Methods to improve patients’ adherence to medicines are generally unproven and there is an urgent need to develop more effective approaches, say the authors of a Cochrane review
Although they identified 182 trials testing interventions to enhance drug adherence, effects were inconsistent and most trials were poor quality.
“The studies varied so much in terms of their design and their results that it would have been misleading to try to come up with general conclusions,” says lead researcher, Robby Nieuwlaat from McMaster University, Hamilton, Canada. “It is uncertain how adherence to medication can be consistently improved. We need to see larger and higher quality trials, which better take into account individual patient’s problems.”
Patients may take only some of their prescribed doses; many stop taking medication altogether and others fail to follow instructions.
Nieuwlaat’s team undertook a systematic review of interventions to improve adherence; just 17 of the 182 randomised controlled trials identified were considered high quality. These generally involved complex interventions, such as tailored ongoing support from pharmacists.
Of the 17 high-quality trials, five found that the intervention led to improvements in both medicines adherence and health outcomes; no common intervention characteristics were apparent, say the authors. Even the most effective interventions had only a modest impact on adherence and clinical outcomes.
“We need more advanced methods for researching ways to improve medicines adherence, including better interventions, better ways of measuring adherence, and studies that include sufficient patients to draw conclusions on clinically important effects,” the researchers conclude.
 Nieuwlaat R, Wilczynski N, Navarro T et al. Interventions for enhancing medication adherence. Cochrane Database of Systematic Reviews 2014;11: CD000011. doi:10.1002/14651858.CD000011.pub3 (accessed on 20 November 2014).