Understanding the applicability of results from primary care trials: lessons learned from applying PRECIS-2

PRECIS-2 can facilitate information exchange within trial teams. To apply PRECIS-2 successfully, we recommend a discussion between those with detailed understanding of what usual care is for the intervention, the trial's design including operational and technical aspects, and the PRECIS-2 domains. For some cluster-randomized trials, greater insight may be gained by plotting two PRECIS-2 wheels, one at the individual participant level and another at the cluster level.