Prescription drug monitoring programs evaluation: A systematic review of reviews

•PDMPs are increasingly used globally to mitigate harms from high-risk medicines.•Inconsistent methods and outcome measures were used to evaluate PDMPs.•Evidence that PDMPs improve patient outcomes is low quality and conflicting.•Time and technology integration challenges were most frequently reported barriers to PDMP use.•Mandatory use was viewed negatively by users, but was a facilitator to PDMP use and implementation.