Randomisation
Hospital sites were the unit of randomisation in this trial. Cluster randomisation was necessary to avoid the risk of clinical error from the concurrent reporting of different troponin thresholds and assays. During standard care, all sites initially reported cardiac troponin levels measured using the contemporary cardiac troponin assay, along with corresponding diagnostic thresholds, for at least six months. During the randomisation period, sites were randomly allocated to either early or late implementation of the high sensitivity cardiac troponin assay with sex specific 99th centile thresholds.