McCracken RK, Narayan S, Maclure M, Cooper I, Cui Z, Cullen W, Dormuth C, Hamilton MA, Nolan S, Singer J, Socías ME, Wong S, Klimas J Evaluation of audit and feedback to family physicians on prescribing of opioid analgesics to opioid-naïve patients: a pragmatic randomized delay trial Contemp Clin Trials PubMed