Background: The goal for laypersons after training in basic life support (BLS) is to act effectively in an out-of-hospital cardiac arrest situation. However, it is still unclear whether BLS training targeting laypersons at workplaces is optimal or whether other effective learning activities are possible.

Aim: The primary aim was to evaluate whether there were other modes of BLS training that improved learning outcome as compared with a control group, i.e. standard BLS training, six months after training, and secondarily directly after training.

Methods: In this multi-arm trial, lay participants (n = 2623) from workplaces were cluster randomised into 16 different BLS interventions, of which one, instructor-led and film-based BLS training, was classified as control and standard, with which the other 15 were compared. The learning outcome was the total score for practical skills in BLS calculated using the modified Cardiff Test.

Results: Four different training modes showed a significantly higher total score compared with standard (mean difference 2.3–2.9). The highest score was for the BLS intervention including a preparatory web-based education, instructor-led training, film-based instructions, reflective questions and a chest compression feedback device (95% CI for difference 0.9–5.0), 6 months after training.

Conclusion: BLS training adding several different combinations of a preparatory web-based education, reflective questions and chest compression feedback to instructor-led training and film-based instructions obtained higher modified Cardiff Test total scores 6 months after training compared with standard BLS training alone. The differences were small in magnitude and the clinical relevance of our findings needs to be further explored.

Trial Registration: ClinicalTrials.gov Identifier: NCT03618888. Registered August 07, 2018—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03618888 © 2020, The Author(s).