Asthma exacerbation trajectories and their predictors in children with incident asthma.

BACKGROUND: Asthma exacerbation trajectories in children after incident asthma diagnosis are understudied. OBJECTIVE: To identify trajectories of asthma exacerbation and predictors of these trajectories in children with incident asthma. METHODS: Children from the National Longitudinal Survey of Children and Youth, Canada, with incident asthma were followed-up for up to 12 years during childhood. Latent class growth modeling was used to identify distinct asthma exacerbation trajectory groups. Multinomial logistic regression was performed to identify predictors of trajectory group membership. RESULTS: The mean age at asthma diagnosis among 403 children was 5.9 years. Three distinct trajectories were identified: low increasing (21.3% of children), medium decreasing (45.8% of children), and high decreasing (32.8% of children). Asthma attack probability increased gradually after diagnosis in low increasing group, decreased from moderate level after diagnosis to almost zero probability at the end of follow-up in the medium decreasing group, and decreased after diagnosis but remained higher in the high decreasing group than the other 2 groups at 12 years after diagnosis. Children having more siblings at home were more likely to belong to the medium decreasing and high decreasing trajectory groups, whereas children older at asthma diagnosis were less likely to belong to the medium decreasing and high decreasing trajectory groups than the low increasing trajectory group. CONCLUSION: Our results suggest that children with incident asthma follow 3 distinct trajectories of asthma exacerbations after asthma diagnosis. The trajectory group with initial moderate exacerbation probability has better long-term prognosis

Age, period, and cohort effects on asthma prevalence in Canadian adults, 1994-2011.

PURPOSE: To examine the age, period, and cohort effects on asthma prevalence among Canadian adults from 1994/1995 to 2010/2011. METHODS: Using data from the National Population Health Survey, 13,616 Canadian adults were followed for 16 years. Age was limited to 18-80 years during follow-up. Modified Poisson regression models with generalized estimating equations were used to estimate age, period, and cohort effects on asthma and active asthma prevalence after accounting for sociodemographic factors. Model-based standardization was performed to estimate standardized rates. RESULTS: Overall asthma prevalence increased from 5% in 1994/1995 to 11% in 2010/2011; decreasing from 12% for 20-year-olds to 6% for 50-60-year-olds and then increased to 8% for 80-year-olds. Individuals aged 20 years had the steepest increase in prevalence between 1994/1995 and 2010/2011. Active asthma prevalence increased from 5% in 1994/1995 to 8% in 2010/2011; decreasing from 8% for 20-year-olds to 5% for 50-60-year-olds and then increased to 6% for 80-year-olds. CONCLUSIONS: Our findings suggest the presence of age, period, and cohort effects on prevalence of asthma overall and presence of age and period effects on active asthma prevalence in Canadian adults