Asthma often starts before six years of age. However, there remains uncertainty as to when and how a preschool-age child with symptoms suggestive of asthma can be diagnosed with this condition. This delays treatment and contributes to both short- and long-term morbidity. Members of the Canadian Thoracic Society Asthma Clinical Assembly partnered with the Canadian Paediatric Society to develop a joint working group with the mandate to develop a position paper on the diagnosis and management of asthma in preschoolers. In the absence of lung function tests, the diagnosis of asthma should be considered in children one to five years of age with frequent (≥ 8 days/month) asthma-like symptoms or recurrent (≥ 2) exacerbations (episodes with asthma-like signs). The diagnosis requires the objective document of signs or convincing parent-reported symptoms of airflow obstruction (improvement in these signs or symptoms with asthma therapy), and no clinical suspicion of an alternative diagnosis. The characteristic feature of airflow obstruction is wheezing, commonly accompanied by difficulty breathing and cough. Reversibility with asthma medications is defined as direct observation of improvement with short-acting ß2-agonists (SABA) (with or without oral corticosteroids) by a trained health care practitioner during an acute exacerbation (preferred method). However, in children with no wheezing (or other signs of airflow obstruction) on presentation, reversibility may be determined by convincing parental report of a symptomatic response to a three-month therapeutic trial of a medium dose of inhaled corticosteroids with as-needed SABA (alternative method), or as-needed SABA alone (weaker alternative method). The authors provide key messages regarding in whom to consider the diagnosis, terms to be abandoned, when to refer to an asthma specialist and the initial management strategy. Finally, dissemination plans and priority areas for research are identified.

RATIONALE: While severe asthma affects approximately 5% of all individuals with asthma, this small minority of individuals accounts for a large proportion of the asthma-related costs. Greater understanding of the pathophysiology of asthma combined with the emergence of novel biologic therapies for severe asthma supported the need for a thorough review of the diagnosis, investigation, phenotyping, and management of severe asthma. OBJECTIVES: We aimed to propose a practical approach to distinguish uncontrolled asthma due to inadequate asthma management from severe asthma despite optimal asthma management. Moreover, based on emerging scientific evidence, we sought to provide guidance for characterizing individuals with severe asthma and considering a phenotype-specific management. We also aimed to review other novel new potential therapeutic approaches. METHODS: We systematically reviewed the relevant literature focusing on randomized controlled trials and when available, systematic reviews of randomized controlled trials. The proposed key messages, based on scientific evidence and expert opinion, were agreed upon by unanimous consensus. MAIN RESULTS: We defined severe asthma and outlined its significant impact from the societal and patient perspectives. We outlined a practical approach to distinguish severe from uncontrolled but not severe asthma, based on stepwise investigation and management of potential reasons for uncontrolled asthma. After reviewing the current evidence we concluded that: 1) Several biomarkers (e.g. sputum or blood eosinophil count, total IgE, or FeNO) can help identify potential responders to new therapeutic options; 2) Tiotropium may be considered as an add-on therapy for individuals 12 years of age and over with severe asthma uncontrolled despite combination ICS/LABA therapy; 3) The chronic use of macrolides may decrease asthma exacerbations in individuals 18 years of age and over with severe asthma independent of their inflammatory profile; 4) Children aged 6 years and older and adults who are sensitized to at least one relevant perennial allergen and who remain poorly controlled asthmatics despite high dose ICS and a second controller can benefit from the addition of anti-IgE therapy to reduce asthma exacerbations; due to the known risk of side effects associated with high-dose ICS in children, omalizumab should also be considered in children and adolescents who repeatedly exacerbate or have poor control when therapy is stepped down from high-dose to moderate-dose ICS and at least one other controller; 5) Anti-IL5 therapies may be considered for adults 18 years of age and over with severe eosinophilic asthma who experience recurrent asthma exacerbations in spite of high doses of ICS in addition to at least one other controller; and 6) Although bronchial thermoplasty has shown a decrease in asthma exacerbations in one study, its role in the treatment of severe asthma remains uncertain. CONCLUSIONS: After reviewing existing and emerging therapies for severe asthma, we developed ke...

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