Consent models in Canadian critical care randomized controlled trials: a scoping review

Purpose: Our primary objective was to describe consent models used in Canadian-led adult and pediatric intensive care unit (ICU/PICU) randomized controlled trials (RCTs). Our secondary objectives were to determine the consent rate of ICU/PICU RCTs that did and did not use an alternate consent model to describe consent procedures.

Source: Using scoping review methodology, we searched MEDLINE, Embase, and CENTRAL databases (from 1998 to June 2019) for trials published in English or French. We included Canadian-led RCTs that reported on the effects of an intervention on ICU/PICU patients or their families. Two independent reviewers assessed eligibility, abstracted data, and achieved consensus.

Principal findings: We identified 48 RCTs of 17,558 patients. Included RCTs had ethics approval to use prior informed consent (43/48; 90%), deferred consent (13/48; 27%), waived consent (5/48; 10%), and verbal consent (1/48; 2%) models. Fifteen RCTs (15/48; 31%) had ethics approval to use more than one consent model. Twice as many trials used alternate consent between 2010 and 2019 (13/19) than between 2000 and 2009 (6/19). The consent rate for RCTs using only prior informed consent ranged from 54 to 91% (ICU) and 43 to 94% (PICU) and from 78 to 100% (ICU) and 74 to 87% (PICU) in trials using an alternate/hybrid consent model.

Conclusion: Alternate consent models were used in the minority of Canadian-led ICU/PICU RCTs but have been used more frequently over the last decade. This suggests that Canadian ethics boards and research communities are becoming more accepting of alternate consent models in ICU/PICU trials.