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.