Thirty studies were included in the review (5,737 participants, range 14 to 2,081). There were 10 randomised controlled trials (RCTs), 19 controlled clinical trials and one observational study with no control group. Five studies were rated as strong, 12 as moderate and 13 weak. Main weaknesses related to data collection, reporting of confounders and group comparisons.
A significant effect of drug reminder packaging was reported in 17 studies and related to at least one of the measured adherence outcomes. Twelve studies reported significant adherence improvement when drug reminder packaging was part of a multiple intervention strategy. Six of 10 studies found significantly improved clinical outcomes with multiple adherence-enhancing strategies in the intervention group. Nine studies reported a significant effect when drug reminder packaging was a single intervention but effects were less pronounced than with multiple interventions.
Further results on humanistic outcomes, safety issues and economic outcomes were reported.