The course of asthma: A population-based 10-year study examining asthma remission in children diagnosed with asthma in preschool.

Background: The natural course of asthma may differ depending on the age of onset.

Objective: To investigate predictors of asthma remission with a focus on the age of asthma onset.

Methods: The study was a retrospective birth cohort of children with asthma in Saskatchewan, Canada. Using the Saskatchewan Ministry of Health databases, we identified children with a diagnosis of asthma in the first 6 years of life and who had at least 10 years of follow-up after diagnosis (n = 22 563). Of these, we included 6393 children either with persistent asthma (≥1 physician visit or hospitalization for asthma [PVHA] during each year of follow-up) and those who had remission (had PVHA in the first year after diagnosis but at some point during the follow-up no longer received PVHA until end of the study). We used survival analysis to examine associations between remission and age of asthma onset.

Results: Of the study participants, 87.2% had early-onset (≤3 years) and 12.8% had late-onset (4-6 years) asthma. Over the 10-years of follow-up, the rate of asthma remission was 37 per 100 person-years. Early-onset asthma (hazard ratio [HR] = 1.10; 95%confidence interval [CI]: 1.01-1.20), being female (HR = 1.12; 95%CI: 1.07-1.18), living in a rural (HR = 1.20; 95%CI: 1.14-1.27) and medium urban (HR = 1.16; 95%CI: 1.08-1.26) location were positively associated with remission while history of atopy decreased likelihood of remission (HR = 0.73; 95%CI: 0.54-0.97).

Conclusion: Most children with asthma experienced remission, especially those with the onset of symptoms within the first 3 years of life.