AIMS To examine the prevalence of asthma symptoms, bronchial hyperresponsiveness (BHR) and atopy in a random population sample of New Zealand adults. METHODS A random sample of 2004 adults, aged 20-44 years, in Hawkes Bay, Wellington and Christchurch, were selected from respondents to a one-page respiratory screening questionnaire and invited to take part in further testing. Subjects attending the testing centres' laboratories underwent a detailed respiratory symptom questionnaire, Phazet testing to eleven common allergens, blood samples for total and specific IgE, and measurement of bronchial hyperresponsiveness. Subjects who did not wish to participate were encouraged to complete the questionnaire by telephone. RESULTS A participation rate of 67% (1257 of 1877 eligibles) was achieved. We found a high prevalence for all measures of asthma in the previous 12 months: wheezing was reported by 28.5%, waking with shortness of breath by 7.7%, a physician diagnosis of asthma by 15.9% and asthma medications were used by 8.5%. Bronchial hyperresponsiveness was found in 24.9%, atopy in 34.8% and elevated serum IgE levels in 30.5%. Asthma symptoms (in the past 12 months) and atopy decreased with increasing age, whereas bronchial hyperresponsiveness increased with age. Females reported higher prevalences of waking with coughing (45.9%), nasal allergies (43.5%) and skin allergies (48.8%) compared to males (30.5%, 31.9% and 37.0%, respectively). There were no significant regional differences. CONCLUSIONS Asthma symptoms, bronchial hyperresponsiveness and atopy are all common in adult New Zealanders. Their prevalence is associated with age, gender and current smoking but there are no significant regional differences between Hawkes Bay, Wellington and Christchurch.

In recent years, airway responsiveness has commonly been measured in epidemiological studies using one of two methods. In one method, histamine is administered via a handheld DeVilbiss nebulizer and in the other, methacholine is administered via a dosimeter. Allergic sensitivity has commonly been measured by either the allergen droplet method or by Phazet. We wanted to assess the comparability of airway responsiveness and of allergic sensitivity measured by both methods. A total of 48 volunteers, including normal and asthmatic subjects, participated in the study. Subjects first underwent one of the two tests of airway responsiveness and allergic sensitivity, and then returned within 10 days to undergo tests using the second protocol. Commencement protocol was allocated in random order. There was good agreement between both methods for assessing airway responsiveness and for assessing allergic sensitivity. The difference for dose response ratio (DRR) between histamine and methacholine was a 1.19 (95% (CI) 0.78, 1.82) fold changes, which was not statistically significant. Agreement between allergic sensitivity methods was perfect for Alternaria tenuis, good for rye-grass (kappa = 0.71) and moderate for cat and Dermatophagoides pteronyssinus (kappa approximately 0.5). It is possible to compare data from epidemiological studies which use these methods.