Objective: To obtain priority consensus for outcome measures of oral corticosteroid treatment of preschool wheeze that represent stakeholder groups.

Design: (1) A systematic review to identify a set of outcome measures; (2) an international survey for healthcare professionals (HCPs) and a nominal group meeting with parents; (3) a final consensus nominal group meeting with key HCPs (trial investigators and paediatric emergency medicine clinicians) and the same parent group.

Main outcome measures: Consensus priority of treatment outcome measures, outcome minimal clinically important differences (MCIDs) and level of concerns about adverse effects.

Results: Through an iterative process engaging HCPs and parents, the final consensus on a primary outcome was Wheezing Severity Score (WSS). Secondary outcomes prioritised as a revisit to general practice/emergency department, rehospitalisation, length of hospital stay (LOS), time back to normal, doses of short-acting beta-agonists and additional steroid course. Compared with placebo, clinicians considered the median MCID change in WSS at 4 and 12 hours as 40% (IQR 29-51%) and 50% (37-63%) and 5 hours (4-6 hours) for LOS, and 2 days (2-3 days) for a time back to normal. Parents identified MCIDs which were frequently longer than physiologically observed impacts in trials. Concerns about multiple steroid doses were most prevalent.

Conclusions: Stakeholders prioritised change in WSS as the most favourable outcome measure. Our study demonstrated the potential of parent/patient engagement in co-creating patient research outcomes. Incorporating this result in the design of future clinical research will provide a more holistic assessment of the impact of treatment while ensuring relevant primary research outcomes.