Persistence and remission in childhood asthma: a population-based asthma birth cohort study.

Objectives: To examine and predict the persistence of childhood asthma.

Design: Longitudinal population-based cohort study.

Setting: Ontario, Canada.

Participants: Children born in 1994 and diagnosed with asthma before age 6 years were followed up until age 11 years. Diagnosis of asthma was defined as 1 asthma hospitalization or 2 asthma physician claims within 3 years prior to age 6 years.

Main Exposure: Intensity of health services use within 1 year postdiagnosis.

Main Outcome Measures: Those who continued to have asthma events (hospitalization and/or physician visit) between ages 6 and 11 years were considered to have "persistent asthma," while others were in "remission." Cumulative rates of health services use for asthma during follow-up were calculated. Logistic regression analysis was used to estimate risks of persistent asthma.

Results: The study included 34,216 children diagnosed with asthma before age 6 years. More than half (54.4%) experienced a second asthma health care encounter within 1 year after diagnosis. By age 12 years, nearly half (48.6%) were in remission. Children with asthma hospitalization during the first year postdiagnosis had a 3-fold risk of persistent asthma by age 12 years (95% confidence interval, 2.69-3.39; P < .001). Those with at least 4 physician visits also had a 2.6-fold risk of persistent asthma during follow-up (95% confidence interval, 2.34-2.81; P < .001).

Conclusion: The concentration of health services use within 1 year following the initial diagnosis of childhood asthma points to the need for attentive follow-up and ongoing management and education strategies in the early years.