurable PC20 (⩽32 mg/ml) | 106 (33.8) | 74 (27.9) | 32 (65.3) | 4.9 (2.5 to 9.3) ** |
Data presented as n (%) unless otherwise stated.
*Present if experienced at least one of the following: wheezing or whistling in the last 12 months; had an attack of shortness of breath in the last 12 months; asthma confirmed by physician; and/or start to cough induced by exercise, strenuous work, cold air, heavy smell, smoke or dust.
†Present if experienced at least one of the following: sometimes wake with a feeling of tightness in your chest first thing in the morning; awaken by cough at night in the last few months; bring up phlegm from chest first thing in the morning for at least 3 months each year; and/or had chronic bronchitis confirmed by doctor.
‡Present if experienced at least one of the following: develop eye or nasal or respiratory or skin symptoms when exposed to common allergen such as dust mite, animal hair or pollen; have an itchy runny nose or sneezing even when do not have a cold; and/or ever had “hay fever”.
¶Present if experienced urticaria and/or eczema
§Present if experienced at least one of the following symptoms at work: get itchy, red and/or watery eyes; get runny or stuffy nose or sneezing; get itchy, redness or rash on your skin; feel shortness of breath; start to cough; and/or start to wheeze.
††Defined as two positive skin reactions to a set of 11 common inhalants.
**Univariable p value<0.50.
95% CI, 95% confidence interval; COPD, chronic obstructive pulmonary diseases; OR, odds ratio; PC20; level of the methacholine concentration that caused a decrease in FEV1 of 20%; SPT, skin-prick test.