Trends in the age of diagnosis of childhood asthma Dhenuka Kannan Radhakrishnan, MD, MSc, Sharon D. Dell, MD, MSc, Astrid Guttmann, MDCM, MSc, Salimah Z. Shariff, PhD, Kuan Liu, MSc, Teresa To, PhD  Journal of Allergy and Clinical Immunology  Volume 134, Issue 5, Pages 1057-1062.e5 (November 2014) DOI: 10.1016/j.jaci.2014.05.012 Copyright © 2014 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig 1 Study sample after meeting inclusion and exclusion criteria. All children born in Ontario from 1993 to 2000 were identified from the Discharge Abstract Database of the Canadian Institute for Health Information. This database was linked with the Ontario Registered Persons Database to identify and exclude those children who had died at age less than 6 months. Children with a missing Date of Last Contact (DOLC) from Ontario administrative databases were excluded on the assumption that these represented non-Ontario residents or people with invalid health card numbers. An additional 12 were removed because of negative date of birth (poor data quality). Records were further linked with the Ontario Health Insurance Plan (OHIP) database, and children with asthma were identified using the following administrative algorithm: 1 hospitalization for asthma (ICD-9 code 493 or ICD-10 codes J45 and J46) or 2 outpatient visits for asthma within 2 years. Children with an incident date of asthma at age less than 6 months were removed from the asthma cohort, unless they had a subsequent hospitalization or outpatient visit for “asthma” after age 12 months. All linkage was performed using the child's unique OHIP number. ICD-9, International Classification of Diseases, Ninth Revision; ICD-10, International Statistical Classification of Diseases, 10th Revision. Journal of Allergy and Clinical Immunology 2014 134, 1057-1062.e5DOI: (10.1016/j.jaci.2014.05.012) Copyright © 2014 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig 2 A, Incidence of asthma in the first 8 years of life per cohort, stratified by age at diagnosis. Total sample size: N = 1,059,511 children in total and 201,958 children with asthma. aP < .0001 for significant increase in overall asthma incidence and asthma incidence in children younger than 3 years by Cochrane Armitage trend test. B, Proportion of children with asthma hospitalized at diagnosis, stratified by age at diagnosis. Total sample size: N = 201,958 children with asthma. aP < .001 for significant increase over time in proportion of children younger than 3 years hospitalized at first asthma diagnosis. bP < .001 for significant reduction over time in proportion of children 3 years or older hospitalized at first asthma diagnosis. Journal of Allergy and Clinical Immunology 2014 134, 1057-1062.e5DOI: (10.1016/j.jaci.2014.05.012) Copyright © 2014 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig 3 A, Comparison of time to asthma diagnosis from birth across birth cohort groups. B, Comparison of time to hospitalization across birth cohorts for children hospitalized at first asthma diagnosis. Journal of Allergy and Clinical Immunology 2014 134, 1057-1062.e5DOI: (10.1016/j.jaci.2014.05.012) Copyright © 2014 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig 4 A, Non-asthma respiratory health care visits in the first 8 years of life among children without asthma by birth year. aP < .001 for significant decrease over time in proportion of children with hospitalization for nonasthma respiratory illness. bP < .001 for significant increase over time in proportion of children with outpatient non-asthma respiratory visits. B, Non-asthma respiratory health care visits among children younger than 3 years without asthma. aP < .001 for significant decrease over time in proportion of children younger than 3 years without asthma with a nonasthma respiratory health care visit by Cochrane Armitage trend test. bP < .001 for significant decrease in proportion of children younger than 3 years with hospitalization for non-asthma respiratory illness. cP < .001 for significant increase over time in proportion of children younger than 3 years with outpatient visit for non-asthma respiratory illness. Journal of Allergy and Clinical Immunology 2014 134, 1057-1062.e5DOI: (10.1016/j.jaci.2014.05.012) Copyright © 2014 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig E1 Comparison of time to first non-asthma respiratory hospitalization by birth cohort groups. Journal of Allergy and Clinical Immunology 2014 134, 1057-1062.e5DOI: (10.1016/j.jaci.2014.05.012) Copyright © 2014 American Academy of Allergy, Asthma & Immunology Terms and Conditions