Association of delayed asthma diagnosis with asthma exacerbations in children.

Background: There is a significant delay between symptom onset and diagnosis of childhood asthma, but the impact of this delay on asthma outcomes has not been well understood. Objectives: We sought to study the association of delayed diagnosis of asthma with asthma exacerbations (AEs) in children. Methods: Using the Mayo Clinic birth cohort, we identified children with a diagnosis of asthma from electronic health records. We defined onset date as the date when subjects first met predetermined asthma criteria ascertained by an electronic health records-based natural language processing algorithm. Delay in diagnosis (DD) was defined as first diagnosis >30 days from onset date (vs timely diagnosis [TD] within 30 days). The primary outcome was AE after the index date (for DD: first diagnosis date vs for TD: clinic visit at similar delay from diagnosis as matched DD counterpart). A Cox proportional hazard model was used to test the association between delayed diagnosis status and risk of AE, adjusting for sociodemographics, care quality, and asthma severity. Results: Among 537 matched pairs of DD and TD (median age at index date: 4.1 years), a total of 344 and 253 children in DD and TD, respectively, had ≥1 AE during median follow-up period of 9.3 years. Children in the DD group had a significantly increased risk of AE compared to TD (adjusted hazard ratio: 1.53; 95% CI: 1.28, 1.80; Conclusions: DD of asthma in children is associated with an increased risk of AE compared to TD. TD of asthma should be an important priority in childhood asthma management.