Association between asthma control trajectories in preschoolers and disease remission.

INTRODUCTION: Early disease morbidity has been associated with asthma persistence in wheezing preschoolers; however, whether asthma control trajectories shortly after diagnosis could influence remission is unknown. We examined the association between asthma control trajectories 2 years post-diagnosis in preschoolers and subsequent disease remission. METHODS: We conducted a multicentre population-based retrospective cohort study consisting of 48 687 children with asthma diagnosed before 5 years old and born between 1990 and 2013 in four Canadian provinces who had prolonged disease activity post-diagnosis. Prolonged disease activity was defined as one or more medical visits or medications for asthma every 6-month period for at least four of the six periods post-diagnosis. Follow-up began at 3 years post-diagnosis (at cohort entry). Remission was defined as 2 consecutive years without drug claims or medical visits for asthma or asthma-like conditions following cohort entry. Asthma control trajectories, ascertained over four 6-month periods following diagnosis using a validated index, were classified as: "controlled throughout", "improving control", "worsening control", "out of control throughout" and "fluctuating control". Adjusted Cox models estimated associations between asthma control trajectories and time to remission. A random effects meta-analysis summarised province-specific hazard ratios (HRs). RESULTS: The pooled remission rate was 8.91 (95% CI 8.80-9.02) per 100 person-years. Compared with children controlled throughout, poorer asthma control was associated with incrementally lower hazard ratios of remission in four other trajectories: improving control (HR 0.89, 95% CI 0.82-0.96), fluctuating control (HR 0.78, 95% CI 0.71-0.85), worsening control (HR 0.68, 95% CI 0.62-0.75) and out of control throughout (HR 0.52, 95% CI 0.45-0.59). CONCLUSIONS: Asthma control trajectories 2 years following a diagnosis in preschoolers were associated with remission, highlighting the clinical relevance of documenting control trajectories in early life.

Association Between Asthma Control Trajectories in Preschoolers and Long-Term Asthma Control.

BACKGROUND: The potential influence of asthma control in early life on long-term outcomes in childhood remains largely unknown. OBJECTIVE: To examine whether asthma control trajectories in the 2 years after diagnosis in preschoolers are associated with long-term unsatisfactory asthma control. METHODS: We conducted a multicenter population-based retrospective cohort study, including four Canadian provincial birth cohorts derived from administrative databases. We included preschoolers (aged <5 years) with a diagnosis of asthma, defined as having one hospitalization or two physician visits for asthma within 2 years. Asthma control trajectories, ascertained over four 6-month periods after diagnosis using a validated index, were classified as controlled throughout, improving control, fluctuating control, worsening control, and out of control throughout. Long-term unsatisfactory control was defined as four or more short-acting ß2-agonist average doses per week or an exacerbation, measured within 6 months before index ages 6, 8, 10, 12, 14, and 16 years. Average risk ratios for long-term unsatisfactory control across all index ages were estimated using a robust Poisson model by province and meta-analyzed with a random effects model. RESULTS: In 50,188 preschoolers with asthma, the pooled average risk of having unsatisfactory control at any index age was 42% (95% confidence interval, 34.6-49.4). Compared with children who were controlled throughout, incrementally higher average risk ratios (95% confidence interval) of long-term unsatisfactory control were observed in each trajectory: improving control, 1.38 (1.28-1.49); fluctuating control, 1.54 (1.40-1.68); worsening control, 1.70 (1.55-1.86) and out of control throughout, 2.00 (1.80-2.21). CONCLUSIONS: Suboptimal asthma control trajectories shortly after a preschool diagnosis were associated with long-term unsatisfactory asthma control. Early control trajectories appear to be promising for predicting the risk for long-term adverse outcomes.