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A group of children with a past history of wheezing was randomly selected from the Melbourne community at the age of 7 years in 1964, and a further group of children with severe wheezing was selected from the same birth cohort at the age of 10 years. These subjects have been followed prospectively at 7-year intervals, with the last review in 1999, when their average age was 42 years. Eighty-seven percent of the original cohort who were still alive participated in the 1999 review. This study showed that the majority of children who had only a few episodes of wheezing associated with symptoms of a respiratory infection had a benign course, with many ceasing to wheeze by adult life. Most who continued with symptoms into adult life were little troubled by them. Conversely, those children with asthma mostly continued with significant wheezing into adult life, and the more troubled they were in childhood, the more likely symptoms continued. There was a loss in lung function by the age of 14 years in those with severe asthma, but the loss did not progress in adult life. The childhood asthma had been treated before the availability of inhaled steroids. There was no significant loss of lung function in those with milder symptoms.

The respiratory symptoms and respiratory function of 680 schoolchildren from two rural area of South Australia were studied. The initial results of this prospective, longitudinal study showed that the cumulative prevalence of asthma and/or wheezy breathing was 27.4% in the Burra population and 23.1% in the Kingston population. The cumulative prevalence of one or more attacks of asthma/wheezy breathing amongst Burra (38.8%) and Kingston (23%) children aged up to 8 years was significantly higher than that reported for urban Melbourne children (11%, p less than 0.01). The combined South Australian group reported a cumulative prevalence of asthma/wheezy breathing alone of 10% which was significantly higher than the cumulative prevalence rates in three previous studies reported in Australia (1.8%, 2.6%, 2.7%, p less than 0.01). The highest overall cumulative prevalence of bronchitis/loose or productive cough occurred in the 12 year old Burra children (41.5%). Burra girls had the highest prevalence of bronchitis/loose or productive cough (36.8%) compared to other groups studied at both locations. The parental smoking rate (60.4% in Burra, 57.4% in Kingston) is much higher than the national figure reported by the Bureau of Statistics in 1977 (35.9%). The prevalence of asthma/wheezy breathing is much higher in the South Australian cohort compared to the Queensland and Tasmanian cohorts studied using the same questionnaire. Predicted respiratory function parameters using initial algorithms are similar to those reported for urban Australian children.

Ninety six middle aged male patients with chronic bronchitis with relatively well preserved ventilatory function who were resident in Queensland, New South Wales, or Victoria took part in a prospective study to determine the relationship of various factors to the rate of decline of the FEV1. Thirty of the subjects withdrew, leaving 66 to be followed for four to six years. The mean rate of decline of the FEV1 was 58.6 (SD 51.4) ml/year. The subjects' ventilatory responses to bronchodilator and to methacholine (measures of bronchial lability) were significantly related to each other and to sputum eosinophilia. With a linear model for the data on 57 patients who had methacholine and skin tests the rate of decline of the FEV1 was found, after adjustment had been made for other variables, to be significantly related to State of residence, current smoking, response to bronchodilator, age, and occupational exposure to dust. Response to bronchodilator was interchangeable with response to methacholine. With the five variables in the model none of the following factors was related to the rate of decline of the FEV1:FEV1 on entry, FEV1% predicted normal, FEV1/VC%, skin test reaction, occupation on entry, history of sinusitis and rhinitis, and height. When data from all 66 subjects were introduced into the model, in addition to the five significant individual variables (FEV1/VC% X response to bronchodilator) was significantly related to the rate of decline of the FEV1. Of these prognostic indices, response to bronchodilator was independent of the initial FEV1, FEV/VC%, and FEV1% predicted. The difference between States, which was not explained by differences due to sampling or withdrawal of subjects, was due to a low rate of decline in Queensland.

A prospective study of respiratory illness history and lung function of 10,898 school children in Sydney was begun in 1971. At the first visit, a history of previous asthma and of bronchitis before and after the first 2 years of life was obtained from a parental questionnaire, and maximal expiratory flow-volume curves were recorded. These lung function studies were repeated yearly between 1972 and 1974, at which time a history of respiratory illness during the previous 12 months and a personal smoking history were recorded, Two groups of children from a random selection of primary and secondary schools in Sydney were studied. Their respective mean ages were 8.9 yr (primary group) and 12.6 yr (high school group) in 1971. Mean values for the maximal flow at 50 percent of the forced vital capacity were lower in children with a history of bronchitis and/or asthma than those in the control group. This was true in both age groups in both sexes. No differences were found in the 0.5-s forced expiratory volume or forced vital capacity. The differences in maximal flow at 50 per cent of the forced vital capacity were present again in 1974. In 1974, the data from smokers were compared with those from nonsmokers; small differences were found. The results suggest that bronchitis in infancy and childhood as well as asthma may affect lung function as children grow, that the abnormality may not be detected by the forced expiratory volume, that the abnormality persists, and that it is possible that the abnormality is further affected by smoking.