RESPIRATORY QUESTIONNAIRE RESPONSES - HOW THEY CHANGE WITH TIME

Aim. Responses to respiratory questionnaires are often used to identif y individuals with asthma symptoms and may also be used to identify as ymptomatic individuals. This study investigates the repeat responses o ver four years to such a questionnaire in a population of adult New Ze alanders. Methods. Seven hundred and twenty three asthmatics were sent two almost identical questionnaires in three areas of New Zealand, se parated by approximately four years. All of them had answered yes to a t least one of the three questions under study in the first survey. Re sults. Following the second asthma questionnaire only 487 (67.4%) answ ered yes to at least one of the survey questions. Similarly, 51.1% of those who had reported having nocturnal shortness of breath in the fir st survey did so in the second survey, 69.9% of those who reported hav ing had an asthma attack in the first survey did so in the second surv ey, and finally 74.8% of those who reported using asthma medication in the first survey did so in the second survey.Conclusion. Even in a pr eviously identified symptomatic asthmatic group, a large proportion di d not report respiratory symptoms and asthma medication use four years later. This implies that the true prevalence pool of susceptibles is likely to be far greater than is identified in surveys of the 12-month period prevalence of asthma symptoms. This has implications not only for the design of epidemiological studies (eg, it poses problems for t he selection of a control group of non-asthmatics in prevalence case-c ontrol studies), but also for the planning of health services and educ ational programmes for people with asthma.