INCREASE IN THE SELF-REPORTED PREVALENCE OF ASTHMA AND HAY-FEVER IN ADULTS OVER THE LAST GENERATION - A MATCHED PARENT-OFFSPRING STUDY

The study compared current measures on a population-based cohort of ad ults with past measures on their parents to determine whether the prev alence of self-reported asthma and hay fever in adults increased betwe en 1968 and the early 1990s. In 1968, 8585 cohort members (99 per cent of eligible Tasmanian 7-year-old school children born in 1961), 16 27 3 (95 per cent) of their parents (mean age 35 years) and 20 937 siblin gs completed a questionnaire about asthma and hay fever. In 1991-1993, 1494 members (75 per cent) of a stratified random sample of the cohor t (aged 29 to 32 years), 75 per cent resident in Tasmania, were survey ed again. In 1968, the proportion of parents who reported having ever had asthma or attacks of wheezing like asthma was 10.9 per cent, indep endent of age and sex. In 1991-1993, the estimated adult prevalence of having ever suffered from attacks of asthma or wheezy breathing was 2 3.2 per cent. The proportion reporting at least one asthma attack with in the previous 10 years, 5 years, 2 years, 12 months and 6 months was 17.6 per cent, 16.1 per cent, 14.5 per cent, 13.3 per cent and 10.3 p er cent, respectively. For hay fever, the adult prevalence was 19.2 pe r cent in 1968, and 41.3 per cent in 1991-1993. The self-reported life time prevalence of asthma and hay fever among adults in the 1961 birth cohort of Tasmanians was twice as high in 1991-1993 as in their paren ts 25 years earlier. The change in disease interpretation necessary to account fully for the change in prevalence provides evidence for a re al increase. Nevertheless, unavoidable subtle differences in questioni ng could account for half the observed change in prevalence.