Association of delayed asthma diagnosis with asthma exacerbations in children

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. To study the association of delayed diagnosis of asthma with asthma exacerbations (AE) in children. Using the Mayo Clinic birth cohort, we identified children with a diagnosis of asthma from electronic health records (EHRs). We defined onset date as the date when subjects first met Predetermined Asthma Criteria ascertained by an EHR-based natural language processing algorithm. Delay in diagnosis (DD) was defined as first diagnosis more than 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. 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 at least one AE during median follow-up period of 9.3 years. Children in DD group had a significantly increased risk of AE compared to TD (adjusted HR [95% CI]: 1.53 [1.28, 1.80], p