Objective To document the legal guardian-related barriers to consent procurement, and their stated reasons for non-participation in a paediatric critical care research study.

Study design A multicentre, prospective, cohort study.

Participants Legal guardians of children who participated in a multicentre study on adrenal insufficiency in paediatric critical illness. Data were collected on all consent encounters in the main study.

Methods Screening data, reasons for consent not being obtained, paediatric risk of mortality (illness severity) scores and age were collected on all 1707 patients eligible for participation in the Adrenal Insufficiency Study.

Results The main barriers to approaching legal guardians for consent were lack of availability of the legal guardians (321/1707) and language barriers (84/1707). Legal guardians of 917 patients were approached with an overall consent rate of 42% (range 14–56% across the seven sites). 81% of the 528 legal guardians who declined consent provided an unsolicited reason for refusal. The three most commonly stated reasons were: being overwhelmed (117/429), not wanting anything else done to their child (63/429) and not wanting an additional medication (53/429). In addition, 14.2% cited research-related concerns as the reason for their non-participation.

Conclusions Barriers to consent procurement in a non-therapeutic paediatric critical care study appear to occur at many levels with lack of availability of legal guardians, and legal guardians feeling overwhelmed, being the most commonly recorded reasons. Further research into the impact of these findings on the validity and generalisability of the results of such studies is necessary prior to the development and study of future consent models.