About 11% of trials have a moderate or severe ADR. All paediatric clinical trials should have a SMC.

Background: Acute severe childhood asthma is an infrequent, but potentially life-threatening emergency condition. There is a wide range of different approaches to this condition, with very little supporting evidence, leading to significant variation in practice. To improve knowledge in this area, there must first be consensus on how to conduct clinical trials, so that valid comparisons can be made between future studies. We have formed an international working group comprising paediatricians and emergency physicians from North America, Europe, Asia, the Middle East, Africa, South America, Central America, Australasia and the United Kingdom. Methods/design: A 5-stage approach will be used: (1) a comprehensive list of outcomes relevant to stakeholders will be compiled through systematic reviews and qualitative interviews with patients, families, and clinicians; (2) Delphi methodology will be applied to reduce the comprehensive list to a core outcome set; (3) we will review current clinical practice guidelines, existing clinical trials, and literature on bedside assessment of asthma severity. We will then identify practice differences in tne clinical assessment of asthma severity, and determine whether further prospective work is needed to achieve agreement on inclusion criteria for clinical trials in acute paediatric asthma in the emergency department (ED) setting; (4) a retrospective chart review in Australia and New Zealand will identify the incidence of serious clinical complications such as intubation, ICU admission, and death in children hospitalized with acute severe asthma. Understanding the incidence of such outcomes will allow us to understand how common (and therefore how feasible) particular outcomes are in asthma in the ED setting; and finally (5) a meeting of the Pediatric Emergency Research Networks (PERN) asthma working group will be held, with invitation of other clinicians interested in acute asthma research, and patients/families. The group will be asked to achieve consensus on a core set of outcomes and to make recommendations for the conduct of clinical trials in acute (Continued on next page)

ObjectiveTo determine the variability of primary and secondary outcomes used in trials of intravenous bronchodilators in children with acute severe paediatric asthma.MethodsSystematic search of MEDLINE, EMBASE, Cochrane CENTRAL and the WHO International Clinical Trials Registry Platform for randomised trials in children (less than18 years) with acute severe paediatric asthma comparing intravenous bronchodilator therapy to another treatment. Initial search was performed on 7 January 2016 with an updated search performed on 6 September 2018. Primary and secondary outcomes were collated.ResultsWe identified 35 published papers and four registered study protocols. 56 primary outcomes were found, the most common being a clinical asthma score (23/56; 41%). Other identified primary outcomes included bedside tests of respiratory function (11/56; 20%) and measures of length of stay (9/56; 16%). There were a total of 60 different secondary outcomes, the most common were various length of stay measures (24/60; 40%) and adverse events (11/60; 18%).ConclusionStudies comparing intravenous treatment modalities for children with acute severe paediatric asthma exhibit great variation in the type, number and timing of outcome measures used. There are no patient or family-specific outcomes reported. There is a need to develop international consensus.Trial registration numberCRD42017055331.