Longitudinal assessment of airway responsiveness from 1 month to 18 years in the PIAF birth cohort.

The Perth Infant Asthma Follow-up (PIAF) study involves a birth cohort of unselected subjects who have undergone longitudinal assessments of airway responsiveness at 1, 6 and 12 months and 6, 11 and 18 years of age. The aim of this study was to determine the relationship between increased airway responsiveness throughout childhood and asthma in early adult life.Airway responsiveness to histamine, assessed as a dose-response slope (DRS), and a respiratory questionnaire were completed at 1, 6 and 12 months and 6, 11 and 18 years of age.253 children were initially recruited and studied. Airway responsiveness was assessed in 203, 174, 147, 103, 176 and 137 children at the above-mentioned time points, respectively (39 participants being assessed on all test occasions). Asthma at 18 years was associated with increased airway responsiveness at 6, 12 and 18 years, but not during infancy (slope 0.24, 95% CI 0.06-0.42; p=0.01; slope 0.25, 95% CI 0.08-0.49; p=0.006; and slope 0.56, 95% CI 0.29-0.83; p<0.001, respectively).Increased airway responsiveness and its association with asthma at age 18 years is established between infancy and 6 years. We propose that airway responsiveness in early life reflects the initial airway geometry and airway responsiveness later in childhood increasingly reflects immunological responses to environmental influences.

A longitudinal study of lung function from 1†month to 18†years of age.

BACKGROUND: Our hypothesis was that factors associated with wheeze will be associated with changes in lung function trajectory between 1 month and 18 years of age. METHODS: Measurements of lung function were made in individuals aged 1, 6 and 12 months (V'maxFRC), and also at ages 6, 12 and 18 years (FEF(25-75)). Changes in lung function over time relative to sex, a history of asthma, maternal asthma and other factors were explored using random coefficient models. RESULTS: Lung function (maximal flow at functional residual capacity in infants and FEF(25-75) in children) was determined in 241 individuals at 1 month, 192 at 6 months, 164 at 12 months, 106 at 6 years, 183 at 12 years and 141 at 18 years. In the multivariable model, maternal asthma (mean reduction in lung function 9.8%), flow limitation (mean reduction 17.4%), infant atopy (mean reduction 12.6%) and maternal smoking (mean reduction in lung function 8.1%) were acting independently. When interactions with time were sought, the reduction in lung function associated with maternal asthma and infant atopy were consistent over time, but % lung function increased in boys by a mean of 1%/year compared with girls, in flow-limited individuals by 3.0%/year and by 0.9%/year for those exposed to maternal smoking during pregnancy compared to other cohort members. CONCLUSIONS: Decrements in lung function in 18-year-olds associated with maternal asthma and early onset atopy may be determined by 1 month of age. Low initial lung function in some individuals can 'recover' in some settings.