Comparative outcomes of leukotriene receptor antagonists and long-acting β-agonists as add-on therapy in asthmatic patients: A population-based study  Mohsen Sadatsafavi, MD, PhD, Larry Lynd, PhD, Carlo Marra, PharmD, PhD, Pierrick Bedouch, PharmD, PhD, Mark FitzGerald, MD  Journal of Allergy and Clinical Immunology  Volume 132, Issue 1, Pages 63-69 (July 2013) DOI: 10.1016/j.jaci.2013.02.007 Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions

Fig 1 Schematic illustration of the cohort construction and analysis type. Horizontal lines with nodes at the end represent a dispensed medication. The left node is the dispensation date, and the length of each line represents the intended days of supply of the medication. The index date defines the first time the patient is considered exposed to ICS+LABA or ICS+LTRA. This date is the date of the second of 2 dispensations, one for ICS and another for the non-ICS component of the study medication, if such dispensations occur within 90 days of each other. Follow-up is fixed at 2 years for the ITT-based analysis. For the uninterrupted treatment analysis, it ends 30 days after the patient does not renew his or her dispensations within 30 days of the end of the supply of a previous dispensation. Journal of Allergy and Clinical Immunology 2013 132, 63-69DOI: (10.1016/j.jaci.2013.02.007) Copyright © 2013 American Academy of Allergy, Asthma & Immunology Terms and Conditions